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Organoammonium diphosphopentamolybdates(VI): influence of organic cations and anion protonation on crystal packing and geometrical features of polyanion
Inorganica Chimica Acta 255 (1997) 35–45
Organoammonium diphosphopentamolybdates(VI): influence of organic cations and anion protonation on crystal packing and geometrical features of polyanion Ana Aranzabe a, Ana S.J. We´ry a, Susana Martı´n a, Juan M. Gutie´rrez-Zorrilla a,U, Antonio Luque a, Martı´n Martı´nez-Ripoll b, Pascual Roma´n a,U a
Departamento de Quı´mica Inorga´nica, Universidad del Paı´s Vasco, Apartado 644, 48080 Bilbao, Spain b Departamento de Cristalografı´a, Instituto Rocasolano, CSIC, Serrano 119, 28006 Madrid, Spain
Received 7 February 1996; revised 12 April 1996
Abstract
Four organoammonium diphosphopentamolybdate(VI) with the formulae (C5H7N2)6[P2Mo5O23]P5H2O (1), (C2H10N2)3[P2Mo5O23]P6H2O (2), Al(C4H15N3)4[HP2Mo5O23]2ClP10H2O (3) and (C4H12N)4[H2P2Mo5O23]P5H2O (4) have been synthesized. The crystal structures have been determined by means of single crystal X-ray diffraction data. The geometrical characteristics of the [HnP2Mo5O23](6yn)y heteropolyanions have been compared with those described in the literature for other salts. Several relationships between the protonated state and topological changes in the heteropolyanions have been found. The crystal structure in compound 1 is stabilized by electrostatic forces, an extensive network of hydrogen contacts involving anions, cations and water moleculesand p–p interactions among 4-aminopyridinium cations. The anions of compound 2 are arranged in layers perpendicular to the [1# 10] direction. The interactions between anions are established through hydrogen contacts which involve water molecules and ethylenediammonium cations. The monohydrogendiphosphopentamolybdate(VI) anions in the crystal structure of compound 3 are joined along the [010] direction by means of strong O–H∆O interactions (d(O∆O)s2.529(10) A˚) which lead to a polymeric structure of [HP2Mo5O23]5y polyanions. Likewise, a similar anion polymeric arrangement is found in compound 4 in which the diprotonated polyanions are held together by means of two strong hydrogen bonds (d(O∆O)s2.591(6) and 2.596(6) A˚). Keywords:
Phosphopolyoxometallate complexes; Organoammonium salt complexes; Molybdenum complexes; Crystal packing; Crystal structures
1. Introduction
The chemistry of molybdenum(VI), tungsten(VI) and vanadium(V) in aqueous solution is dominated by the formation of iso- and heteropolyoxometalates. The structures of many salts of heteropolyacids have been determined. The general formula for such compounds may be written as MmHnYyXxOzPpH2O, where M is a cation, X is a non-metal (usually P, Si, B, As or S) and Y is a transition metal (usually Mo, W or V). It was long believed that the ratio x:y was confined to the range 9Fx:yF12 due to the earliest structure determinations [1,2]. In 1971, Petterson found indications for the existence of diphosphopentamolybdate anions, x:ys2.5, in a careful study of aqueous heteropolyanion systems [3]. Later structures such as Na6[P2Mo5O23]P13H2O, Na4[H2P2Mo5O23]P10H2O and (NH4)5[HP2Mo5O23]P U
Corresponding authors.
3H2O were determined [4–6], providing evidence for this. Hori et al. determined the structure of Na[N(CH3)4]3[S2Mo5O23]P4H2O and published a review of the structures of heteropolyacids salts for which the ratio x:y is 2.5 [7]. A polymeric nickel complex with formula (NH4)8Ni[(HP2Mo5O23)2]P12H2O has been described [8]. Recently, a novel conjunction of hetero(macro)cycles and a diphosphopentamolybdate cage has been achieved by the synthesis of the first examples of polyoxomolybdate cages derivatized with hetero(macro)cycles with general formula [(ZP)2Mo5O21]2y [9]. In the last years, there is much current interest in the way molecules and ions are organized in the solid state to form novel materials with improved electrical, optical, magnetic or catalytic properties. In this respect, although there have been theoretical studies on packing interactions in simple organic systems, up to now, very few systematic reports have been published analyzing correlations between the character-
0020-1693/97/$17.00 q 1997 Elsevier Science S.A. All rights reserved PII S0020-1693(96)05201-2
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istic of the individual components (ions or neutral molecules) and the way in which a crystalline inorganiccompound is constructed and organized. This research would be of particular importance in the field of polyoxometalate chemistry, since this kind of compound is used as a catalyst and the features of organic cations play an important role not only in the crystal packing determination but also in the catalytic properties such as particle size, porosity and thermal stability [10]. In this context, during our studies on the chemistry of organic salts of iso- and heteropolyoxometalates, we have chemically and structurally characterized four salts of phosphopolyoxometalates with an x:y ratios2.5: the hexakis(4-aminopyridinium)diphosphopentamolybdate(VI)pentahydrate (1), tris(ethylenediammonium) diphosphopentamolybdate(VI) hexahydrate (2), aluminium tetrakis(3-aza1,5-pentamethylenediammonium) bis[hydrogendiphosphopentamolybdate(VI)] chloride decahydrate (3) and tetrakis(t-butylammonium) dihydrogendiphosphopentamolybdate(VI) pentahydrate (4). The choice of the organoamine bases was determined by the presence of amino groups capable of establishing strong hydrogen bonds which involve the oxygen atoms as acceptors and stabilize the crystal structure of this kind of compound. Second, it is well known that cation features, such as length, size and number of amino groups, play an important role in the crystal packing of polyoxometalate salts. The aim of our work is to study the influence of the cation characteristic and the protonation degree of the polyanion on the structural unit interactions and — as a consequence — on the crystal organization in these phosphomolybdate species with a 2.5 x:y ratio. 2. Results and discussion 2.1. Syntheses and spectroscopic characterization
Isolation of polyanions from solution can be achieved by addition of alkylamines or aromatic amines as counterions
[11–15] that provide groups which may participate in an extensive network of hydrogen bonding with either oxygen atoms from the polyanions or from water molecules playing an important role in the photochemical properties [16–18] of this kind of compound. In the present work we have employed 4-aminopyridine, ethylenediamine, diethylenetriamine and t-butylamine organic bases in order to study the differences present in the crystal structure due to cation– cation and cation–anion interactions. IR spectroscopy is a good method for identifying the type of polyanion and the presence of protonated organic cations. As expected on the basis of the literature the bands corresponding to the heteropolyanions are detectable in the 1300–400 cmy1 range (Table 1) and the presence of well differentiated Mo–O and P–O linkages in the heteropolyanion structure indicates the possibility of a great number of internal vibrations [19]. 2.2. Structures of compounds 1–4
The asymmetrical units of the compounds contain: six 4-aminopyridinium cations, five water molecules and one diphosphopentamolybdate(VI) anion for compound 1; three ethylenediammonium cations, six water molecules and one diphosphopentamolybdate(VI) anion for compound 2; one aluminium, on a two-fold crystallographic axis, two 3-aza1,5-pentamethylenediammonium cations, one chloride anion, 50% population, five water molecules and one hydrogendiphosphopentamolybdate(VI) anion for compound 3; six t-butylammonium cations, five water molecules and one dihydrogendiphosphopentamolybdate(VI) anion for compound 4. The diphosphopentamolybdate anion, [HnP2Mo5O23](6yn)y, is built up of five MoO6 octahedra and two PO4 tetrahedra. The octahedra form a pentagonal ring by sharing four edges and one corner. The PO4 tetrahedra are attached each one to one side of the ring by three oxygen atoms (Fig. 1). Mo–
Table 1 Analytical and spectroscopical data of compounds 1–4 Compound
Analysis (%) C
(C5H7N2)6[P2Mo5O23]P5H2O (1) (C2H10N2)3[P2Mo5O23]P6H2O (2) Al(C4H15N3)4[HP2Mo5O23]2P10H2O (3) (C4H12N)4[H2P2Mo5O23]P5H2O (4) a
H
IR data (cmy1) N
22.7 3.1 10.6 (22.94) (3.34) (10.58) 5.95 3.5 (5.99) (3.50) 7.6 3.5 (7.73) (3.33) 14.9 4.55 (14.80) (4.66)
6.6 (6.98)
d(P–OH)
n (P–Ot)
n (P–Ob)
n (Mo–Ot)
n (Mo–Ob)
Breathing a
1280w 1200m 1090vs 1100s 1085s
1035vs 995s
945m(sh)
890vs 830s(sh)
695vs 675vs
1030s 1005m
975w 915vs
685s(br)
1045m 995m 1065s 1005s
975vs
895sh 870sh 830w 895vs
930vs
900vs
6.4 1275w 1100s (6.76) 4.1 1295w 1100s (4.32) 1210w(br)
715vs(br) 690vs(br) 700vs(br)
Breathing of polyanion.
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Table 2 Mo∆Mo, Mo∆P and P∆P distances (A˚) and Mo–O and P–O bond lengths (A˚) for compounds 1–4
Fig. 1. ORTEP view (thermal ellipsoids at the 50% probability level) of the [HnP2Mo5O23](6yn)y polyanion with atom labelling. For compound 3, the O22 atom is protonated and for compound 4, both the O22 and O23 atoms are protonated.
Mo, Mo–P distances and Mo–O and P–O bond lengths are given in Table 2. Each octahedra has four bridge oxygen atoms and two terminal oxygen atoms. There are two types of Mo–Mo distances: (a) those between octahedra sharing edges (3.319–3.402 A˚); (b) between octahedra sharing corners which are significantly longer (3.671–3.677 A˚). Mo–P distances are in the range 3.311–3.641 A˚. P–P distances are 3.802, 3.793, 3.781 and 3.756 A˚ respectively, for compounds 1–4. The Mo–O bond lengths can be classified into three groups: (i) short, Mo–Ot, 1.692–1.728 A˚; (ii) medium, Mo–Ob, oxygen atoms being shared by two molybdenum atoms, 1.891– 1.958 A˚; (iii) long, Mo–Ob, oxygen atoms being shared by phosphorus and molybdenum atoms, 2.170–2.468 A˚. Each molybdenum atom has two short distances with terminal oxygen atoms, two medium distances and two long ones. The tetrahedral coordination around phosphorus is almost regular, with P–O bond distances ranging between 1.504 and 1.572 A˚. In the non-protonated polyanion the P–O bond distance to the unshared oxygen atom (Ot) is shorter than those involving the oxygen atoms shared by the molybdenum atoms. In compounds 3 and 4 a lengthening of the P–Ot bond distance can be observed for the protonated oxygen. This is in accordance with crystal structures previously reported. Although the polyanions for all four compounds show a similar geometry, the degree of protonation leads to distinguishable features. Polyanions of compounds 1–4 have been compared with other organic and inorganic diphosphopentamolybdate salts previously published (Table 3). The molybdenum atoms of the pentagonal ring are nearly on the same plane and no significant deviations are observed as a consequence of the protonation degree. However, the influence of the protonation is clearly visible in the P–P distances. The higher the protonated state is, the shorter the P–P distance gets. This fact is clearly observable in the sodium salts for which the P–P distances range from 3.824 to 3.707 A˚ in unprotonated and diprotonated anions, respectively. Attachment of a hydrogen atom to one of the terminal oxygen atoms
Mo1–Mo2 Mo2–Mo3 Mo3–Mo4 Mo4–Mo5 Mo5–Mo1 P1–Mo1 P1–Mo2 P1–Mo3 P1–Mo4 P1–Mo5 P2–Mo1 P2–Mo2 P2–Mo3 P2–Mo4 P2–Mo5 P1–P2 Mo1–O1 Mo1–O6 Mo1–O11 Mo1–O15 Mo1–O18 Mo1–O21 Mo2–O2 Mo2–O7 Mo2–O11 Mo2–O12 Mo2–O18 Mo2–O19 Mo3–O3 Mo3–O8 Mo3–O12 Mo3–O13 Mo3–O16 Mo3–O19 Mo4–O4 Mo4–O9 Mo4–O13 Mo4–O14 Mo4–O17 Mo4–O20 Mo5–O5 Mo5–O10 Mo5–O14 Mo5–O15 Mo5–O20 Mo5–O21 P1–O17 P1–O19 P1–O21 P1–O22 P2–O16 P2–O18 P2–O20 P2–O23
1
2
3
4
3.384(1) 3.378(1) 3.671(1) 3.366(1) 3.369(1) 3.496(2) 3.379(2) 3.623(1) 3.319(2) 3.534(2) 3.493(2) 3.569(2) 3.311(2) 3.611(1) 3.423(2) 3.802(2) 1.719(5) 1.715(5) 1.900(5) 1.911(4) 2.329(4) 2.331(4) 1.705(6) 1.718(5) 1.933(4) 1.943(4) 2.429(5) 2.173(4) 1.704(5) 1.710(5) 1.956(4) 1.933(4) 2.174(5) 2.349(4) 1.729(5) 1.723(6) 1.908(4) 1.927(4) 2.226(5) 2.345(4) 1.714(5) 1.711(5) 1.945(4) 1.931(4) 2.192(4) 2.372(4) 1.517(4) 1.563(4) 1.569(4) 1.522(5) 1.537(4) 1.556(4) 1.570(5) 1.512(5)
3.3500(6) 3.3197(6) 3.6656(6) 3.3782(6) 3.3813(5) 3.438(1) 3.446(1) 3.601(1) 3.322(1) 3.547(1) 3.498(1) 3.517(1) 3.304(1) 3.585(1) 3.391(1) 3.793(2) 1.714(3) 1.709(3) 1.901(3) 1.924(3) 2.355(3) 2.284(2) 1.726(3) 1.706(3) 1.957(3) 1.901(3) 2.294(3) 2.221(2) 1.728(3) 1.715(3) 1.922(3) 1.917(3) 2.213(2) 2.340(3) 1.717(3) 1.707(3) 1.909(3) 1.951(3) 2.205(3) 2.339(2) 1.727(3) 1.701(3) 1.950(2) 1.932(3) 2.170(3) 2.383(3) 1.524(3) 1.557(2) 1.557(3) 1.521(3) 1.517(3) 1.568(3) 1.561(3) 1.511(3)
3.402(1) 3.344(1) 3.676(6) 3.379(1) 3.387(1) 3.455(3) 3.399(3) 3.546(3) 3.300(3) 3.572(3) 3.482(3) 3.588(3) 3.320(3) 3.641(3) 3.435(3) 3.781(3) 1.696(8) 1.716(8) 1.902(7) 1.917(7) 2.363(7) 2.312(7) 1.702(7) 1.713(8) 1.937(7) 1.933(7) 2.468(6) 2.223(6) 1.710(7) 1.721(7) 1.910(7) 1.897(6) 2.298(7) 2.271(7) 1.715(7) 1.692(8) 1.921(6) 1.913(7) 2.275(7) 2.418(7) 1.700(7) 1.709(8) 1.932(7) 1.935(7) 2.233(7) 2.387(6) 1.513(8) 1.545(7) 1.552(7) 1.526(7) 1.504(7) 1.521(7) 1.518(7) 1.564(7)
3.384(1) 3.383(1) 3.677(1) 3.348(1) 3.393(1) 3.487(2) 3.424(2) 3.616(2) 3.343(2) 3.517(2) 3.441(2) 3.515(2) 3.341(2) 3.592(2) 3.414(2) 3.756(2) 1.704(4) 1.696(6) 1.921(5) 1.910(5) 2.310(3) 2.347(4) 1.694(6) 1.701(6) 1.925(4) 1.933(4) 2.367(4) 2.212(4) 1.704(5) 1.706(4) 1.921(5) 1.891(4) 2.335(4) 2.388(3) 1.712(4) 1.700(5) 1.899(4) 1.904(3) 2.348(4) 2.337(4) 1.702(4) 1.696(6) 1.926(4) 1.948(4) 2.224(3) 2.357(4) 1.512(4) 1.538(4) 1.536(4) 1.557(5) 1.512(3) 1.529(4) 1.535(4) 1.562(5)
implies an elongation of the P–Ot distance and a shortening of the remaining P–O bond distances. Although, the crystal packing for all four compounds 1–4 shows some common basic features, the most notable being
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Table 3 Distance from the respective ring plane of molybdenum and phosphorus atoms (A˚) and the orientation of the P–P vectors to the ring (8) Compound
Mo1
Mo2
(C5H7N2)6[P2Mo5O23]P5H2O (1) (C2H10N2)3[P2Mo5O23]P6H2O (2) Na6[P2Mo5O23]P14H2O Na6[P2Mo5O23]P13H2O Al(C4H15N3)4[HP2Mo5O23]2ClP10H2O (3) Na5[HP2Mo5O23]P11H2O (NH4)5[HP2Mo5O23]P3H2O (NH4)8Ni[HP2Mo5O23]2P12H2O (C4H12N)4[H2P2Mo5O23]P5H2O (4) Na4[H2P2Mo5O23]P10H2O [C(NH2)3]4[H2P2Mo5O23]PH2O
0.025 0.045 0.010 0.000 y0.008 0.018 0.024 y0.057 0.016 y0.002 0.056
y0.189
0.115 0.200 0.153 y0.159 0.120 0.126 0.197 y0.151 0.165 y0.180
Mo3 0.264
y0.213 y0.315 y0.232
0.249
y0.196 y0.210 y0.245
0.214
y0.248
0.221
the extensive hydrogen bonding network, several significant differences in each crystal organization can be noticed. 2.2.1. Crystal packing in compound 1
The diphosphopentamolybdate anions are located in two
z levels, zs1/4 and zs3/4, parallel to the [100] direction
(Fig. 2). Anions, organic cations and water molecules are joined by a three-dimensional network of hydrogen bonds of types: N–H∆O (2.653–3.228 A˚), N–H∆Ow (2.818–3.420 A˚), Ow–Hw∆O (2.824–3.115 A˚) and Ow–Hw∆Ow (2.765–2.997 A˚). It is interesting to note the distribution of aromatic cations in the unit cell leading to a great number of p–p interactions [23]. The presence of this type of interaction has been evaluated [24] and the results are shown in Table 4. Three face-to-face (P) interactions and two edgeon (T) ones have been found. The face-to-face stacked cations are offset one from another and show a staggered orientation, presumably to minimize electrostatic repulsions
Mo4 y0.250
0.238 0.320 0.232 y0.251 0.207 0.225 0.207 y0.206 0.248 y0.186
Mo5 0.150
y0.184 y0.216 y0.153
0.169
y0.149 y0.166 y0.103
0.127
y0.163
0.089
P1 y1.887
1.907 y1.890 y1.918 y1.858 y1.873 1.895 1.870 y1.885 y1.844 y1.869
P2 1.904
y1.886
1.885 1.904 1.930 1.851 y1.861 y1.899 1.859 1.862 1.909
8
P∆P
Ref.
89.23 88.97 89.45 88.25 89.63 88.15 89.91 89.18 89.06 88.95 89.74
3.791 3.793 3.776 3.824 3.781 3.726 3.756 3.770 3.744 3.707 3.778
this work this work [20] [4] this work [21] [6] [8] this work [5] [22]
and steric hindrances between the ammonium and amine groups. Although face-to-face stacking geometry is disfavored by p–p repulsion, the presence of a positively charged atom, the nitrogen atom of the aromatic ring, leads to these three interactions. It is important to notice the strong interaction between cations Xs6, with a clear overlapping of the aromatic rings. The p–p interactions in the edge-ongeometry take place through the carbon atoms, CX2 and CX3 of the vertical T-group. 2.2.2. Crystal packing in compound 2
The diphosphopentamolybdate anions are arranged in layers perpendicular to the [1# 01] direction (Fig. 3). There is no direct interaction between polyanions belonging to different layers, even though the shortest O∆O distance is 3.365 A˚ between two terminal oxygens O23. The ethylenediammonium cations, with a gauche conformation, and water molecules are located between layers and participate in the
Fig. 2. View along the [010] direction of compound 1.
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Table 4
p-p Interactions in compound 1
Cations
DC
ANG
DZ
DXY
DS
ANGS
RON
Type
1-2 1-3 3-1 5-3 6-6
5.05 4.20 4.20 5.43 3.48
74.3 4.6 4.6 80.0 0.0
4.73 3.60 3.50 4.89 3.48
1.79 2.16 2.32 2.36 0.12
3.76 3.60 3.58 3.69 4.13
103.4 91.6 89.2 134.4 57.5
2.1 16.1 16.1 13.9 0.0
T P P T P
DC: distance between the centroids of the aromatic groups i and j. ANG: angle between the least-squares planes of the two centroids. DZ: distance between the centroid of the i group and the least-squares plane of j. DXY: distance between the centroids of i and j projected onto the least-squares plane of i. DS: distance from the centroid of i to the nearest hydrogen atom of the j group. ANGS: (centroid of i-nearest hydrogen atom of the j group-centroid of j) angle. RON: (ipso carbene of i-centroid of i-centroid of j-nearest hydrogen atom of j) torsion angle.
Fig. 3. Packing in compound 2.
formation of an extensive network of hydrogen bonds of types N–H∆O (2.722–3.151 A˚), N–H∆Ow (2.783–3.165 A˚), Ow–Hw∆O (2.740–3.002 A˚) and Ow–Hw∆Ow (2.713– 2.785 A˚). 2.2.3. Crystal packing in compound 3 The crystal structure of 3 projected onto the (001) plane
is shown in Fig. 4. The hydrogendiphosphopentamolybdate anions are located in two x levels, xs0 and xs1/2. The pentagonal molybdate framework of the anions is located parallel to the (010) plane with the P–P vectors parallel to the [010] direction. The formation of strong hydrogen bonding (d(O∆O)s2.529 A˚) [25] between the protonated terminal oxygen atom O23 and the non-protonated oxygen atom O22 of the adjacent polyanion through the hydrogen atom H1 favors the polymeric disposition of the [HP2Mo5O23]5y polyanions along the b axis. The organic cations occupy the space among the polyanions. One of the 3-aza-1,5-diethylenediammonium cations (Xs1), with a trans configuration, is situated along the [001] direction. The other 3-aza-1,5-diethylenetriammonium cation (Xs2), with gauche–trans–trans–gauche
configuration, is located surrounding two adjacent diphosphopentamolybdate(VI) anions and joining them together by hydrogen bonds that involve the three N atoms. Cations, anions and water molecules are positioned so as to be able to join themselves via hydrogen bonding, N–H∆O (2.727– 3.182 A˚), N–H∆Ow (2.651–2.919 A˚), O–H∆O (2.529 A˚), Ow–Hw∆O (2.728–3.359 A˚), Ow–Hw∆Ow (2.765 A˚), N–H∆Cl (3.071 A˚) and Ow–H∆Cl (3.002 A˚). 2.2.4. Crystal packing in compound 4 The crystal structure of 4 is shown
in Fig. 5. Each [H2P2Mo5O23]4y anion is joined with the two adjacent polyanions by means of strong hydrogen contacts of the type O–H∆O (O22∆O17s2.591 and O23∆O16s2.596 A˚) [25], forming chains parallel to the [001] direction. This catenary arrangement is reinforced with other hydrogen bonds that involve the water molecules and the cations Xs1 (N11) and Xs3 (N31). Anions placed in different chains are joined through the water molecules O24w and O25w. The hydrophobic groups of the t-butylammonium cations are directed towards the regions ys0 and xs1/2. The different hydrogen bonds within the structure can be classified into
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the total organic cation pyrolysis and the inorganic residue evolution. For compounds 1, 2 and 4, final residues were identified by their X-ray powder diffraction patterns as a mixture of MoO3 and P2O5 in an approximate 5:1 ratio. However, other peaks are observed in the diffractograms which could not be identified but they may be attributable to phosphomolybdo species. For compound 3, several peaks corresponding to Al2O3 can also be detected. 3. Conclusions
Fig. 4. View along the [001] direction of compound 3. Down: a axis; right: b axis.
The crystallographic study of the diphosphopentamolybdate salts reported here, together with the ones previously published, reveal that the protonated or unprotonated state of the diphosphopentamolybdate anion and the type of counterion have a strong influence on the crystal packing of the diphosphopentamolybdate salts (Table 5). The salts of the unprotonated diphosphopentamolybdate anion present a crystal packing based on polyanion layers whereas monoprotonated and diprotonated anions lead to a catenary arrangement of polyanions through hydrogen bonds, involving the terminal oxygen atoms of the PO4 groups, such as Ot–H∆Ot for monoprotonated or Ot–H∆Op for diprotonated anions. Although this fact is always observed whenever an organic counterion is used, some specific considerations must be pointed out if an inorganic counterion like Naq is present. This cation induces the formation of a catenary arrangement of polyanions through its coordination sphere no matter the protonation state. 4. Experimental 4.1. Materials and methods
Fig. 5. View along the [100] direction of compound 4.
five types: N–H∆O (2.879–3.351 A˚), N–H∆Ow (2.799– 3.340 A˚), O–H∆O (2.591–2.596 A˚), Ow–Hw∆O (2.808– 3.190 A˚) and Ow–Hw∆Ow (2.760–3.050 A˚). Similar hydrophobic zones have been found in the crystal structure of other t-butylammonium polyoxometallates [26]. 2.3. Thermal analysis
The thermal behavior of the compounds was studied under dynamic air atmosphere. All the compounds are quite stable and their thermal degradation starts with the loss of the crystallization water molecules during several overlapped endothermic processes which take place between 50 and 135 8C. The anhydrous compounds are stable up to around 200 8C beyond which the thermal decompositions are followed by
All reagents were purchased from Merck and were used without further purification. C, H and N analyses were performed on a Perkin-Elmer 240 analyzer. The densities were measured by flotation in CHBr3/CCl4. IR spectra were recorded in the 4000–400 cmy1 range on a Nicolet 740 FTIR spectrometer, and the solid compounds were mixed with fused potassium bromide and pressed into transparent disks. A Setaram TAG 24 S16 thermobalance was used to obtain the differential thermal analysis (DTA) and thermogravimetric analysis (TGA) curves, simultaneously, in an argon– oxygen atmosphere (4:1) with a heating rate of 5 8C miny1. 4.2. Preparation of (C5H7N2)6[P2Mo5O23]P5H2O (1)
Colorless single crystals of 4-aminopyridiniumdiphosphopentamolybdate(VI) pentahydrate were obtained from a solution prepared by adding 4-aminopyridine (0.35 g, 3.5 mmol) to a solution of Na2MoO4P2H2O (2.5 g, 10.3 mmol) and Na2HPO4P2H2O (0.50 g, 3.5 mmol) in water (200 ml),
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Table 5 Packing study of the diphosphopentamolybdate salts Compound
Cation
Packing
L∆L a
(C5H7N2)6[P2Mo5O23]P5H2O (1) (C2H10N2)3[P2Mo5O23]P6H2O (2) Na6[P2Mo5O23]P14H2O
C5H7N2q C2H10N22q Naq
8.3 7.7
Na6[P2Mo5O23]P13H2O
Naq
layers parallel to [001] layers parallel to (1# 10) chains Mo–O∆Na∆O–Mo parallel to [010] layers parallel to (1# 20) chains Mo–O∆Na∆O–Mo in zigzag parallel to [001] layers parallel to (100)
Al(C4H15N3)4[HP2Mo5O23]2ClP10H2O (3) Na5[HP2Mo5O23]P11H2O
C4H15N32q, Al3q Naq
(NH4)5[HP2Mo5O23]P3H2O (NH4)8Ni[HP2Mo5O23]P12H2O
NH4q NH4q, Ni2q
(C4H12N)4[H2P2Mo5O23]P5H2O (4) Na4[H2P2Mo5O23]P10H2O
C4H12Nq Naq
[C(NH2)3]4[H2P2Mo5O23]PH2O
C(NH2)3q
a b
chains P2–Ot–H∆Ot–P1 parallel to [010] chains P2–Ot–H∆Ot–P1 parallel to [001] layers parallel to (100) chains P1–Ot–H∆Ob–P2 parallel to [101] chains P2–Ot–H∆Ob–P2 and P1–Ot–Ni– Ot–P1 parallel to [101] chains P–Ot–H∆Ob–P parallel to [001] chains Mo–O∆Na∆O–Mo in zigzag perpendicular to [001] layers parallel to (100) chains P–Ot–H∆Ob–P parallel to [100]
O∆O b
Ref.
5.5
this work this work [20]
8.2
9.1
7.3
[4] 2.54 2.56
this work [21]
2.57 2.66
[6] [8]
2.53 5.23
this work [5]
2.56
[22]
Distance between adjacent layers of polyanion. Shortest distance between oxygen atoms from adjacent polyanions in the same chain.
Table 6 Crystallographic details for compounds 1–4 Compound Formula weight Crystal system Space group ˚) a (A ˚) b (A ˚) c (A a (8) b (8) g (8) ˚ 3) V (A Do (g cmy3) Dx (g cmy3) Z F(000) m (l Mo Ka) (cmy1)
Diffractometer Crystal size (mm) Radiation (Mo Ka) (A˚) Temperature (K) u Range (8) Range of h; k; l No. unique reflections No. observed reflections No. variables R Rw
1
2
3
4
1570.45 monoclinic P21/n 13.891(4) 18.621(2) 21.345(1) 90 103.96(1) 90 5358(2) 1.96(1) 1.947 4 3120 12.63 CAD4 0.50=0.40=0.30 0.71069 293(1) 2–25 0,16; 0,22; y25,25 9232 6688 (IG3s (I)) 739 0.036 0.041
1204.06 triclinic P1# 10.409(3) 11.683(1) 13.968(1) 100.50(1) 99.55(1) 89.93(1) 1646.3(5) 2.42(1) 2.429 2 1184 20.14 CAD4 0.70=0.45=0.10 0.71069 293(1) 1–30 0,14; y16,16; y19,19 9691 8460 (IG3s (I)) 524 0.033 0.046
2484.60 monoclinic I2/a 20.330(2) 16.754(2) 21.606(3) 90 95.11(3) 90 7330(2) 2.23(1) 2.252 4 4880 18.58 Philips PW1100 0.50=0.10=0.10 0.71069 294(1) 2–22 0,22; 0,18; y22,22 4493 3634 (IG3s (I)) 453 0.050 0.052
1298.31 triclinic P1# 12.511(2) 13.216(2) 14.465(3) 107.36(4) 100.69(3) 96.16(2) 2209.2(9) 1.94(1) 1.950 2 1296 15.06 CAD4 0.15=0.15=0.28 0.71069 293(1) 1–30 0,17; y18,18; y20,20 12855 8239 (IG3s (I)) 488 0.037 0.044
previously mixed with stirring during half an hour at room temperature until dilution. HCl 6.0 M was added to bring the solution to the pH value of 6. Crystals were filtered off, washed with diethyl ether and then carefully dried in air.
4.3. Preparation of (C2H10N2)3[P2Mo5O23]2P6H2O (2)
To an aqueous solution (200 ml) of Na2MoO4P2H2O (4.84 g, 20.0 mmol) and Na2HPO4P2H2O (0.76 g, 4.3
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Table 7 Atomic parameters for compound 1
Table 7 (continued) Atom
Atom
x
y
z
Mo1 Mo2 Mo3 Mo4 Mo5 P1 P2 O1 O2 O3 O4 O5 O6 O7 O8 O9 O10 O11 O12 O13 O14 O15 O16 O17 O18 O19 O20 O21 O22 O23 O24w O25w O26w O27w O28w N11 C12 C13 C14 C15 C16 N17 N21 C22 C23 C24 C25 C26 N27 N31 C32 C33 C34 C35 C36 N37 N41 C42 C43 C44 C45
0.73698(4) 0.55115(4) 0.38293(4) 0.43886(4) 0.67252(4) 0.48838(10) 0.61576(11) 0.77824(33) 0.47927(34) 0.28491(31) 0.33897(33) 0.69971(32) 0.83213(31) 0.62746(36) 0.33450(32) 0.46600(35) 0.73808(35) 0.64084(29) 0.45957(30) 0.37549(29) 0.54313(29) 0.76329(30) 0.52130(28) 0.42476(30) 0.65296(28) 0.47601(28) 0.58701(28) 0.60004(28) 0.45669(30) 0.69490(30) 0.29926(44) 0.97887(41) 0.81674(43) 0.29781(47) 0.23109(57) 0.76480(49) 0.76181(57) 0.67569(51) 0.58795(57) 0.59271(67) 0.67843(63) 0.50266(43) 0.67080(48) 0.62735(68) 0.61362(71) 0.64656(57) 0.69398(78) 0.70340(79) 0.62890(61) y0.10864(48) y0.04362(66) 0.04965(58) 0.09071(54) 0.02202(58) y0.07370(68) 0.18750(43) 0.03016(55) 0.12770(65) 0.16277(53) 0.10214(57) 0.00207(58)
0.24982(3) 0.13546(3) 0.22370(3) 0.41439(3) 0.41688(3) 0.30051(8) 0.27702(8) 0.27161(26) 0.09161(25) 0.20721(26) 0.46647(25) 0.45849(23) 0.19785(25) 0.07027(24) 0.20186(26) 0.44927(27) 0.46501(24) 0.17919(22) 0.13719(22) 0.32723(22) 0.46158(21) 0.33672(22) 0.24819(23) 0.36280(22) 0.22272(21) 0.23880(21) 0.34953(20) 0.32419(21) 0.27481(23) 0.29041(23) 0.38174(31) 0.24390(33) 0.47877(35) 0.41922(36) 0.33628(39) 0.26957(37) 0.33553(43) 0.37509(41) 0.34500(38) 0.27439(45) 0.23914(43) 0.38032(36) 0.40767(34) 0.40442(44) 0.46386(46) 0.53063(41) 0.53215(44) 0.47034(52) 0.59108(42) 0.30154(44) 0.25180(52) 0.26586(44) 0.33109(43) 0.38027(51) 0.36355(55) 0.34368(39) 0.32634(42) 0.32448(49) 0.37033(46) 0.42355(39) 0.42524(50)
0.36898(2) 0.30221(3) 0.18733(2) 0.22164(3) 0.31391(2) 0.34489(7) 0.20728(7) 0.44927(21) 0.34451(23) 0.22080(22) 0.22805(24) 0.38783(21) 0.35582(23) 0.28407(24) 0.10813(21) 0.15327(22) 0.26983(22) 0.37551(19) 0.21732(20) 0.18725(20) 0.28447(19) 0.32861(19) 0.16124(19) 0.31317(19) 0.26341(18) 0.29393(18) 0.23580(18) 0.36352(18) 0.40455(20) 0.17078(20) 0.72326(30) 0.52502(25) 0.70942(34) 0.38880(33) 0.59664(33) 0.88280(32) 0.85853(38) 0.84456(40) 0.85348(37) 0.87949(46) 0.89157(45) 0.83784(40) 0.09129(31) 0.02982(44) y0.00855(36) 0.01879(35) 0.08357(41) 0.11815(38) y0.01717(36) 0.21198(38) 0.19744(54) 0.20709(46) 0.23626(38) 0.25024(48) 0.23912(48) 0.24943(36) y0.00859(33) 0.02430(40) 0.07357(40) 0.08909(35) 0.05354(43) (continued)
C46 N47 N51 C52 C53 C54 C55 C56 N57 N61 C62 C63 C64 C65 C66 N67
x
y
y0.02610(61)
0.13838(50) 0.47719(69) 0.56356(88) 0.62568(60) 0.59399(59) 0.49678(76) 0.44544(104) 0.65409(53) 0.87618(77) 0.85600(75) 0.90612(66) 1.00198(71) 1.02339(63) 0.96173(85) 1.05288(75)
0.37634(59) 0.47343(38) 0.44842(56) 0.42473(54) 0.39166(48) 0.38315(42) 0.40386(73) 0.43938(86) 0.35600(42) 0.57505(73) 0.50862(56) 0.46860(54) 0.50321(63) 0.57063(44) 0.60211(78) 0.47247(59)
z
0.00582(45) 0.13466(37) 0.61143(50) 0.64171(48) 0.60947(39) 0.54258(35) 0.51289(54) 0.54843(79) 0.50946(33) 0.50193(41) 0.52359(47) 0.57089(40) 0.60520(44) 0.58452(39) 0.53379(54) 0.64970(45)
mmol), 0.50 ml (7.5 mmol) of ethylenediamine was added dropwise with stirring. The final pH was adjusted to a value of 6 by using HCl (2.0 M). A white precipitate, identified as compound 2 appeared after 3 weeks. Single crystals can be obtained by recrystallization in water. 4.4. Preparation of Al(C4H15N3)4[HP2Mo5O23]2ClP10H2O (3)
This compound was prepared by the same method as for adding the diethylenetriamine (0.40 ml, 3.5 mmol) to a solution of Na2MoO4P2H2O (5.0 g, 20.6 mmol) and Na2HPO4 (0.50 g, 3.5 mmol) in water (200 ml). HCl was added to bring the pH to 3. Crystals of 3 appeared after two weeks. They were filtered off, washed with diethyl ether, and then dried in open air for a few hours. The presence of aluminium in this compound was determined by EDAX and the atomic absorption technique was used in order to find the reactant with aluminium impurities. In the Na2MoO4 compound impurities of aluminium were detected. 1,
4.5. Preparation of (C4H12N)4[H2P2Mo5O23]2P5H2O (4) Method A. Solutions of t-butylammonium molybdate (2.0 g, 6.5 mmol) in 50 ml of water and 2.0 ml of H3PO4 (1:10 dilution) were mixed and HCl (3.0 M) was added to bring the pH;3. After two weeks prismatic crystals were obtained. Method B. To an aqueous solution (10 ml) of Na2MoO4P2H2O (5.0 g, 20.6 mmol) were added 5.5 ml (82 mmol) of H3PO4 (85%). The resulting solution was refluxed with stirring for 2 h. Several drops of Br2 were added to remove the pale-green color of the solution. Then 5.5 g (50 mmol) of t-butylammonium chloride were added. Very nice colorless single crystals of compound 4 appeared overnight. 4.6. Crystallography
Crystal data and experimental detail of the four samples are displayed in Table 6. Lattice constants were determined
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Table 8 Atomic parameters for compound 2
Table 9 Atomic parameters for compound 3
Atom
x
y
z
Mo1 Mo2 Mo3 Mo4 Mo5 P1 P2 O1 O2 O3 O4 O5 O6 O7 O8 O9 O10 O11 O12 O13 O14 O15 O16 O17 O18 O19 O20 O21 O22 O23 O24w O25w O26w O27w O28w O29w N11 C12 C13 N14 N21 C22 C23 N24 N31 C32 C33 N34
0.09534(3) 0.26776(3) 0.42042(3) 0.27569(3) 0.12341(3) 0.08777(7) 0.38945(8) y0.06924(29) 0.19944(27) 0.34794(27) 0.22398(29) y0.04092(30) 0.16198(36) 0.33195(29) 0.58094(26) 0.40325(28) 0.19702(34) 0.10307(24) 0.41929(25) 0.36869(25) 0.14357(24) 0.14362(26) 0.48260(23) 0.11555(23) 0.30823(23) 0.21121(22) 0.29554(23) 0.05914(24) y0.02941(24) 0.45837(27) 0.91723(31) 0.46633(34) 0.86146(38) 0.42261(39) 0.72843(66) 0.23381(122) 0.69649(31) 0.67276(42) 0.61308(44) 0.49084(36) 0.81489(36) 0.68838(41) 0.70364(44) 0.75753(34) 0.22478(38) 0.14561(46) 0.00504(49) y0.05931(37)
0.32922(2) 0.08760(2) 0.03782(2) 0.23230(2) 0.43264(2) 0.12902(7) 0.31450(7) 0.34457(27) y0.04865(23) y0.09845(23) 0.16642(26) 0.45729(29) 0.39254(27) 0.13165(26) 0.01052(25) 0.31969(26) 0.56214(26) 0.16845(22) 0.04298(24) 0.10985(22) 0.34993(22) 0.45074(22) 0.22045(22) 0.13116(22) 0.27211(21) 0.08411(21) 0.32884(22) 0.25455(21) 0.04898(23) 0.42816(22) 0.27485(28) 0.27240(30) 0.05015(36) 0.49104(34) 0.45357(47) 0.53851(99) 0.39145(30) 0.27278(36) 0.27369(39) 0.34077(31) 0.08112(29) 0.11714(43) 0.22385(41) 0.20025(36) 0.15089(36) 0.25598(41) 0.22373(42) 0.16651(34)
y0.07776(2) y0.07156(2) y0.26509(2) y0.42928(2) y0.28445(2) y0.29227(6) y0.16892(6) y0.08268(25) y0.07791(21) y0.31097(21) y0.54991(20) y0.31314(23)
0.04016(22) 0.05028(20) y0.27150(22) y0.43747(23) y0.28561(23) y0.07021(19) y0.12687(19) y0.37773(18) y0.41533(18) y0.14242(18) y0.20015(19) y0.39567(17) y0.09625(18) y0.23256(17) y0.26516(18) y0.24315(18) y0.29777(19) y0.11704(21) 0.45810(24) 0.28878(27) 0.88833(26) 0.38008(32) 0.78842(37) 0.49496(92) y0.00526(25) 0.01463(32) 0.10539(34) 0.10577(29) y0.47766(25) y0.44687(31) y0.36669(34) y0.26734(26) 0.24773(29) 0.23748(41) 0.19875(38) 0.26675(31)
by least-squares refinement of the angular setting of 25 reflections. Intensities were collected with the v–2u scan technique. Crystal stability was monitored by recording two check reflections at intervals of 200 data for compounds 1 and 3 and every 100 reflections for compounds 2 and 4; no significant variations were detected. All data were corrected for Lorentz and polarization effects. An empirical absorption correction was applied [27].
Atom
x
y
z
Mo1 Mo2 Mo3 Mo4 Mo5 P1 P2 Al1 Cl1 O1 O2 O3 O4 O5 O6 O7 O8 O9 O10 O11 O12 O13 O14 O15 O16 O17 O18 O19 O20 O21 O22 O23 O24w O25w O26w O27w O281w O282w N11 C12 C13 N14 C15 C16 N17 N21 C22 C23 N24 C25 C26 N27 H1
0.90844(4) 0.86377(4) 1.00072(4) 1.13991(4) 1.07502(4) 0.99925(13) 0.99980(13) 0.25000(–) 0.70464(32) 0.89661(38) 0.82976(36) 0.99327(34) 1.19810(34) 1.08103(38) 0.85346(40) 0.79984(37) 1.01674(35) 1.18378(37) 1.11809(37) 0.86472(33) 0.91001(33) 1.08600(32) 1.13957(32) 0.98768(32) 1.00581(33) 1.07040(34) 0.93253(32) 0.96685(30) 1.05534(33) 0.99571(31) 0.96238(32) 1.00397(35) 0.68187(42) 0.24340(41) 0.50341(39) 0.28590(41) 0.13779(111) 0.18671(152) 0.09622(46) 0.14415(61) 0.10697(55) 0.15482(47) 0.12320(51) 0.17561(55) 0.14498(47) 0.39678(52) 0.42438(54) 0.49120(53) 0.54129(40) 0.61243(52) 0.65953(54) 0.66957(41) 1.0219(84)
0.86231(5) 0.87689(5) 0.85804(5) 0.88533(5) 0.85338(5) 0.97795(15) 0.75237(14) 0.37994(29) 0.33548(39) 0.93061(47) 0.95983(44) 0.94642(40) 0.95394(44) 0.92146(44) 0.78766(45) 0.81009(46) 0.79119(43) 0.79948(45) 0.77257(46) 0.91440(40) 0.83329(39) 0.87188(39) 0.90146(43) 0.81079(41) 0.74566(39) 0.99132(40) 0.78564(36) 0.92250(38) 0.80407(40) 0.93741(38) 1.05728(38) 0.66741(39) 0.15173(48) 0.49982(56) 0.66317(42) 0.14387(53) 0.24472(139) 0.28578(193) y0.08204(55) y0.05551(84) y0.01504(77) 0.00566(60) 0.05045(73) 0.09183(67) 0.12284(59) 0.17311(58) 0.09722(63) 0.10274(68) 0.12747(51) 0.12759(64) 0.14913(63) 0.08253(55) 0.6278(100)
0.86684(4) 0.71171(4) 0.63791(4) 0.75671(4) 0.89320(4) 0.77300(12) 0.76782(12) 0.00000(–) 0.08337(30) 0.92273(35) 0.67643(35) 0.59835(32) 0.73930(35) 0.95176(32) 0.87956(36) 0.71008(36) 0.58068(31) 0.75674(35) 0.92324(36) 0.79657(31) 0.64501(31) 0.67980(31) 0.84435(30) 0.90108(31) 0.69912(30) 0.76022(33) 0.77986(30) 0.72190(29) 0.79733(30) 0.83719(30) 0.77289(32) 0.79786(31) 0.31830(37) 0.38379(42) 0.04547(34) 0.17530(42) 0.49510(106) 0.50021(143) 0.40046(41) 0.45379(55) 0.50339(53) 0.55704(44) 0.60717(56) 0.64910(51) 0.70455(43) 0.10765(51) 0.08860(50) 0.06406(47) 0.11359(38) 0.09577(46) 0.15177(52) 0.19551(42) 0.7808(78)
The positions of Mo and P atoms were located on a Patterson map for compound 1, by using DIRDIF [28] for compound 2, and SIR88 [29] for compounds 3 and 4. The remaining non-H atoms of the structures and the hydrogen
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Table 10 Atomic parameters for compound 4 Atom
x
y
z
Mo1 Mo2 Mo3 Mo4 Mo5 P1 P2 O1 O2 O3 O4 O5 O6 O7 O8 O9 O10 O11 O12 O13 O14 O15 O16 O17 O18 O19 O20 O21 O22 O23 O24w O25w O26w O27w O28w N11 C12 C13 C14 C15 N21 C22 C23 C24 C25 N31 C32 C33 C34 C35 N41 C42 C43 C44 C45 H1 H2
0.32567(4) 0.22010(5) y0.05544(4) y0.12547(4) 0.11514(4) 0.08277(11) 0.10118(11) 0.39536(38) 0.22896(45) y0.09599(40) y0.23589(34) 0.16315(40) 0.42667(38) 0.31019(43) y0.13255(38) y0.17578(35) 0.09319(42) 0.30771(34) 0.08648(35) y0.12726(31) y0.03426(32) 0.25341(33) 0.01887(30) y0.03410(29) 0.20486(31) 0.08248(31) 0.04458(30) 0.16069(30) 0.12982(34) 0.14151(32) 0.38421(46) 0.63885(57) 0.42145(77) 0.35416(67) 0.95301(82) 0.18726(51) 0.22132(74) 0.22533(130) 0.32740(158) 0.15046(176) 0.69371(45) 0.61483(57) 0.57651(89) 0.67740(95) 0.52097(93) 0.11863(58) 0.11525(63) y0.00111(70) 0.19811(73) 0.14774(85) 0.70771(81) 0.61371(64) 0.51374(89) 0.61571(111) 0.65132(305) 0.0948(71) 0.0938(72)
0.58829(5) 0.32230(4) 0.29171(4) 0.55867(4) 0.73013(4) 0.48546(11) 0.50756(11) 0.65296(43) 0.23301(40) 0.21474(34) 0.55433(37) 0.81527(35) 0.58735(46) 0.29406(44) 0.22351(34) 0.59956(36) 0.81081(37) 0.44476(35) 0.25377(31) 0.41054(30) 0.68816(31) 0.69668(33) 0.40781(29) 0.50581(29) 0.47882(31) 0.38998(29) 0.57844(29) 0.58570(30) 0.45335(34) 0.57232(32) 0.42643(56) 0.42502(61) 0.44220(106) 0.29810(74) 0.23519(109) 0.25615(45) 0.15409(58) 0.15164(127) 0.14376(136) 0.06643(171) 0.23628(44) 0.13050(56) 0.11210(83) 0.04549(76) 0.13971(98) 0.21105(45) 0.09140(53) 0.03738(64) 0.06065(61) 0.06796(78) 0.34864(103) 0.28401(65) 0.25873(168) 0.27760(160) 0.18059(308) 0.4684(71) 0.5807(70)
0.32962(4) 0.22987(4) 0.14097(4) 0.24812(4) 0.33022(4) 0.38033(9) 0.13060(9) 0.44976(35) 0.29290(36) 0.20824(33) 0.30212(33) 0.44896(34) 0.26590(38) 0.15476(36) 0.02386(31) 0.15032(32) 0.25932(37) 0.33667(29) 0.12863(28) 0.18256(28) 0.33807(29) 0.29548(30) 0.06610(26) 0.37853(26) 0.18424(26) 0.28810(27) 0.20480(27) 0.38470(27) 0.47300(28) 0.06550(28) 0.52522(42) 0.98210(62) 0.85642(69) 0.96480(64) 0.41270(63) 0.49977(45) 0.50933(64) 0.60532(120) 0.48349(129) 0.42680(157) 0.86509(42) 0.82760(56) 0.91434(81) 0.78464(96) 0.75360(94) y0.07066(45) y0.11037(49) y0.12129(60) y0.03550(63) y0.20962(61) 0.36897(83) 0.28970(62) 0.31138(81) 0.19070(106) 0.29357(274) 0.5068(65) 0.0240(64)
atoms of the polyanions were found on successive Fourier syntheses. Anisotropic refinements were carried out by fullmatrix least-squares analyses. The hydrogen atoms of the
cations and water molecules were placed in calculated positions and assigned fixed isotropic thermal parameters.Inaddition, the hydrogen atoms belonging to the protonated anions were found in the corresponding electron density difference map and refined in their positions. Final positionalparameters are reported in Tables 7–10. Most calculations were carried out using the XRAY76 system [30] running on a MicroVAX II computer. Acknowledgements
We thank Iberduero, S.A. and UPV/EHU (Grant No. 169.310-EA134/95) for financial support. A.S.J.W. acknowledges financial support from Departamento Educacio´n (Gobierno Vasco) (Grant No. BFI 94.180 EK). References
[1] J.F. Keggin, Nature, 131 (1933) 908. [2] B. Dawson, Acta Crystallogr., 6 (1953) 113. [3] L. Petterson, Acta Chem. Scand., 25 (1971) 1959. [4] R. Strandberg, Acta Chem. Scand., 27 (1973) 1004. [5] B. Hedman, Acta Chem Scand., 27 (1973) 3335. [6] J. Fisher, L. Ricard and P. Toledano, J. Chem. Soc., Dalton Trans., (1974) 941. [7] T. Hori, S. Himeno and O. Tomada, J. Chem. Soc., Dalton Trans., (1992) 275. [8] E.K. Andersen and J. Villadsen, Acta Chem. Scand., 47 (1993) 748. [9] M.P. Lowe, J.C. Lockhart, G.A. Clegg and K.A. Fraser, Angew. Chem., Int. Ed. Engl., 33 (1994) 451; M.P. Lowe, J.C. Lockhart, G.A. Forsyth, W. Clegg and K. A. Fraser, J. Chem. Soc., Dalton Trans., (1995) 145. [10] A. Corma, Chem. Rev., 95 (1995) 559. [11] P. Roma´n, J.M. Gutie´rrez-Zorrilla, M. Martı´nez Ripoll and S. Garcı´aBlanco, Z. Kristallogr., 173 (1985) 283. [12] P. Roma´n, J.M. Gutie´rrez-Zorrilla, A. Luque and M. Martı´nez Ripoll, J. Crystallogr. Spectrosc. Res., 18 (1988) 117. [13] P. Roma´n, J.M. Gutie´rrez-Zorrilla, A. Luque and F.J. Zu´n˜iga, Z. Kristallogr., 190 (1990) 249. [14] P. Roma´n, A. Luque, A. Aranzabe and J.M. Gutie´rrez-Zorrilla, Polyhedron, 11 (1992) 2027. [15] P. Roma´n, A. Aranzabe, A. Luque, J.M. Gutie´rrez-Zorrilla and M. Martı´nez Ripoll, J. Chem. Soc., Dalton Trans., (1995) 2225. [16] T. Yamase, J. Chem. Soc., Dalton Trans., (1987) 1597. [17] T. Yamase and T. Ushami, J. Chem. Soc., Dalton Trans., (1988) 183. [18] H. Naruke and T. Yamase, J. Lumin., 50 (1991) 55. [19] L. Lyhamn, Acta. Chem. Scand., Ser. A, 36 (1982) 595. [20] B. Hedman, Acta Crystallogr., Sect. B, 33 (1977) 3083. [21] B. Hedman and R. Strandberg, Acta Crystallogr., Sect. B, 35 (1979) 278. [22] D.G. Lyxell, R. Strandberg, D. Bostrom and L. Petterson, Acta Chem. Scand., 45 (1991) 681. [23] C.A. Hunter and J.K.M. Sanders, J. Am. Chem. Soc., 112 (1990) 5525. [24] A. Albert and F.H. Cano, CONTACTOS, computer program to study interactions between aromatic rings, Instituto Rocasolano, CSIC, Madrid, 1993. [25] P. Gilli, V. Bertolasi, V. Ferreti and G. Gilli, J. Am. Chem. Soc., 116 (1994) 909. [26] P. Roma´n, A. San Jose´, A. Luque, J.M. Gutie´rrez-Zorrilla and M. Martı´nez Ripoll, Acta Crystallogr., Sect. C, 50 (1994) 1189; P. Roma´n, A. San Jose´, A. Luque and J.M. Gutie´rrez-Zorrilla, Acta Crystallogr., Sect. C, 50 (1994) 1031.
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[27] N. Walker and D. Stuart, Acta Crystallogr., Sect. A, 39 (1983) 158. [28] P.T. Beurkens, H.M. Doesburg, R.O. Gould, T.E.M. Vander Hark, P.A.J. Prock, J.H. Noordik, G. Beurskens and V. Parthasarathi, The DIRDIF Program System, Crystallography Lab., Tournooiveld 6525 ED, Nijmegen, Netherlands, 1982.
45
[29] M.C. Burla, M. Camalli, G. Cascarano, C. Giacovazzo, G. Polidori, R. Spagna and D. Viterbo, J. Appl. Crystallogr., 22 (1989) 389. [30] J.M. Stewart, P.A. Machin, C.W. Dickinson, H.L. Ammon, H. Heck and H.D. Flack, The XRAY 76 System, Tech. Rep. TR-446, Computer Science Center, University of Maryland, 1976.
Journal: ICA (Inorganica Chimica Acta)
Article: 5201
Organoammonium diphosphopentamolybdates(VI): influence of organic cations and anion protonation on crystal packing and geometrical features of polyanion Ana Aranzabe a, Ana S.J. We´ry a, Susana Martı´n a, Juan M. Gutie´rrez-Zorrilla a,U, Antonio Luque a, Martı´n Martı´nez-Ripoll b, Pascual Roma´n a,U a
Departamento de Quı´mica Inorga´nica, Universidad del Paı´s Vasco, Apartado 644, 48080 Bilbao, Spain b Departamento de Cristalografı´a, Instituto Rocasolano, CSIC, Serrano 119, 28006 Madrid, Spain
Received 7 February 1996; revised 12 April 1996
Abstract
Four organoammonium diphosphopentamolybdate(VI) with the formulae (C5H7N2)6[P2Mo5O23]P5H2O (1), (C2H10N2)3[P2Mo5O23]P6H2O (2), Al(C4H15N3)4[HP2Mo5O23]2ClP10H2O (3) and (C4H12N)4[H2P2Mo5O23]P5H2O (4) have been synthesized. The crystal structures have been determined by means of single crystal X-ray diffraction data. The geometrical characteristics of the [HnP2Mo5O23](6yn)y heteropolyanions have been compared with those described in the literature for other salts. Several relationships between the protonated state and topological changes in the heteropolyanions have been found. The crystal structure in compound 1 is stabilized by electrostatic forces, an extensive network of hydrogen contacts involving anions, cations and water moleculesand p–p interactions among 4-aminopyridinium cations. The anions of compound 2 are arranged in layers perpendicular to the [1# 10] direction. The interactions between anions are established through hydrogen contacts which involve water molecules and ethylenediammonium cations. The monohydrogendiphosphopentamolybdate(VI) anions in the crystal structure of compound 3 are joined along the [010] direction by means of strong O–H∆O interactions (d(O∆O)s2.529(10) A˚) which lead to a polymeric structure of [HP2Mo5O23]5y polyanions. Likewise, a similar anion polymeric arrangement is found in compound 4 in which the diprotonated polyanions are held together by means of two strong hydrogen bonds (d(O∆O)s2.591(6) and 2.596(6) A˚). Keywords:
Phosphopolyoxometallate complexes; Organoammonium salt complexes; Molybdenum complexes; Crystal packing; Crystal structures
1. Introduction
The chemistry of molybdenum(VI), tungsten(VI) and vanadium(V) in aqueous solution is dominated by the formation of iso- and heteropolyoxometalates. The structures of many salts of heteropolyacids have been determined. The general formula for such compounds may be written as MmHnYyXxOzPpH2O, where M is a cation, X is a non-metal (usually P, Si, B, As or S) and Y is a transition metal (usually Mo, W or V). It was long believed that the ratio x:y was confined to the range 9Fx:yF12 due to the earliest structure determinations [1,2]. In 1971, Petterson found indications for the existence of diphosphopentamolybdate anions, x:ys2.5, in a careful study of aqueous heteropolyanion systems [3]. Later structures such as Na6[P2Mo5O23]P13H2O, Na4[H2P2Mo5O23]P10H2O and (NH4)5[HP2Mo5O23]P U
Corresponding authors.
3H2O were determined [4–6], providing evidence for this. Hori et al. determined the structure of Na[N(CH3)4]3[S2Mo5O23]P4H2O and published a review of the structures of heteropolyacids salts for which the ratio x:y is 2.5 [7]. A polymeric nickel complex with formula (NH4)8Ni[(HP2Mo5O23)2]P12H2O has been described [8]. Recently, a novel conjunction of hetero(macro)cycles and a diphosphopentamolybdate cage has been achieved by the synthesis of the first examples of polyoxomolybdate cages derivatized with hetero(macro)cycles with general formula [(ZP)2Mo5O21]2y [9]. In the last years, there is much current interest in the way molecules and ions are organized in the solid state to form novel materials with improved electrical, optical, magnetic or catalytic properties. In this respect, although there have been theoretical studies on packing interactions in simple organic systems, up to now, very few systematic reports have been published analyzing correlations between the character-
0020-1693/97/$17.00 q 1997 Elsevier Science S.A. All rights reserved PII S0020-1693(96)05201-2
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istic of the individual components (ions or neutral molecules) and the way in which a crystalline inorganiccompound is constructed and organized. This research would be of particular importance in the field of polyoxometalate chemistry, since this kind of compound is used as a catalyst and the features of organic cations play an important role not only in the crystal packing determination but also in the catalytic properties such as particle size, porosity and thermal stability [10]. In this context, during our studies on the chemistry of organic salts of iso- and heteropolyoxometalates, we have chemically and structurally characterized four salts of phosphopolyoxometalates with an x:y ratios2.5: the hexakis(4-aminopyridinium)diphosphopentamolybdate(VI)pentahydrate (1), tris(ethylenediammonium) diphosphopentamolybdate(VI) hexahydrate (2), aluminium tetrakis(3-aza1,5-pentamethylenediammonium) bis[hydrogendiphosphopentamolybdate(VI)] chloride decahydrate (3) and tetrakis(t-butylammonium) dihydrogendiphosphopentamolybdate(VI) pentahydrate (4). The choice of the organoamine bases was determined by the presence of amino groups capable of establishing strong hydrogen bonds which involve the oxygen atoms as acceptors and stabilize the crystal structure of this kind of compound. Second, it is well known that cation features, such as length, size and number of amino groups, play an important role in the crystal packing of polyoxometalate salts. The aim of our work is to study the influence of the cation characteristic and the protonation degree of the polyanion on the structural unit interactions and — as a consequence — on the crystal organization in these phosphomolybdate species with a 2.5 x:y ratio. 2. Results and discussion 2.1. Syntheses and spectroscopic characterization
Isolation of polyanions from solution can be achieved by addition of alkylamines or aromatic amines as counterions
[11–15] that provide groups which may participate in an extensive network of hydrogen bonding with either oxygen atoms from the polyanions or from water molecules playing an important role in the photochemical properties [16–18] of this kind of compound. In the present work we have employed 4-aminopyridine, ethylenediamine, diethylenetriamine and t-butylamine organic bases in order to study the differences present in the crystal structure due to cation– cation and cation–anion interactions. IR spectroscopy is a good method for identifying the type of polyanion and the presence of protonated organic cations. As expected on the basis of the literature the bands corresponding to the heteropolyanions are detectable in the 1300–400 cmy1 range (Table 1) and the presence of well differentiated Mo–O and P–O linkages in the heteropolyanion structure indicates the possibility of a great number of internal vibrations [19]. 2.2. Structures of compounds 1–4
The asymmetrical units of the compounds contain: six 4-aminopyridinium cations, five water molecules and one diphosphopentamolybdate(VI) anion for compound 1; three ethylenediammonium cations, six water molecules and one diphosphopentamolybdate(VI) anion for compound 2; one aluminium, on a two-fold crystallographic axis, two 3-aza1,5-pentamethylenediammonium cations, one chloride anion, 50% population, five water molecules and one hydrogendiphosphopentamolybdate(VI) anion for compound 3; six t-butylammonium cations, five water molecules and one dihydrogendiphosphopentamolybdate(VI) anion for compound 4. The diphosphopentamolybdate anion, [HnP2Mo5O23](6yn)y, is built up of five MoO6 octahedra and two PO4 tetrahedra. The octahedra form a pentagonal ring by sharing four edges and one corner. The PO4 tetrahedra are attached each one to one side of the ring by three oxygen atoms (Fig. 1). Mo–
Table 1 Analytical and spectroscopical data of compounds 1–4 Compound
Analysis (%) C
(C5H7N2)6[P2Mo5O23]P5H2O (1) (C2H10N2)3[P2Mo5O23]P6H2O (2) Al(C4H15N3)4[HP2Mo5O23]2P10H2O (3) (C4H12N)4[H2P2Mo5O23]P5H2O (4) a
H
IR data (cmy1) N
22.7 3.1 10.6 (22.94) (3.34) (10.58) 5.95 3.5 (5.99) (3.50) 7.6 3.5 (7.73) (3.33) 14.9 4.55 (14.80) (4.66)
6.6 (6.98)
d(P–OH)
n (P–Ot)
n (P–Ob)
n (Mo–Ot)
n (Mo–Ob)
Breathing a
1280w 1200m 1090vs 1100s 1085s
1035vs 995s
945m(sh)
890vs 830s(sh)
695vs 675vs
1030s 1005m
975w 915vs
685s(br)
1045m 995m 1065s 1005s
975vs
895sh 870sh 830w 895vs
930vs
900vs
6.4 1275w 1100s (6.76) 4.1 1295w 1100s (4.32) 1210w(br)
715vs(br) 690vs(br) 700vs(br)
Breathing of polyanion.
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Table 2 Mo∆Mo, Mo∆P and P∆P distances (A˚) and Mo–O and P–O bond lengths (A˚) for compounds 1–4
Fig. 1. ORTEP view (thermal ellipsoids at the 50% probability level) of the [HnP2Mo5O23](6yn)y polyanion with atom labelling. For compound 3, the O22 atom is protonated and for compound 4, both the O22 and O23 atoms are protonated.
Mo, Mo–P distances and Mo–O and P–O bond lengths are given in Table 2. Each octahedra has four bridge oxygen atoms and two terminal oxygen atoms. There are two types of Mo–Mo distances: (a) those between octahedra sharing edges (3.319–3.402 A˚); (b) between octahedra sharing corners which are significantly longer (3.671–3.677 A˚). Mo–P distances are in the range 3.311–3.641 A˚. P–P distances are 3.802, 3.793, 3.781 and 3.756 A˚ respectively, for compounds 1–4. The Mo–O bond lengths can be classified into three groups: (i) short, Mo–Ot, 1.692–1.728 A˚; (ii) medium, Mo–Ob, oxygen atoms being shared by two molybdenum atoms, 1.891– 1.958 A˚; (iii) long, Mo–Ob, oxygen atoms being shared by phosphorus and molybdenum atoms, 2.170–2.468 A˚. Each molybdenum atom has two short distances with terminal oxygen atoms, two medium distances and two long ones. The tetrahedral coordination around phosphorus is almost regular, with P–O bond distances ranging between 1.504 and 1.572 A˚. In the non-protonated polyanion the P–O bond distance to the unshared oxygen atom (Ot) is shorter than those involving the oxygen atoms shared by the molybdenum atoms. In compounds 3 and 4 a lengthening of the P–Ot bond distance can be observed for the protonated oxygen. This is in accordance with crystal structures previously reported. Although the polyanions for all four compounds show a similar geometry, the degree of protonation leads to distinguishable features. Polyanions of compounds 1–4 have been compared with other organic and inorganic diphosphopentamolybdate salts previously published (Table 3). The molybdenum atoms of the pentagonal ring are nearly on the same plane and no significant deviations are observed as a consequence of the protonation degree. However, the influence of the protonation is clearly visible in the P–P distances. The higher the protonated state is, the shorter the P–P distance gets. This fact is clearly observable in the sodium salts for which the P–P distances range from 3.824 to 3.707 A˚ in unprotonated and diprotonated anions, respectively. Attachment of a hydrogen atom to one of the terminal oxygen atoms
Mo1–Mo2 Mo2–Mo3 Mo3–Mo4 Mo4–Mo5 Mo5–Mo1 P1–Mo1 P1–Mo2 P1–Mo3 P1–Mo4 P1–Mo5 P2–Mo1 P2–Mo2 P2–Mo3 P2–Mo4 P2–Mo5 P1–P2 Mo1–O1 Mo1–O6 Mo1–O11 Mo1–O15 Mo1–O18 Mo1–O21 Mo2–O2 Mo2–O7 Mo2–O11 Mo2–O12 Mo2–O18 Mo2–O19 Mo3–O3 Mo3–O8 Mo3–O12 Mo3–O13 Mo3–O16 Mo3–O19 Mo4–O4 Mo4–O9 Mo4–O13 Mo4–O14 Mo4–O17 Mo4–O20 Mo5–O5 Mo5–O10 Mo5–O14 Mo5–O15 Mo5–O20 Mo5–O21 P1–O17 P1–O19 P1–O21 P1–O22 P2–O16 P2–O18 P2–O20 P2–O23
1
2
3
4
3.384(1) 3.378(1) 3.671(1) 3.366(1) 3.369(1) 3.496(2) 3.379(2) 3.623(1) 3.319(2) 3.534(2) 3.493(2) 3.569(2) 3.311(2) 3.611(1) 3.423(2) 3.802(2) 1.719(5) 1.715(5) 1.900(5) 1.911(4) 2.329(4) 2.331(4) 1.705(6) 1.718(5) 1.933(4) 1.943(4) 2.429(5) 2.173(4) 1.704(5) 1.710(5) 1.956(4) 1.933(4) 2.174(5) 2.349(4) 1.729(5) 1.723(6) 1.908(4) 1.927(4) 2.226(5) 2.345(4) 1.714(5) 1.711(5) 1.945(4) 1.931(4) 2.192(4) 2.372(4) 1.517(4) 1.563(4) 1.569(4) 1.522(5) 1.537(4) 1.556(4) 1.570(5) 1.512(5)
3.3500(6) 3.3197(6) 3.6656(6) 3.3782(6) 3.3813(5) 3.438(1) 3.446(1) 3.601(1) 3.322(1) 3.547(1) 3.498(1) 3.517(1) 3.304(1) 3.585(1) 3.391(1) 3.793(2) 1.714(3) 1.709(3) 1.901(3) 1.924(3) 2.355(3) 2.284(2) 1.726(3) 1.706(3) 1.957(3) 1.901(3) 2.294(3) 2.221(2) 1.728(3) 1.715(3) 1.922(3) 1.917(3) 2.213(2) 2.340(3) 1.717(3) 1.707(3) 1.909(3) 1.951(3) 2.205(3) 2.339(2) 1.727(3) 1.701(3) 1.950(2) 1.932(3) 2.170(3) 2.383(3) 1.524(3) 1.557(2) 1.557(3) 1.521(3) 1.517(3) 1.568(3) 1.561(3) 1.511(3)
3.402(1) 3.344(1) 3.676(6) 3.379(1) 3.387(1) 3.455(3) 3.399(3) 3.546(3) 3.300(3) 3.572(3) 3.482(3) 3.588(3) 3.320(3) 3.641(3) 3.435(3) 3.781(3) 1.696(8) 1.716(8) 1.902(7) 1.917(7) 2.363(7) 2.312(7) 1.702(7) 1.713(8) 1.937(7) 1.933(7) 2.468(6) 2.223(6) 1.710(7) 1.721(7) 1.910(7) 1.897(6) 2.298(7) 2.271(7) 1.715(7) 1.692(8) 1.921(6) 1.913(7) 2.275(7) 2.418(7) 1.700(7) 1.709(8) 1.932(7) 1.935(7) 2.233(7) 2.387(6) 1.513(8) 1.545(7) 1.552(7) 1.526(7) 1.504(7) 1.521(7) 1.518(7) 1.564(7)
3.384(1) 3.383(1) 3.677(1) 3.348(1) 3.393(1) 3.487(2) 3.424(2) 3.616(2) 3.343(2) 3.517(2) 3.441(2) 3.515(2) 3.341(2) 3.592(2) 3.414(2) 3.756(2) 1.704(4) 1.696(6) 1.921(5) 1.910(5) 2.310(3) 2.347(4) 1.694(6) 1.701(6) 1.925(4) 1.933(4) 2.367(4) 2.212(4) 1.704(5) 1.706(4) 1.921(5) 1.891(4) 2.335(4) 2.388(3) 1.712(4) 1.700(5) 1.899(4) 1.904(3) 2.348(4) 2.337(4) 1.702(4) 1.696(6) 1.926(4) 1.948(4) 2.224(3) 2.357(4) 1.512(4) 1.538(4) 1.536(4) 1.557(5) 1.512(3) 1.529(4) 1.535(4) 1.562(5)
implies an elongation of the P–Ot distance and a shortening of the remaining P–O bond distances. Although, the crystal packing for all four compounds 1–4 shows some common basic features, the most notable being
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Table 3 Distance from the respective ring plane of molybdenum and phosphorus atoms (A˚) and the orientation of the P–P vectors to the ring (8) Compound
Mo1
Mo2
(C5H7N2)6[P2Mo5O23]P5H2O (1) (C2H10N2)3[P2Mo5O23]P6H2O (2) Na6[P2Mo5O23]P14H2O Na6[P2Mo5O23]P13H2O Al(C4H15N3)4[HP2Mo5O23]2ClP10H2O (3) Na5[HP2Mo5O23]P11H2O (NH4)5[HP2Mo5O23]P3H2O (NH4)8Ni[HP2Mo5O23]2P12H2O (C4H12N)4[H2P2Mo5O23]P5H2O (4) Na4[H2P2Mo5O23]P10H2O [C(NH2)3]4[H2P2Mo5O23]PH2O
0.025 0.045 0.010 0.000 y0.008 0.018 0.024 y0.057 0.016 y0.002 0.056
y0.189
0.115 0.200 0.153 y0.159 0.120 0.126 0.197 y0.151 0.165 y0.180
Mo3 0.264
y0.213 y0.315 y0.232
0.249
y0.196 y0.210 y0.245
0.214
y0.248
0.221
the extensive hydrogen bonding network, several significant differences in each crystal organization can be noticed. 2.2.1. Crystal packing in compound 1
The diphosphopentamolybdate anions are located in two
z levels, zs1/4 and zs3/4, parallel to the [100] direction
(Fig. 2). Anions, organic cations and water molecules are joined by a three-dimensional network of hydrogen bonds of types: N–H∆O (2.653–3.228 A˚), N–H∆Ow (2.818–3.420 A˚), Ow–Hw∆O (2.824–3.115 A˚) and Ow–Hw∆Ow (2.765–2.997 A˚). It is interesting to note the distribution of aromatic cations in the unit cell leading to a great number of p–p interactions [23]. The presence of this type of interaction has been evaluated [24] and the results are shown in Table 4. Three face-to-face (P) interactions and two edgeon (T) ones have been found. The face-to-face stacked cations are offset one from another and show a staggered orientation, presumably to minimize electrostatic repulsions
Mo4 y0.250
0.238 0.320 0.232 y0.251 0.207 0.225 0.207 y0.206 0.248 y0.186
Mo5 0.150
y0.184 y0.216 y0.153
0.169
y0.149 y0.166 y0.103
0.127
y0.163
0.089
P1 y1.887
1.907 y1.890 y1.918 y1.858 y1.873 1.895 1.870 y1.885 y1.844 y1.869
P2 1.904
y1.886
1.885 1.904 1.930 1.851 y1.861 y1.899 1.859 1.862 1.909
8
P∆P
Ref.
89.23 88.97 89.45 88.25 89.63 88.15 89.91 89.18 89.06 88.95 89.74
3.791 3.793 3.776 3.824 3.781 3.726 3.756 3.770 3.744 3.707 3.778
this work this work [20] [4] this work [21] [6] [8] this work [5] [22]
and steric hindrances between the ammonium and amine groups. Although face-to-face stacking geometry is disfavored by p–p repulsion, the presence of a positively charged atom, the nitrogen atom of the aromatic ring, leads to these three interactions. It is important to notice the strong interaction between cations Xs6, with a clear overlapping of the aromatic rings. The p–p interactions in the edge-ongeometry take place through the carbon atoms, CX2 and CX3 of the vertical T-group. 2.2.2. Crystal packing in compound 2
The diphosphopentamolybdate anions are arranged in layers perpendicular to the [1# 01] direction (Fig. 3). There is no direct interaction between polyanions belonging to different layers, even though the shortest O∆O distance is 3.365 A˚ between two terminal oxygens O23. The ethylenediammonium cations, with a gauche conformation, and water molecules are located between layers and participate in the
Fig. 2. View along the [010] direction of compound 1.
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Table 4
p-p Interactions in compound 1
Cations
DC
ANG
DZ
DXY
DS
ANGS
RON
Type
1-2 1-3 3-1 5-3 6-6
5.05 4.20 4.20 5.43 3.48
74.3 4.6 4.6 80.0 0.0
4.73 3.60 3.50 4.89 3.48
1.79 2.16 2.32 2.36 0.12
3.76 3.60 3.58 3.69 4.13
103.4 91.6 89.2 134.4 57.5
2.1 16.1 16.1 13.9 0.0
T P P T P
DC: distance between the centroids of the aromatic groups i and j. ANG: angle between the least-squares planes of the two centroids. DZ: distance between the centroid of the i group and the least-squares plane of j. DXY: distance between the centroids of i and j projected onto the least-squares plane of i. DS: distance from the centroid of i to the nearest hydrogen atom of the j group. ANGS: (centroid of i-nearest hydrogen atom of the j group-centroid of j) angle. RON: (ipso carbene of i-centroid of i-centroid of j-nearest hydrogen atom of j) torsion angle.
Fig. 3. Packing in compound 2.
formation of an extensive network of hydrogen bonds of types N–H∆O (2.722–3.151 A˚), N–H∆Ow (2.783–3.165 A˚), Ow–Hw∆O (2.740–3.002 A˚) and Ow–Hw∆Ow (2.713– 2.785 A˚). 2.2.3. Crystal packing in compound 3 The crystal structure of 3 projected onto the (001) plane
is shown in Fig. 4. The hydrogendiphosphopentamolybdate anions are located in two x levels, xs0 and xs1/2. The pentagonal molybdate framework of the anions is located parallel to the (010) plane with the P–P vectors parallel to the [010] direction. The formation of strong hydrogen bonding (d(O∆O)s2.529 A˚) [25] between the protonated terminal oxygen atom O23 and the non-protonated oxygen atom O22 of the adjacent polyanion through the hydrogen atom H1 favors the polymeric disposition of the [HP2Mo5O23]5y polyanions along the b axis. The organic cations occupy the space among the polyanions. One of the 3-aza-1,5-diethylenediammonium cations (Xs1), with a trans configuration, is situated along the [001] direction. The other 3-aza-1,5-diethylenetriammonium cation (Xs2), with gauche–trans–trans–gauche
configuration, is located surrounding two adjacent diphosphopentamolybdate(VI) anions and joining them together by hydrogen bonds that involve the three N atoms. Cations, anions and water molecules are positioned so as to be able to join themselves via hydrogen bonding, N–H∆O (2.727– 3.182 A˚), N–H∆Ow (2.651–2.919 A˚), O–H∆O (2.529 A˚), Ow–Hw∆O (2.728–3.359 A˚), Ow–Hw∆Ow (2.765 A˚), N–H∆Cl (3.071 A˚) and Ow–H∆Cl (3.002 A˚). 2.2.4. Crystal packing in compound 4 The crystal structure of 4 is shown
in Fig. 5. Each [H2P2Mo5O23]4y anion is joined with the two adjacent polyanions by means of strong hydrogen contacts of the type O–H∆O (O22∆O17s2.591 and O23∆O16s2.596 A˚) [25], forming chains parallel to the [001] direction. This catenary arrangement is reinforced with other hydrogen bonds that involve the water molecules and the cations Xs1 (N11) and Xs3 (N31). Anions placed in different chains are joined through the water molecules O24w and O25w. The hydrophobic groups of the t-butylammonium cations are directed towards the regions ys0 and xs1/2. The different hydrogen bonds within the structure can be classified into
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the total organic cation pyrolysis and the inorganic residue evolution. For compounds 1, 2 and 4, final residues were identified by their X-ray powder diffraction patterns as a mixture of MoO3 and P2O5 in an approximate 5:1 ratio. However, other peaks are observed in the diffractograms which could not be identified but they may be attributable to phosphomolybdo species. For compound 3, several peaks corresponding to Al2O3 can also be detected. 3. Conclusions
Fig. 4. View along the [001] direction of compound 3. Down: a axis; right: b axis.
The crystallographic study of the diphosphopentamolybdate salts reported here, together with the ones previously published, reveal that the protonated or unprotonated state of the diphosphopentamolybdate anion and the type of counterion have a strong influence on the crystal packing of the diphosphopentamolybdate salts (Table 5). The salts of the unprotonated diphosphopentamolybdate anion present a crystal packing based on polyanion layers whereas monoprotonated and diprotonated anions lead to a catenary arrangement of polyanions through hydrogen bonds, involving the terminal oxygen atoms of the PO4 groups, such as Ot–H∆Ot for monoprotonated or Ot–H∆Op for diprotonated anions. Although this fact is always observed whenever an organic counterion is used, some specific considerations must be pointed out if an inorganic counterion like Naq is present. This cation induces the formation of a catenary arrangement of polyanions through its coordination sphere no matter the protonation state. 4. Experimental 4.1. Materials and methods
Fig. 5. View along the [100] direction of compound 4.
five types: N–H∆O (2.879–3.351 A˚), N–H∆Ow (2.799– 3.340 A˚), O–H∆O (2.591–2.596 A˚), Ow–Hw∆O (2.808– 3.190 A˚) and Ow–Hw∆Ow (2.760–3.050 A˚). Similar hydrophobic zones have been found in the crystal structure of other t-butylammonium polyoxometallates [26]. 2.3. Thermal analysis
The thermal behavior of the compounds was studied under dynamic air atmosphere. All the compounds are quite stable and their thermal degradation starts with the loss of the crystallization water molecules during several overlapped endothermic processes which take place between 50 and 135 8C. The anhydrous compounds are stable up to around 200 8C beyond which the thermal decompositions are followed by
All reagents were purchased from Merck and were used without further purification. C, H and N analyses were performed on a Perkin-Elmer 240 analyzer. The densities were measured by flotation in CHBr3/CCl4. IR spectra were recorded in the 4000–400 cmy1 range on a Nicolet 740 FTIR spectrometer, and the solid compounds were mixed with fused potassium bromide and pressed into transparent disks. A Setaram TAG 24 S16 thermobalance was used to obtain the differential thermal analysis (DTA) and thermogravimetric analysis (TGA) curves, simultaneously, in an argon– oxygen atmosphere (4:1) with a heating rate of 5 8C miny1. 4.2. Preparation of (C5H7N2)6[P2Mo5O23]P5H2O (1)
Colorless single crystals of 4-aminopyridiniumdiphosphopentamolybdate(VI) pentahydrate were obtained from a solution prepared by adding 4-aminopyridine (0.35 g, 3.5 mmol) to a solution of Na2MoO4P2H2O (2.5 g, 10.3 mmol) and Na2HPO4P2H2O (0.50 g, 3.5 mmol) in water (200 ml),
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Table 5 Packing study of the diphosphopentamolybdate salts Compound
Cation
Packing
L∆L a
(C5H7N2)6[P2Mo5O23]P5H2O (1) (C2H10N2)3[P2Mo5O23]P6H2O (2) Na6[P2Mo5O23]P14H2O
C5H7N2q C2H10N22q Naq
8.3 7.7
Na6[P2Mo5O23]P13H2O
Naq
layers parallel to [001] layers parallel to (1# 10) chains Mo–O∆Na∆O–Mo parallel to [010] layers parallel to (1# 20) chains Mo–O∆Na∆O–Mo in zigzag parallel to [001] layers parallel to (100)
Al(C4H15N3)4[HP2Mo5O23]2ClP10H2O (3) Na5[HP2Mo5O23]P11H2O
C4H15N32q, Al3q Naq
(NH4)5[HP2Mo5O23]P3H2O (NH4)8Ni[HP2Mo5O23]P12H2O
NH4q NH4q, Ni2q
(C4H12N)4[H2P2Mo5O23]P5H2O (4) Na4[H2P2Mo5O23]P10H2O
C4H12Nq Naq
[C(NH2)3]4[H2P2Mo5O23]PH2O
C(NH2)3q
a b
chains P2–Ot–H∆Ot–P1 parallel to [010] chains P2–Ot–H∆Ot–P1 parallel to [001] layers parallel to (100) chains P1–Ot–H∆Ob–P2 parallel to [101] chains P2–Ot–H∆Ob–P2 and P1–Ot–Ni– Ot–P1 parallel to [101] chains P–Ot–H∆Ob–P parallel to [001] chains Mo–O∆Na∆O–Mo in zigzag perpendicular to [001] layers parallel to (100) chains P–Ot–H∆Ob–P parallel to [100]
O∆O b
Ref.
5.5
this work this work [20]
8.2
9.1
7.3
[4] 2.54 2.56
this work [21]
2.57 2.66
[6] [8]
2.53 5.23
this work [5]
2.56
[22]
Distance between adjacent layers of polyanion. Shortest distance between oxygen atoms from adjacent polyanions in the same chain.
Table 6 Crystallographic details for compounds 1–4 Compound Formula weight Crystal system Space group ˚) a (A ˚) b (A ˚) c (A a (8) b (8) g (8) ˚ 3) V (A Do (g cmy3) Dx (g cmy3) Z F(000) m (l Mo Ka) (cmy1)
Diffractometer Crystal size (mm) Radiation (Mo Ka) (A˚) Temperature (K) u Range (8) Range of h; k; l No. unique reflections No. observed reflections No. variables R Rw
1
2
3
4
1570.45 monoclinic P21/n 13.891(4) 18.621(2) 21.345(1) 90 103.96(1) 90 5358(2) 1.96(1) 1.947 4 3120 12.63 CAD4 0.50=0.40=0.30 0.71069 293(1) 2–25 0,16; 0,22; y25,25 9232 6688 (IG3s (I)) 739 0.036 0.041
1204.06 triclinic P1# 10.409(3) 11.683(1) 13.968(1) 100.50(1) 99.55(1) 89.93(1) 1646.3(5) 2.42(1) 2.429 2 1184 20.14 CAD4 0.70=0.45=0.10 0.71069 293(1) 1–30 0,14; y16,16; y19,19 9691 8460 (IG3s (I)) 524 0.033 0.046
2484.60 monoclinic I2/a 20.330(2) 16.754(2) 21.606(3) 90 95.11(3) 90 7330(2) 2.23(1) 2.252 4 4880 18.58 Philips PW1100 0.50=0.10=0.10 0.71069 294(1) 2–22 0,22; 0,18; y22,22 4493 3634 (IG3s (I)) 453 0.050 0.052
1298.31 triclinic P1# 12.511(2) 13.216(2) 14.465(3) 107.36(4) 100.69(3) 96.16(2) 2209.2(9) 1.94(1) 1.950 2 1296 15.06 CAD4 0.15=0.15=0.28 0.71069 293(1) 1–30 0,17; y18,18; y20,20 12855 8239 (IG3s (I)) 488 0.037 0.044
previously mixed with stirring during half an hour at room temperature until dilution. HCl 6.0 M was added to bring the solution to the pH value of 6. Crystals were filtered off, washed with diethyl ether and then carefully dried in air.
4.3. Preparation of (C2H10N2)3[P2Mo5O23]2P6H2O (2)
To an aqueous solution (200 ml) of Na2MoO4P2H2O (4.84 g, 20.0 mmol) and Na2HPO4P2H2O (0.76 g, 4.3
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Table 7 Atomic parameters for compound 1
Table 7 (continued) Atom
Atom
x
y
z
Mo1 Mo2 Mo3 Mo4 Mo5 P1 P2 O1 O2 O3 O4 O5 O6 O7 O8 O9 O10 O11 O12 O13 O14 O15 O16 O17 O18 O19 O20 O21 O22 O23 O24w O25w O26w O27w O28w N11 C12 C13 C14 C15 C16 N17 N21 C22 C23 C24 C25 C26 N27 N31 C32 C33 C34 C35 C36 N37 N41 C42 C43 C44 C45
0.73698(4) 0.55115(4) 0.38293(4) 0.43886(4) 0.67252(4) 0.48838(10) 0.61576(11) 0.77824(33) 0.47927(34) 0.28491(31) 0.33897(33) 0.69971(32) 0.83213(31) 0.62746(36) 0.33450(32) 0.46600(35) 0.73808(35) 0.64084(29) 0.45957(30) 0.37549(29) 0.54313(29) 0.76329(30) 0.52130(28) 0.42476(30) 0.65296(28) 0.47601(28) 0.58701(28) 0.60004(28) 0.45669(30) 0.69490(30) 0.29926(44) 0.97887(41) 0.81674(43) 0.29781(47) 0.23109(57) 0.76480(49) 0.76181(57) 0.67569(51) 0.58795(57) 0.59271(67) 0.67843(63) 0.50266(43) 0.67080(48) 0.62735(68) 0.61362(71) 0.64656(57) 0.69398(78) 0.70340(79) 0.62890(61) y0.10864(48) y0.04362(66) 0.04965(58) 0.09071(54) 0.02202(58) y0.07370(68) 0.18750(43) 0.03016(55) 0.12770(65) 0.16277(53) 0.10214(57) 0.00207(58)
0.24982(3) 0.13546(3) 0.22370(3) 0.41439(3) 0.41688(3) 0.30051(8) 0.27702(8) 0.27161(26) 0.09161(25) 0.20721(26) 0.46647(25) 0.45849(23) 0.19785(25) 0.07027(24) 0.20186(26) 0.44927(27) 0.46501(24) 0.17919(22) 0.13719(22) 0.32723(22) 0.46158(21) 0.33672(22) 0.24819(23) 0.36280(22) 0.22272(21) 0.23880(21) 0.34953(20) 0.32419(21) 0.27481(23) 0.29041(23) 0.38174(31) 0.24390(33) 0.47877(35) 0.41922(36) 0.33628(39) 0.26957(37) 0.33553(43) 0.37509(41) 0.34500(38) 0.27439(45) 0.23914(43) 0.38032(36) 0.40767(34) 0.40442(44) 0.46386(46) 0.53063(41) 0.53215(44) 0.47034(52) 0.59108(42) 0.30154(44) 0.25180(52) 0.26586(44) 0.33109(43) 0.38027(51) 0.36355(55) 0.34368(39) 0.32634(42) 0.32448(49) 0.37033(46) 0.42355(39) 0.42524(50)
0.36898(2) 0.30221(3) 0.18733(2) 0.22164(3) 0.31391(2) 0.34489(7) 0.20728(7) 0.44927(21) 0.34451(23) 0.22080(22) 0.22805(24) 0.38783(21) 0.35582(23) 0.28407(24) 0.10813(21) 0.15327(22) 0.26983(22) 0.37551(19) 0.21732(20) 0.18725(20) 0.28447(19) 0.32861(19) 0.16124(19) 0.31317(19) 0.26341(18) 0.29393(18) 0.23580(18) 0.36352(18) 0.40455(20) 0.17078(20) 0.72326(30) 0.52502(25) 0.70942(34) 0.38880(33) 0.59664(33) 0.88280(32) 0.85853(38) 0.84456(40) 0.85348(37) 0.87949(46) 0.89157(45) 0.83784(40) 0.09129(31) 0.02982(44) y0.00855(36) 0.01879(35) 0.08357(41) 0.11815(38) y0.01717(36) 0.21198(38) 0.19744(54) 0.20709(46) 0.23626(38) 0.25024(48) 0.23912(48) 0.24943(36) y0.00859(33) 0.02430(40) 0.07357(40) 0.08909(35) 0.05354(43) (continued)
C46 N47 N51 C52 C53 C54 C55 C56 N57 N61 C62 C63 C64 C65 C66 N67
x
y
y0.02610(61)
0.13838(50) 0.47719(69) 0.56356(88) 0.62568(60) 0.59399(59) 0.49678(76) 0.44544(104) 0.65409(53) 0.87618(77) 0.85600(75) 0.90612(66) 1.00198(71) 1.02339(63) 0.96173(85) 1.05288(75)
0.37634(59) 0.47343(38) 0.44842(56) 0.42473(54) 0.39166(48) 0.38315(42) 0.40386(73) 0.43938(86) 0.35600(42) 0.57505(73) 0.50862(56) 0.46860(54) 0.50321(63) 0.57063(44) 0.60211(78) 0.47247(59)
z
0.00582(45) 0.13466(37) 0.61143(50) 0.64171(48) 0.60947(39) 0.54258(35) 0.51289(54) 0.54843(79) 0.50946(33) 0.50193(41) 0.52359(47) 0.57089(40) 0.60520(44) 0.58452(39) 0.53379(54) 0.64970(45)
mmol), 0.50 ml (7.5 mmol) of ethylenediamine was added dropwise with stirring. The final pH was adjusted to a value of 6 by using HCl (2.0 M). A white precipitate, identified as compound 2 appeared after 3 weeks. Single crystals can be obtained by recrystallization in water. 4.4. Preparation of Al(C4H15N3)4[HP2Mo5O23]2ClP10H2O (3)
This compound was prepared by the same method as for adding the diethylenetriamine (0.40 ml, 3.5 mmol) to a solution of Na2MoO4P2H2O (5.0 g, 20.6 mmol) and Na2HPO4 (0.50 g, 3.5 mmol) in water (200 ml). HCl was added to bring the pH to 3. Crystals of 3 appeared after two weeks. They were filtered off, washed with diethyl ether, and then dried in open air for a few hours. The presence of aluminium in this compound was determined by EDAX and the atomic absorption technique was used in order to find the reactant with aluminium impurities. In the Na2MoO4 compound impurities of aluminium were detected. 1,
4.5. Preparation of (C4H12N)4[H2P2Mo5O23]2P5H2O (4) Method A. Solutions of t-butylammonium molybdate (2.0 g, 6.5 mmol) in 50 ml of water and 2.0 ml of H3PO4 (1:10 dilution) were mixed and HCl (3.0 M) was added to bring the pH;3. After two weeks prismatic crystals were obtained. Method B. To an aqueous solution (10 ml) of Na2MoO4P2H2O (5.0 g, 20.6 mmol) were added 5.5 ml (82 mmol) of H3PO4 (85%). The resulting solution was refluxed with stirring for 2 h. Several drops of Br2 were added to remove the pale-green color of the solution. Then 5.5 g (50 mmol) of t-butylammonium chloride were added. Very nice colorless single crystals of compound 4 appeared overnight. 4.6. Crystallography
Crystal data and experimental detail of the four samples are displayed in Table 6. Lattice constants were determined
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Table 8 Atomic parameters for compound 2
Table 9 Atomic parameters for compound 3
Atom
x
y
z
Mo1 Mo2 Mo3 Mo4 Mo5 P1 P2 O1 O2 O3 O4 O5 O6 O7 O8 O9 O10 O11 O12 O13 O14 O15 O16 O17 O18 O19 O20 O21 O22 O23 O24w O25w O26w O27w O28w O29w N11 C12 C13 N14 N21 C22 C23 N24 N31 C32 C33 N34
0.09534(3) 0.26776(3) 0.42042(3) 0.27569(3) 0.12341(3) 0.08777(7) 0.38945(8) y0.06924(29) 0.19944(27) 0.34794(27) 0.22398(29) y0.04092(30) 0.16198(36) 0.33195(29) 0.58094(26) 0.40325(28) 0.19702(34) 0.10307(24) 0.41929(25) 0.36869(25) 0.14357(24) 0.14362(26) 0.48260(23) 0.11555(23) 0.30823(23) 0.21121(22) 0.29554(23) 0.05914(24) y0.02941(24) 0.45837(27) 0.91723(31) 0.46633(34) 0.86146(38) 0.42261(39) 0.72843(66) 0.23381(122) 0.69649(31) 0.67276(42) 0.61308(44) 0.49084(36) 0.81489(36) 0.68838(41) 0.70364(44) 0.75753(34) 0.22478(38) 0.14561(46) 0.00504(49) y0.05931(37)
0.32922(2) 0.08760(2) 0.03782(2) 0.23230(2) 0.43264(2) 0.12902(7) 0.31450(7) 0.34457(27) y0.04865(23) y0.09845(23) 0.16642(26) 0.45729(29) 0.39254(27) 0.13165(26) 0.01052(25) 0.31969(26) 0.56214(26) 0.16845(22) 0.04298(24) 0.10985(22) 0.34993(22) 0.45074(22) 0.22045(22) 0.13116(22) 0.27211(21) 0.08411(21) 0.32884(22) 0.25455(21) 0.04898(23) 0.42816(22) 0.27485(28) 0.27240(30) 0.05015(36) 0.49104(34) 0.45357(47) 0.53851(99) 0.39145(30) 0.27278(36) 0.27369(39) 0.34077(31) 0.08112(29) 0.11714(43) 0.22385(41) 0.20025(36) 0.15089(36) 0.25598(41) 0.22373(42) 0.16651(34)
y0.07776(2) y0.07156(2) y0.26509(2) y0.42928(2) y0.28445(2) y0.29227(6) y0.16892(6) y0.08268(25) y0.07791(21) y0.31097(21) y0.54991(20) y0.31314(23)
0.04016(22) 0.05028(20) y0.27150(22) y0.43747(23) y0.28561(23) y0.07021(19) y0.12687(19) y0.37773(18) y0.41533(18) y0.14242(18) y0.20015(19) y0.39567(17) y0.09625(18) y0.23256(17) y0.26516(18) y0.24315(18) y0.29777(19) y0.11704(21) 0.45810(24) 0.28878(27) 0.88833(26) 0.38008(32) 0.78842(37) 0.49496(92) y0.00526(25) 0.01463(32) 0.10539(34) 0.10577(29) y0.47766(25) y0.44687(31) y0.36669(34) y0.26734(26) 0.24773(29) 0.23748(41) 0.19875(38) 0.26675(31)
by least-squares refinement of the angular setting of 25 reflections. Intensities were collected with the v–2u scan technique. Crystal stability was monitored by recording two check reflections at intervals of 200 data for compounds 1 and 3 and every 100 reflections for compounds 2 and 4; no significant variations were detected. All data were corrected for Lorentz and polarization effects. An empirical absorption correction was applied [27].
Atom
x
y
z
Mo1 Mo2 Mo3 Mo4 Mo5 P1 P2 Al1 Cl1 O1 O2 O3 O4 O5 O6 O7 O8 O9 O10 O11 O12 O13 O14 O15 O16 O17 O18 O19 O20 O21 O22 O23 O24w O25w O26w O27w O281w O282w N11 C12 C13 N14 C15 C16 N17 N21 C22 C23 N24 C25 C26 N27 H1
0.90844(4) 0.86377(4) 1.00072(4) 1.13991(4) 1.07502(4) 0.99925(13) 0.99980(13) 0.25000(–) 0.70464(32) 0.89661(38) 0.82976(36) 0.99327(34) 1.19810(34) 1.08103(38) 0.85346(40) 0.79984(37) 1.01674(35) 1.18378(37) 1.11809(37) 0.86472(33) 0.91001(33) 1.08600(32) 1.13957(32) 0.98768(32) 1.00581(33) 1.07040(34) 0.93253(32) 0.96685(30) 1.05534(33) 0.99571(31) 0.96238(32) 1.00397(35) 0.68187(42) 0.24340(41) 0.50341(39) 0.28590(41) 0.13779(111) 0.18671(152) 0.09622(46) 0.14415(61) 0.10697(55) 0.15482(47) 0.12320(51) 0.17561(55) 0.14498(47) 0.39678(52) 0.42438(54) 0.49120(53) 0.54129(40) 0.61243(52) 0.65953(54) 0.66957(41) 1.0219(84)
0.86231(5) 0.87689(5) 0.85804(5) 0.88533(5) 0.85338(5) 0.97795(15) 0.75237(14) 0.37994(29) 0.33548(39) 0.93061(47) 0.95983(44) 0.94642(40) 0.95394(44) 0.92146(44) 0.78766(45) 0.81009(46) 0.79119(43) 0.79948(45) 0.77257(46) 0.91440(40) 0.83329(39) 0.87188(39) 0.90146(43) 0.81079(41) 0.74566(39) 0.99132(40) 0.78564(36) 0.92250(38) 0.80407(40) 0.93741(38) 1.05728(38) 0.66741(39) 0.15173(48) 0.49982(56) 0.66317(42) 0.14387(53) 0.24472(139) 0.28578(193) y0.08204(55) y0.05551(84) y0.01504(77) 0.00566(60) 0.05045(73) 0.09183(67) 0.12284(59) 0.17311(58) 0.09722(63) 0.10274(68) 0.12747(51) 0.12759(64) 0.14913(63) 0.08253(55) 0.6278(100)
0.86684(4) 0.71171(4) 0.63791(4) 0.75671(4) 0.89320(4) 0.77300(12) 0.76782(12) 0.00000(–) 0.08337(30) 0.92273(35) 0.67643(35) 0.59835(32) 0.73930(35) 0.95176(32) 0.87956(36) 0.71008(36) 0.58068(31) 0.75674(35) 0.92324(36) 0.79657(31) 0.64501(31) 0.67980(31) 0.84435(30) 0.90108(31) 0.69912(30) 0.76022(33) 0.77986(30) 0.72190(29) 0.79733(30) 0.83719(30) 0.77289(32) 0.79786(31) 0.31830(37) 0.38379(42) 0.04547(34) 0.17530(42) 0.49510(106) 0.50021(143) 0.40046(41) 0.45379(55) 0.50339(53) 0.55704(44) 0.60717(56) 0.64910(51) 0.70455(43) 0.10765(51) 0.08860(50) 0.06406(47) 0.11359(38) 0.09577(46) 0.15177(52) 0.19551(42) 0.7808(78)
The positions of Mo and P atoms were located on a Patterson map for compound 1, by using DIRDIF [28] for compound 2, and SIR88 [29] for compounds 3 and 4. The remaining non-H atoms of the structures and the hydrogen
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Article: 5201
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A. Aranzabe et al. / Inorganica Chimica Acta 255 (1997) 35–45
Table 10 Atomic parameters for compound 4 Atom
x
y
z
Mo1 Mo2 Mo3 Mo4 Mo5 P1 P2 O1 O2 O3 O4 O5 O6 O7 O8 O9 O10 O11 O12 O13 O14 O15 O16 O17 O18 O19 O20 O21 O22 O23 O24w O25w O26w O27w O28w N11 C12 C13 C14 C15 N21 C22 C23 C24 C25 N31 C32 C33 C34 C35 N41 C42 C43 C44 C45 H1 H2
0.32567(4) 0.22010(5) y0.05544(4) y0.12547(4) 0.11514(4) 0.08277(11) 0.10118(11) 0.39536(38) 0.22896(45) y0.09599(40) y0.23589(34) 0.16315(40) 0.42667(38) 0.31019(43) y0.13255(38) y0.17578(35) 0.09319(42) 0.30771(34) 0.08648(35) y0.12726(31) y0.03426(32) 0.25341(33) 0.01887(30) y0.03410(29) 0.20486(31) 0.08248(31) 0.04458(30) 0.16069(30) 0.12982(34) 0.14151(32) 0.38421(46) 0.63885(57) 0.42145(77) 0.35416(67) 0.95301(82) 0.18726(51) 0.22132(74) 0.22533(130) 0.32740(158) 0.15046(176) 0.69371(45) 0.61483(57) 0.57651(89) 0.67740(95) 0.52097(93) 0.11863(58) 0.11525(63) y0.00111(70) 0.19811(73) 0.14774(85) 0.70771(81) 0.61371(64) 0.51374(89) 0.61571(111) 0.65132(305) 0.0948(71) 0.0938(72)
0.58829(5) 0.32230(4) 0.29171(4) 0.55867(4) 0.73013(4) 0.48546(11) 0.50756(11) 0.65296(43) 0.23301(40) 0.21474(34) 0.55433(37) 0.81527(35) 0.58735(46) 0.29406(44) 0.22351(34) 0.59956(36) 0.81081(37) 0.44476(35) 0.25377(31) 0.41054(30) 0.68816(31) 0.69668(33) 0.40781(29) 0.50581(29) 0.47882(31) 0.38998(29) 0.57844(29) 0.58570(30) 0.45335(34) 0.57232(32) 0.42643(56) 0.42502(61) 0.44220(106) 0.29810(74) 0.23519(109) 0.25615(45) 0.15409(58) 0.15164(127) 0.14376(136) 0.06643(171) 0.23628(44) 0.13050(56) 0.11210(83) 0.04549(76) 0.13971(98) 0.21105(45) 0.09140(53) 0.03738(64) 0.06065(61) 0.06796(78) 0.34864(103) 0.28401(65) 0.25873(168) 0.27760(160) 0.18059(308) 0.4684(71) 0.5807(70)
0.32962(4) 0.22987(4) 0.14097(4) 0.24812(4) 0.33022(4) 0.38033(9) 0.13060(9) 0.44976(35) 0.29290(36) 0.20824(33) 0.30212(33) 0.44896(34) 0.26590(38) 0.15476(36) 0.02386(31) 0.15032(32) 0.25932(37) 0.33667(29) 0.12863(28) 0.18256(28) 0.33807(29) 0.29548(30) 0.06610(26) 0.37853(26) 0.18424(26) 0.28810(27) 0.20480(27) 0.38470(27) 0.47300(28) 0.06550(28) 0.52522(42) 0.98210(62) 0.85642(69) 0.96480(64) 0.41270(63) 0.49977(45) 0.50933(64) 0.60532(120) 0.48349(129) 0.42680(157) 0.86509(42) 0.82760(56) 0.91434(81) 0.78464(96) 0.75360(94) y0.07066(45) y0.11037(49) y0.12129(60) y0.03550(63) y0.20962(61) 0.36897(83) 0.28970(62) 0.31138(81) 0.19070(106) 0.29357(274) 0.5068(65) 0.0240(64)
atoms of the polyanions were found on successive Fourier syntheses. Anisotropic refinements were carried out by fullmatrix least-squares analyses. The hydrogen atoms of the
cations and water molecules were placed in calculated positions and assigned fixed isotropic thermal parameters.Inaddition, the hydrogen atoms belonging to the protonated anions were found in the corresponding electron density difference map and refined in their positions. Final positionalparameters are reported in Tables 7–10. Most calculations were carried out using the XRAY76 system [30] running on a MicroVAX II computer. Acknowledgements
We thank Iberduero, S.A. and UPV/EHU (Grant No. 169.310-EA134/95) for financial support. A.S.J.W. acknowledges financial support from Departamento Educacio´n (Gobierno Vasco) (Grant No. BFI 94.180 EK). References
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Journal: ICA (Inorganica Chimica Acta)
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Journal: ICA (Inorganica Chimica Acta)
Article: 5201