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2D zirconium fluorides: Synthesis, structure and NMR spectroscopy
Solid State Sciences 13 (2011) 394e398
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2D zirconium fluorides: Synthesis, structure and NMR spectroscopy A. Ben Ali a, c, *, M. Body b, M. Leblanc a, V. Maisonneuve a a
Laboratoire des Oxydes et Fluorures, UMR 6010 CNRS, Institut de Recherche en Ingénierie Moléculaire et Matériaux Fonctionnels, FR CNRS 2575, Université du Maine, Avenue Olivier Messiaen, 72085 Le MANS Cedex 9, France b Laboratoire de Physique de l’Etat Condensé, UMR 6087 CNRS, Institut de Recherche en Ingénierie Moléculaire et Matériaux Fonctionnels, FR CNRS 2575, Université du Maine, Avenue Olivier Messiaen, 72085 Le MANS Cedex 9, France c Unité de Recherche 99/UR12-30, Faculté des Sciences de Bizerte, 7021 Jarzouna, Tunisia
a r t i c l e i n f o
a b s t r a c t
Article history: Received 11 June 2010 Received in revised form 22 November 2010 Accepted 28 November 2010 Available online 2 December 2010
Two new zirconium (IV) fluorides, [H2dap]$(Zr2F10)$H2O (I) and [Hmeam]2$(Zr2F10)$H2O (II), are synthesized and characterized by X-ray diffraction, thermal techniques and NMR spectroscopy. I is triclinic (P1) with a ¼ 6.805 (1) Å, b ¼ 8.361(1) Å, and c ¼ 11.853 (2) Å, a ¼ 94.54(1) , b ¼ 105.44(1) , g ¼ 108.75(1) . II is monoclinic (C2/m) with a ¼ 10.340(6) Å, b ¼ 6.624(4) Å, c ¼ 8.758(6) Å and b ¼ 110.57 (3) . The structure determinations, performed from single crystal X-ray diffraction data, lead to the R/Rw reliability factors 0.041/0.113 for I and 0.057/0.177 for II. The structures are built up from ZrF7 and ZrF8 units in I and only ZrF8 units in II. The polyhedra share common edges in order to form two different ZrF5 layers that are also found in [H2C2H10N2]$(Zr2F10)$H2O and (H3O)2$(Zr2F10)$H2O. On heating at 145 C, [H2dap]$(Zr2F10)$H2O decomposes to give the anhydrous form [H2dap]$(Zr2F10) that undergoes two successive phase transformations at 220 C and 290 C. 19F NMR spectroscopy confirms the structural features of [H2dap]$(Zr2F10)$H2O (I): two sets of three lines with a relative intensity 1:2:2 are attributed to five bridging fluorine atoms and to five nonbridging fluorine atoms. This spectroscopy demonstrates that a noticeable substitution of F anions by hydroxyl OH groups is excluded, together with the eventual substitution of H2O by HF molecules. Ó 2010 Elsevier Masson SAS. All rights reserved.
Keywords: Fluoride Zirconate Hybrid Microwave heating Solvothermal synthesis Crystal structure Layered structure
1. Introduction High valence metal cations such as Zr4þ or Ta5þ are known to develop different coordination numbers from 6 to 8 and a large variety of geometries from octahedron to dodecahedron, bicapped trigonal prism or square antiprism [1]. In the synthesis of new hybrid compounds, this flexibility is proved to be one of the key parameters that governs the dimensionality of the inorganic sublattice. Hybrid zirconium fluorides illustrate this diversity of polyanion condensation. All dimensionalities are represented. Isolated polyhedra or large polyanions are found in 0D aminoguanidinium zirconates such as [HN4CH6]2$(ZrF6) [2,3] or [H2N4CH6]4$(Zr4F24)$ 4H2O [4] respectively. Only one 2D and one 3D compounds are known: [H2en]$[Zr2F10]$H2O [5] and (H3O)$[Hgua]5$[ZrF5]6 [6]. During the last years, we have investigated the solvothermal synthesis of such hybrid fluorides [7e9] under microwave heating. This technique allows to explore various chemical systems on large concentration domains within a short time and to establish the
crystallisation domains in the composition space. The high dimensionality phases are generally found in HF rich and amine poor compositions of the starting materials [10e12]. Attention has been mainly paid to 3D phases for their potential gas storage applications; however, it can be expected that cation exchange properties can be found in 2D phases. Hereafter, we report on the synthesis, the crystal structures and the thermal behaviour of two new bidimensional zirconium fluorides templated with bis-(1-3-diaminopropane) (dap), [H2dap]$ (Zr2F10)$H2O (I) or methylamine (meam), [Hmeam]2$(Zr2F10)$H2O (II). The ZrF4-dap-HF system is investigated in ethanol solvent under solvothermal conditions at T ¼ 190 C and the syntheses are performed in a microwave oven MDS2100 during 1h. An evaporation technique at room temperature is used for the ZrF4-meam-HF system. The starting Zr/HF molar ratio is fixed at 1/28 while the Zr/ meam ratio varies between 1/2 and 4/1. A pure phase is obtained for Zr/meam ¼ 1/1. 2. Experimental
* Corresponding author. Unité de Recherche 99/UR12-30, Faculté des Sciences de Bizerte, 7021 Jarzouna, Tunisia. Tel.: þ216 97 35 39 70; fax: þ216 72 59 05 66. E-mail address: [email protected] (A. Ben Ali). 1293-2558/$ e see front matter Ó 2010 Elsevier Masson SAS. All rights reserved. doi:10.1016/j.solidstatesciences.2010.11.044
The 2D composition space diagram of the ZrF4-dap-HF system for [Zr4þ] ¼ 0.5 mol L1, is given in Fig. 1. The positions of the points
A. Ben Ali et al. / Solid State Sciences 13 (2011) 394e398
395
Table 2 Selected inter-atomic distances (Å) in [H2dap]$(Zr2F10)$H2O (I).
Fig. 1. Composition space diagram (mol %) of the ZrF4edap-HF system for [Zr4þ] ¼ 0.5 M.
indicate the starting compositions and the labels are associated with the major phases that crystallise. Only three different phases grow and the approximate limits of their domains are indicated in Fig. 1. It is clear that an increase of the HF concentration results in the condensation of the building species and the evolution of the F/ dap ratio in the solids, from 4/1, to 6/1 and then to 10/1, is consistent with the variation of the starting compositions. At high amine concentrations, isolated (ZrF7(H2O))3- entities are observed in [H2dap]2$(ZrF7(H2O))$(F)$3H2O. The structure is not
Table 1 Crystallographic data of [H2dap]$(Zr2F10)$H2O (I) and [Hmeam]2$(Zr2F10)$H2O (II).
Empirical formula Formula weight (g mol1) Crystal system Space group a (Å) b (Å); b ( ) c (Å) V (Å3), Z Four circle diffractometer/ radiation Crystal size (mm3) m(Mo Ka) (mm1) rcalc. (g cm3) Temperature (K) 2q range ( ) (hkl) limits
Rint/Rs Scan mode Absorption correction Tmin, Tmax Reflexions measured/ unique/(I > 2s(I)) Number of refined parameters (on F2) R/Rwa Goodness of fit Weighting scheme (P ¼ [F20 þ 2F2c ]/3) Difference Fourier residues (e Å3) Secondary extinction coefficient
I
II
Zr2F10ON2C3H14 466.59 Triclinic P1(2) 6.805 (1); 94.54(1) 8.361(1); 105.44(1) 11.853 (2); 108.75(1) 605.53(9), 2 Siemens AED2/Mo Ka
Zr2F10ON2C2H14 454.59 Monoclinic C2/m (12) 10.340(6) 6.624(4); 110.57(3) 8.758(6) 561.6(3), 2
0.23 0.07 0.04 1.84 2.559 298 2e55 jhj 8; jkj 10; l 15 0.00/0.049 u 2q Gaussian 0.86, 0.93 2770/2770/2018
0.19 0.12 0.046 1.98 2.688 2e55 13 h 12; 0 k 8; 0 l 11 0.00/0.07
173
57
0.041/0.113 1.074 1/[s2(F20) þ (0.041P)2] þ 4.42 P] 1.023, 1.013
0.057/0.177 1.072 1/[s2(F20) þ (0.106P)2 þ 10P] 1.78, 2.62
5
0.30(9) 10
0.92, 0.98 700/700/540
0.2(2) 10
5
Crystallographic data for the structures have been deposited with the Cambridge Crystallographic Data Center, CCDC Nos 719642 (I), 719643 (II). Copies of data can be obtained, free of charge, on application to the Director, CCDC, 12 Union Road, Cambridge CB2 1EZ, UK (fax: þ44 1223 336033 or e-mail: [email protected]). a R ¼ SjjFobs. Fcalc.jj/SjFobs.j Rw ¼ S[w(jFobs.j2 jFcalc.j2)2/SwjFobs.j4]1/2.
Zr(1)eF(10) Zr(1)eF(4) Zr(1)eF(3) Zr(1)eF(9) Zr(1)eF(2) Zr(1)eF(7) Zr(1)eF(2)
1.942(4) 1.967(4) 1.970(4) 2.131(4) 2.133(4) 2.144(4) 2.149(4)
2.06
Zr(2)eF(8) Zr(2)eF(5) Zr(2)eF(1) Zr(2)eF(6) Zr(2)eF(9) Zr(2)eF(7) Zr(2)eF(6) Zr(2)eF(1)
1.983(4) 1.989(4) 2.101(4) 2.107(4) 2.160(4) 2.162(4) 2.233(4) 2.238(4) 2.12
C(3)eC(1) C(3)eC(2) N(1)eC(2) N(2)eC(1)
1.52(1) 1.52(1) 1.47(1) 1.475(9)
perfectly determined (a ¼ 10.927(3) Å, b ¼ 16.829(4) Å, and c ¼ 10.804(2) Å, b ¼ 112.71(5) , Cc) but the (ZrF7(H2O))3- anions are associated with F anions, diprotonated [H2dap]3þ cations and H2O molecules. At intermediate amine concentrations, two ZrF7 polyhedra, associated by one edge, build Zr2F12 dimers in [H2dap]2$(Zr2F12). The structure of [H2dap]2$(Zr2F12) was previously published [13]. Finally, at low amine concentration, infinite layers of edge sharing polyhedra are evidenced in [H2dap]$(Zr2F10)$ H2O (I). A pure phase of [H2dap]$(Zr2F10)$H2O (I) can be obtained for the following molar composition of the starting ZrF4edapHFeethanol mixture:0.5/0.08/1/17. [Hmeam]2$(Zr2F10)$H2O (II) was prepared from ZrO2, methylamine (95%), HFaq. (40%, Riedel-de Haën). A saturated solution of ZrO2 (2 g) in aqueous HF (20 mL) was first prepared at 60 C and then 0.7 mL of methylamine was added under stirring at room temperature. The resulting solution was left for evaporation at T ¼ 40 C for 12 h and platelet-shape crystals were obtained. A DTA-TGA TA 2960 instrument was used for thermal analyses (heating rate 10 C/min, argon atmosphere) in the temperature range 25e650 C. The solid state NMR experiments were performed with a Bruker Avance 300 spectrometer (7 T) operating at Larmor frequency of 282.2 MHz for 19F nucleus. The 19F spectra were recorded using a CP MAS probe head with a 2.5 mm diameter ZrO2 rotor and employing the Hahn echo sequence in order to avoid baseline distortion. The Hahn echo spectra were acquired in 256 scans using a 2.5 ms 90 pulse and an interpulse delay synchronised with the rotor period. The recycle delay was set to 1 s, and a saturation sequence was implemented. 19F isotropic chemical shifts were referenced to CFCl3. The spectra, recorded at various spinning frequencies, were reconstructed using the DMFit software [14]. 3. Structure determinations of I and II Suitable single crystals of I and II were carefully selected under a polarizing microscope. X-ray diffraction data were collected on a SIEMENS AED2 four-circle diffractometer using u 2q scans with Mo Ka radiation at room temperature. The crystal structures were determined from (hkl) intensities corrected of absorption with SHELX-76 software [15]. Unit cell parameters were refined from least square analysis of 32 reflections in the 2q range 30e32 . Structure solutions were obtained with SHELXS-97 program [16] Table 3 Hydrogen bond distances (Å) in [H2dap]$(Zr2F10)$H2O (I). XeH/F
d(N.F)
OweH(1)/F(5) OweH(2)/F(8) N(1)eH(1)A/Ow N(1)eH(1)C/F(3) N(1)eH(1)B/F(5) N(2)eH(2)B/F(4) N(2)eH(2)A/F(8) N(2)eH(2)C/Ow
2.841(7) 2.813(7) 2.95(1) 2.801(8) 2.92(1) 2.856(8) 2.932(8) 2.91(1)
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A. Ben Ali et al. / Solid State Sciences 13 (2011) 394e398
Table 4 Selected inter-atomic distances (Å) in [Hmeam]2$(Zr2F10)$H2O (II). ZreF(1) ZreF(2) ZreF(4) ZreF(4) ZreF(3) ZreF(3) ZreF(4) ZreF(4)
1.971(8) 2.012(8) 2.072(6) 2.072(6) 2.162(8) 2.177(8) 2.278(5) 2.278(5) 2.13
NeC Ow/Ow Ow/F(2) NeH/F(3)
b
a
c
1.36(4)
Zr(2) F(9)
2.72 2.73
F(1) N(2)
F(10)
Zr(1)
2.79
F(3) F(4)
F(2)
4. Structure descriptions 4.1. Structure of [H2dap]$(Zr2F10)$H2O (I) The structure of I is built up from ZrF7 and ZrF8 polyhedra, 1-3 diaminopropanium cations and water molecules. A projection of the structure on the (a,b) plane is presented in Fig. 2. The average ZreF distances are consistent with the sum of ionic radii for the considered coordination [20]; the longest distances correspond to fluoride anions that connect two Zr4þ cations (Table 2). Zr(2)F8 polyhedra share opposite edges and form infinite Zr(2)F6 chains along the a axis while two Zr(1)F7 polyhedra are associated by only one edge to give Zr2F12 dimers. These Zr(1)2F12 dimers are connected with the Zr(2)F6 chains in order to build infinite N(Zr2F10) layers where ten member cycles of polyhedra leave rectangular windows, z 7 10 Å2 (Fig. 3, left). [H2dap]2þ cations and water molecules are inserted between the Zr2F10 layers; they alternate along the a axis (Fig. 2). Hydrogen
F(5) Ow N(1)
Zr(1) F(8)
F(7)
F(6)
F(8)
F(6) Zr(2)
Zr(2)
F(5)
and refinements were performed with SHELXL-97 program [17] included in WINGX package [18]. The conditions of data collection and crystallographic data are given in Table 1. The structure of I was determined by Patterson method in the P1 space group while the structure of II was determined in the C2/m space group using TREF option of SHELXS-97. Zirconium atoms were first localized. The remaining atoms (oxygen of water molecules, fluoride anions and organic cations), located from Fourier difference maps (SHELX-97), were distinguished from distance criteria [19]. Final refinements of anisotropic displacement parameters (ADP) and secondary extinction converged to R ¼ 0.041 and Rw ¼ 0.113 (2018 independent reflections and 173 parameters) for I, R ¼ 0.057 and Rw ¼ 0.177 (540 independent reflections and 57 parameters) for II. The resulting atomic coordinates with equivalent ADP are given in Supplementary Information; several selected bond distances appear respectively in Tables 2 and 3 for I, in Table 4 for II.
Zr(2)
F(1)
Fig. 3. Projection on the (a,c) plane of a Zr2F10 layer (left) and tetrahedral environment of water molecules (right) of [H2dap]$(Zr2F10)$H2O (I).
c b
F
C N
F(2) F(1)
O
F(3) F(4)
b c
a
Fig. 4. View along [100] (left) and projection of a Zr2F10 layer on the (a,b) plane (right) of [Hmeam]2$(Zr2F10)$H2O (II).
atoms of -NH3 groups and water molecules are involved in hydrogen bonds (Table 3). Water molecules are tetrahedrally surrounded by two fluorine atoms and two NH3 groups (Fig. 3, right). 4.2. Structure of [Hmeam]2$(Zr2F10)$H2O (II) The layered structure of II results from the connection of ZrF8 polyhedra in the (a,b) plane (Fig. 4, left). Every ZrF8 polyhedron shares three edges with three ZrF8 neighbouring polyhedra and strongly distorted hexagonal cycles of polyhedra appear (Fig. 4, right). The ZreF distances, ranging from 1.97 to 2.01 Å for terminal fluorine atoms and from 2.07 to 2.27 Å for bridging F ligands, are very similar to the Zr(2)eF distances found in I. The inorganic layers are separated by disordered methyl ammonium cations and water molecules that form hydrogen bond interactions with terminal fluorine atoms F(2) and F(3) (Table 4). Structure correlations are found between [Hmeam]2$(Zr2F10)$ H2O (II), (H3O)$(ZrF5)$H2O, [H2en]$(Zr2F10)$H2O [5] and (H3O)$ (ZrF5)$2H2O [21]. The inorganic layers are very similar and the interlayer distances vary accordingly with the size of amine cations
N c a b H C
Ow
F
b c
a
a
c
Fig. 2. Projection of the structure of [H2dap]$(Zr2F10)$H2O (I) on the (a,b) plane.
Fig. 5. Projections of (H3O)$(ZrF5)$H2O (left) and (H3O)$(ZrF5)$2H2O (right).
A. Ben Ali et al. / Solid State Sciences 13 (2011) 394e398
397
2
3
5 * * *
*
*
1
4
6
* *
* *
*
* *
*
* (b)
(a) 200
300
100
0
-100
-200
-300
Isotropic chemical shift (ppm) Fig. 6. TGAeDTA analysis of [H2dap]$(Zr2F10)$H2O (I). Fig. 8. Experimental (a) and reconstructed (b) 19F MAS Hahn echo (30 kHz) spectra of [H2dap]$(Zr2F10)$H2O. Stars indicate spinning sidebands. 19F resonances are labelled.
or the number of water molecules: c ¼ 8.758 Å in II, b/2 ¼ 7.806 Å in [H2en]$(Zr2F10)$H2O, c/2 ¼ 9.077 Å in (H3O)$(ZrF5)$2H2O and 8.066 Å in (H3O)$(ZrF5)$H2O. A projection of the structure of (H3O)$ (ZrF5)$H2O along [010] is given in Fig. 5 for comparison with [Hmeam]2$(Zr2F10)$H2O (Fig. 4 left): H3Oþ or water molecules lie between the Zr2F10 layers. 5. Thermal behaviour of I and II The thermal evolutions of I and II exhibit two steps. The first steps correspond to dehydration and lead to [H2dap]$(Zr2F10) and [Hmeam]2$(Zr2F10), respectively. The dehydration starts at T z 100 C (Fig. 6) for I and T z 80 C for II. For I, the first step ends at T z 160 C, the experimental/calculated weight loss is 3.8/ 3.9, while the second step starts at T z 260 C. For II, both events overlap. For I and II, the second steps end at T z 400e430 C with the formation of ZrF4. The total weight loss (exp./calc.) is consistent with this dehydration-decomposition scheme: 27.7/28.3 for I, 26.0/26.4 for II. It must be noted that two thermal events occur between dehydration and decomposition for [H2dap]$(Zr2F10) (I): the first one, at T z 220 C, is exothermic, the second one, at T z 290 C, is endothermic. These features, significant of crystallisation or phase transformation, incited us to study the thermal evolution of I by thermodiffraction (Fig. 7). The results confirm that [H2dap]$(Zr2F10)$H2O (I) disappears above 105 C and that a crystalline phase is then formed. It can be assumed that
a-[H2dap]$(Zr2F10) undergoes two phase transformations to give the b and g varieties; decomposition of this g form starts simultaneously and gives ZrF4. These structural phase transformations, above 175 C and above 245 C, are consistent with the thermal DTA events observed at 220 C and 290 C. For both events, the weight loss is not significant; these transformations are currently investigated. 6.
19
F NMR spectroscopy of [H2dap]$(Zr2F10)$H2O (I)
It can be assumed that the presence of large windows in the layers of [H2dap]$(Zr2F10)$H2O and the good stability of the anhydrous phase obtained on heating induces gas or cation exchange properties in [H2dap]$(Zr2F10)$H2O at the opposite from [Hmeam]2$(Zr2F10)$H2O. As a consequence, a 19F MAS NMR study of [H2dap]$(Zr2F10)$H2O was performed in order to check the absence of OH/F or H2O/HF substitution on fluoride or water sites, respectively, of the structure. The crystallographic structure of [H2dap]$(Zr2F10)$H2O involves ten F sites of equal multiplicity. Consequently, ten NMR lines, with the same relative intensity (10%), are expected. The reconstruction of the 19F MAS NMR spectra recorded at 20, 25 and 30 kHz can be achieved with only six isotropic lines as shown in Fig. 8 for the 30 kHz spectrum; the isotropic chemical shift (diso) values and relative intensities issued from the reconstruction are gathered in Table 5. Two types of environment are distinguished for fluorine atoms in [H2dap]$(Zr2F10)$H2O. For five sites, F1, F2, F6, F7 and F9, the fluorine atoms bridge two Zr atoms. Such a fluoride environment is encountered in b-ZrF4, where all fluorine atoms are coordinated by Table 5 19 F line label, isotropic chemical shift diso, relative line intensity and line assignment for [H2dap]$(Zr2F10)$H2O. Line 1 2 3 4 5 6
Fig. 7. Thermodiffraction of [H2dap]$(Zr2F10)$H2O (I).
diso (ppm)
Relative intensity (%) 1%
Assignment
0.5 ppm 39.7 31.5 28.9 27.2 44.9 78.5
7 23 21 18 21 9
Non bridging F
Bridging F
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A. Ben Ali et al. / Solid State Sciences 13 (2011) 394e398
two zirconium atoms; in this phase, the corresponding experimental diso values range from 9.5 ppm to 30.6 ppm [22]. According to their relative intensities, the lines 4, 5, 6, whose diso values are also positive (27, 45 and 79 ppm respectively), are attributed to 2, 2 and 1 bridging fluorine sites, respectively. The remaining lines, with lower diso values, are assigned to the five other sites, F3, F4, F5, F8 and F10, for which fluorine atoms are linked to one Zr atom only. Their relatives intensities, 1:2:2 are also consistent with the attribution of 1, 2, 2 fluorine sites respectively. Moreover, the experimental overall line intensities of bridging and nonbridging fluorine sites is almost equal. This fair agreement between the experimental and expected line intensities 1/2/2 and 1/2/2 rules out any noticeable substitution of F by OH groups; such a substitution is expected to occur differentially on bridging or nonbridging fluorine sites. As a consequence, the substitution of water molecules by HF species is also excluded. 7. Conclusions Two zirconium fluorides, [H2dap]$(Zr2F10)$H2O and [Hmeam]2$ (Zr2F10)$H2O, are prepared by solvothermal and evaporation routes, respectively. Both structures are built up from N(Zr2F10) layers between which protonated amine cations and water molecules are inserted. The previously unknown Zr2F10 layer of [H2dap]$(Zr2F10)$ H2O leaves open windows delimited by ten polyhedra. Dehydration of both phases is studied. Anhydrous phases appear above T z 100 C. [H2dap]$(Zr2F10) undergoes two phase transformations that are currently investigated. 19F NMR experiments allow the attribution of six isotropic lines to two sets of five fluoride sites in [H2dap]$(Zr2F10)$H2O; they correspond to nonbridging or edge bridging fluoride anions of the ZrF7 or ZrF8 polyhedra. No noticeable OH/F or H2O/HF substitution is evidenced and exchange properties of [H2dap]$(Zr2F10)$H2O can be expected. Acknowledgements Thanks are due to the Région des Pays de la Loire for a postdoctoral grant (A. Ben Ali).
Appendix. Supplementary material Supplementary data related to this article can be found online at doi:10.1016/j.solidstatesciences.2010.11.044.
References [1] R.L. Davidovich, Russ. J. Coord. Chem. 24 (1998) 751. [2] B.V. Bukvetskii, A.V. Gerasimenko, R.L. Davidovich, Koord. Khim. 16 (1990) 1479. [3] C.R. Ross II, M.R. Bauer, R.M. Nielson, S.C. Abrahams, Acta Crystallogr. C60 (2004) m24. [4] C.R. Ross II, B.L. Paulsen, R.M. Nielson, S.C. Abrahams, Acta Crystallogr. B54 (1998) 417. [5] R.E. Sykora, M. Ruf, T.E. Albrecht-Schmitt, J. Solid State Chem. 159 (2001) 198. [6] A.V. Gerasimenko, B.V. Bukvetskii, V.B. Logvinova, R.L. Davidovich, Koord. Khim. 22 (8) (1996) 584. [7] E. Goreshnik, M. Leblanc, V. Maisonneuve, J. Solid State Chem. 177 (2004) 4023. [8] M.A. Saada, A. Hémon-Ribaud, M. Leblanc, V. Maisonneuve, J. Fluorine Chem. 126 (2005) 1072. [9] M.A. Saada, V. Maisonneuve, M. Leblanc, A. Hémon-Ribaud, Solid State Sci. 8 (2006) 104. [10] K. Adil, A. Cadiau, A. Hémon-Ribaud, M. Leblanc, V. Maisonneuve, in: Alain Tressaud (Ed.), Functionalized Inorganic Fluorides: Synthesis, Characterizations & Properties of Nanostructured Solids, Wiley-Blackwell, 2010. [11] K. Adil, M. Leblanc, V. Maisonneuve, P. Lightfoot, Dalton Trans. 39 (2010) 1. [12] K. Adil, A. Le Bail, M. Leblanc, V. Maisonneuve, Inorg. Chem. 49 (2010) 2392. [13] A. Ben Ali, L.S. Smiri, M. Leblanc, V. Maisonneuve, X-Ray Struct. Anal. Online 25 (2009) 37. [14] D. Massiot, F. Fayon, M. Capron, I. King, S. Le Calvez, B. Alonso, J.-O. Durand, B. Bujoli, Z. Gan, G. Hoatson, Magn. Reson. Chem. 40 (2002) 70. [15] G.M. Sheldrick, Shelx-76: a Program for Crystal Structure Determination. Cambridge University, UK, 1976. [16] G.M. Sheldrick, SHELXS-97: a Program for Automatic Solution of Crystal Structures. Göttingen University, Germany, 1997, Release 97e2. [17] G.M. Sheldrick, SHELXL-97: a Program for Crystal Structure Determination. Göttingen University, Germany, 1997. [18] L.J. Farrugia, J. Appl. Crystallogr. 32 (1999) 837. [19] N.E. Brese, M. O’Keeffe, Acta Crystallogr. B47 (1991) 192. [20] R. Shannon, Acta Crystallogr. A32 (1976) 751. [21] P. Charpin, M. Lance, M. Nierlich, J. Lambard, Acta Crystallogr. C44 (1988) 1698. [22] C. Legein, F. Fayon, C. Martineau, M. Body, J.-Y. Buzaré, D. Massiot, E. Durand, A. Tressaud, A. Demourgues, O. Peron, B. Boulard, Inorg. Chem. 45 (2006) 10636.
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Solid State Sciences journal homepage: www.elsevier.com/locate/ssscie
2D zirconium fluorides: Synthesis, structure and NMR spectroscopy A. Ben Ali a, c, *, M. Body b, M. Leblanc a, V. Maisonneuve a a
Laboratoire des Oxydes et Fluorures, UMR 6010 CNRS, Institut de Recherche en Ingénierie Moléculaire et Matériaux Fonctionnels, FR CNRS 2575, Université du Maine, Avenue Olivier Messiaen, 72085 Le MANS Cedex 9, France b Laboratoire de Physique de l’Etat Condensé, UMR 6087 CNRS, Institut de Recherche en Ingénierie Moléculaire et Matériaux Fonctionnels, FR CNRS 2575, Université du Maine, Avenue Olivier Messiaen, 72085 Le MANS Cedex 9, France c Unité de Recherche 99/UR12-30, Faculté des Sciences de Bizerte, 7021 Jarzouna, Tunisia
a r t i c l e i n f o
a b s t r a c t
Article history: Received 11 June 2010 Received in revised form 22 November 2010 Accepted 28 November 2010 Available online 2 December 2010
Two new zirconium (IV) fluorides, [H2dap]$(Zr2F10)$H2O (I) and [Hmeam]2$(Zr2F10)$H2O (II), are synthesized and characterized by X-ray diffraction, thermal techniques and NMR spectroscopy. I is triclinic (P1) with a ¼ 6.805 (1) Å, b ¼ 8.361(1) Å, and c ¼ 11.853 (2) Å, a ¼ 94.54(1) , b ¼ 105.44(1) , g ¼ 108.75(1) . II is monoclinic (C2/m) with a ¼ 10.340(6) Å, b ¼ 6.624(4) Å, c ¼ 8.758(6) Å and b ¼ 110.57 (3) . The structure determinations, performed from single crystal X-ray diffraction data, lead to the R/Rw reliability factors 0.041/0.113 for I and 0.057/0.177 for II. The structures are built up from ZrF7 and ZrF8 units in I and only ZrF8 units in II. The polyhedra share common edges in order to form two different ZrF5 layers that are also found in [H2C2H10N2]$(Zr2F10)$H2O and (H3O)2$(Zr2F10)$H2O. On heating at 145 C, [H2dap]$(Zr2F10)$H2O decomposes to give the anhydrous form [H2dap]$(Zr2F10) that undergoes two successive phase transformations at 220 C and 290 C. 19F NMR spectroscopy confirms the structural features of [H2dap]$(Zr2F10)$H2O (I): two sets of three lines with a relative intensity 1:2:2 are attributed to five bridging fluorine atoms and to five nonbridging fluorine atoms. This spectroscopy demonstrates that a noticeable substitution of F anions by hydroxyl OH groups is excluded, together with the eventual substitution of H2O by HF molecules. Ó 2010 Elsevier Masson SAS. All rights reserved.
Keywords: Fluoride Zirconate Hybrid Microwave heating Solvothermal synthesis Crystal structure Layered structure
1. Introduction High valence metal cations such as Zr4þ or Ta5þ are known to develop different coordination numbers from 6 to 8 and a large variety of geometries from octahedron to dodecahedron, bicapped trigonal prism or square antiprism [1]. In the synthesis of new hybrid compounds, this flexibility is proved to be one of the key parameters that governs the dimensionality of the inorganic sublattice. Hybrid zirconium fluorides illustrate this diversity of polyanion condensation. All dimensionalities are represented. Isolated polyhedra or large polyanions are found in 0D aminoguanidinium zirconates such as [HN4CH6]2$(ZrF6) [2,3] or [H2N4CH6]4$(Zr4F24)$ 4H2O [4] respectively. Only one 2D and one 3D compounds are known: [H2en]$[Zr2F10]$H2O [5] and (H3O)$[Hgua]5$[ZrF5]6 [6]. During the last years, we have investigated the solvothermal synthesis of such hybrid fluorides [7e9] under microwave heating. This technique allows to explore various chemical systems on large concentration domains within a short time and to establish the
crystallisation domains in the composition space. The high dimensionality phases are generally found in HF rich and amine poor compositions of the starting materials [10e12]. Attention has been mainly paid to 3D phases for their potential gas storage applications; however, it can be expected that cation exchange properties can be found in 2D phases. Hereafter, we report on the synthesis, the crystal structures and the thermal behaviour of two new bidimensional zirconium fluorides templated with bis-(1-3-diaminopropane) (dap), [H2dap]$ (Zr2F10)$H2O (I) or methylamine (meam), [Hmeam]2$(Zr2F10)$H2O (II). The ZrF4-dap-HF system is investigated in ethanol solvent under solvothermal conditions at T ¼ 190 C and the syntheses are performed in a microwave oven MDS2100 during 1h. An evaporation technique at room temperature is used for the ZrF4-meam-HF system. The starting Zr/HF molar ratio is fixed at 1/28 while the Zr/ meam ratio varies between 1/2 and 4/1. A pure phase is obtained for Zr/meam ¼ 1/1. 2. Experimental
* Corresponding author. Unité de Recherche 99/UR12-30, Faculté des Sciences de Bizerte, 7021 Jarzouna, Tunisia. Tel.: þ216 97 35 39 70; fax: þ216 72 59 05 66. E-mail address: [email protected] (A. Ben Ali). 1293-2558/$ e see front matter Ó 2010 Elsevier Masson SAS. All rights reserved. doi:10.1016/j.solidstatesciences.2010.11.044
The 2D composition space diagram of the ZrF4-dap-HF system for [Zr4þ] ¼ 0.5 mol L1, is given in Fig. 1. The positions of the points
A. Ben Ali et al. / Solid State Sciences 13 (2011) 394e398
395
Table 2 Selected inter-atomic distances (Å) in [H2dap]$(Zr2F10)$H2O (I).
Fig. 1. Composition space diagram (mol %) of the ZrF4edap-HF system for [Zr4þ] ¼ 0.5 M.
indicate the starting compositions and the labels are associated with the major phases that crystallise. Only three different phases grow and the approximate limits of their domains are indicated in Fig. 1. It is clear that an increase of the HF concentration results in the condensation of the building species and the evolution of the F/ dap ratio in the solids, from 4/1, to 6/1 and then to 10/1, is consistent with the variation of the starting compositions. At high amine concentrations, isolated (ZrF7(H2O))3- entities are observed in [H2dap]2$(ZrF7(H2O))$(F)$3H2O. The structure is not
Table 1 Crystallographic data of [H2dap]$(Zr2F10)$H2O (I) and [Hmeam]2$(Zr2F10)$H2O (II).
Empirical formula Formula weight (g mol1) Crystal system Space group a (Å) b (Å); b ( ) c (Å) V (Å3), Z Four circle diffractometer/ radiation Crystal size (mm3) m(Mo Ka) (mm1) rcalc. (g cm3) Temperature (K) 2q range ( ) (hkl) limits
Rint/Rs Scan mode Absorption correction Tmin, Tmax Reflexions measured/ unique/(I > 2s(I)) Number of refined parameters (on F2) R/Rwa Goodness of fit Weighting scheme (P ¼ [F20 þ 2F2c ]/3) Difference Fourier residues (e Å3) Secondary extinction coefficient
I
II
Zr2F10ON2C3H14 466.59 Triclinic P1(2) 6.805 (1); 94.54(1) 8.361(1); 105.44(1) 11.853 (2); 108.75(1) 605.53(9), 2 Siemens AED2/Mo Ka
Zr2F10ON2C2H14 454.59 Monoclinic C2/m (12) 10.340(6) 6.624(4); 110.57(3) 8.758(6) 561.6(3), 2
0.23 0.07 0.04 1.84 2.559 298 2e55 jhj 8; jkj 10; l 15 0.00/0.049 u 2q Gaussian 0.86, 0.93 2770/2770/2018
0.19 0.12 0.046 1.98 2.688 2e55 13 h 12; 0 k 8; 0 l 11 0.00/0.07
173
57
0.041/0.113 1.074 1/[s2(F20) þ (0.041P)2] þ 4.42 P] 1.023, 1.013
0.057/0.177 1.072 1/[s2(F20) þ (0.106P)2 þ 10P] 1.78, 2.62
5
0.30(9) 10
0.92, 0.98 700/700/540
0.2(2) 10
5
Crystallographic data for the structures have been deposited with the Cambridge Crystallographic Data Center, CCDC Nos 719642 (I), 719643 (II). Copies of data can be obtained, free of charge, on application to the Director, CCDC, 12 Union Road, Cambridge CB2 1EZ, UK (fax: þ44 1223 336033 or e-mail: [email protected]). a R ¼ SjjFobs. Fcalc.jj/SjFobs.j Rw ¼ S[w(jFobs.j2 jFcalc.j2)2/SwjFobs.j4]1/2.
Zr(1)eF(10) Zr(1)eF(4) Zr(1)eF(3) Zr(1)eF(9) Zr(1)eF(2) Zr(1)eF(7) Zr(1)eF(2)
1.942(4) 1.967(4) 1.970(4) 2.131(4) 2.133(4) 2.144(4) 2.149(4)
2.06
Zr(2)eF(8) Zr(2)eF(5) Zr(2)eF(1) Zr(2)eF(6) Zr(2)eF(9) Zr(2)eF(7) Zr(2)eF(6) Zr(2)eF(1)
1.983(4) 1.989(4) 2.101(4) 2.107(4) 2.160(4) 2.162(4) 2.233(4) 2.238(4) 2.12
C(3)eC(1) C(3)eC(2) N(1)eC(2) N(2)eC(1)
1.52(1) 1.52(1) 1.47(1) 1.475(9)
perfectly determined (a ¼ 10.927(3) Å, b ¼ 16.829(4) Å, and c ¼ 10.804(2) Å, b ¼ 112.71(5) , Cc) but the (ZrF7(H2O))3- anions are associated with F anions, diprotonated [H2dap]3þ cations and H2O molecules. At intermediate amine concentrations, two ZrF7 polyhedra, associated by one edge, build Zr2F12 dimers in [H2dap]2$(Zr2F12). The structure of [H2dap]2$(Zr2F12) was previously published [13]. Finally, at low amine concentration, infinite layers of edge sharing polyhedra are evidenced in [H2dap]$(Zr2F10)$ H2O (I). A pure phase of [H2dap]$(Zr2F10)$H2O (I) can be obtained for the following molar composition of the starting ZrF4edapHFeethanol mixture:0.5/0.08/1/17. [Hmeam]2$(Zr2F10)$H2O (II) was prepared from ZrO2, methylamine (95%), HFaq. (40%, Riedel-de Haën). A saturated solution of ZrO2 (2 g) in aqueous HF (20 mL) was first prepared at 60 C and then 0.7 mL of methylamine was added under stirring at room temperature. The resulting solution was left for evaporation at T ¼ 40 C for 12 h and platelet-shape crystals were obtained. A DTA-TGA TA 2960 instrument was used for thermal analyses (heating rate 10 C/min, argon atmosphere) in the temperature range 25e650 C. The solid state NMR experiments were performed with a Bruker Avance 300 spectrometer (7 T) operating at Larmor frequency of 282.2 MHz for 19F nucleus. The 19F spectra were recorded using a CP MAS probe head with a 2.5 mm diameter ZrO2 rotor and employing the Hahn echo sequence in order to avoid baseline distortion. The Hahn echo spectra were acquired in 256 scans using a 2.5 ms 90 pulse and an interpulse delay synchronised with the rotor period. The recycle delay was set to 1 s, and a saturation sequence was implemented. 19F isotropic chemical shifts were referenced to CFCl3. The spectra, recorded at various spinning frequencies, were reconstructed using the DMFit software [14]. 3. Structure determinations of I and II Suitable single crystals of I and II were carefully selected under a polarizing microscope. X-ray diffraction data were collected on a SIEMENS AED2 four-circle diffractometer using u 2q scans with Mo Ka radiation at room temperature. The crystal structures were determined from (hkl) intensities corrected of absorption with SHELX-76 software [15]. Unit cell parameters were refined from least square analysis of 32 reflections in the 2q range 30e32 . Structure solutions were obtained with SHELXS-97 program [16] Table 3 Hydrogen bond distances (Å) in [H2dap]$(Zr2F10)$H2O (I). XeH/F
d(N.F)
OweH(1)/F(5) OweH(2)/F(8) N(1)eH(1)A/Ow N(1)eH(1)C/F(3) N(1)eH(1)B/F(5) N(2)eH(2)B/F(4) N(2)eH(2)A/F(8) N(2)eH(2)C/Ow
2.841(7) 2.813(7) 2.95(1) 2.801(8) 2.92(1) 2.856(8) 2.932(8) 2.91(1)
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Table 4 Selected inter-atomic distances (Å) in [Hmeam]2$(Zr2F10)$H2O (II). ZreF(1) ZreF(2) ZreF(4) ZreF(4) ZreF(3) ZreF(3) ZreF(4) ZreF(4)
1.971(8) 2.012(8) 2.072(6) 2.072(6) 2.162(8) 2.177(8) 2.278(5) 2.278(5) 2.13
NeC Ow/Ow Ow/F(2) NeH/F(3)
b
a
c
1.36(4)
Zr(2) F(9)
2.72 2.73
F(1) N(2)
F(10)
Zr(1)
2.79
F(3) F(4)
F(2)
4. Structure descriptions 4.1. Structure of [H2dap]$(Zr2F10)$H2O (I) The structure of I is built up from ZrF7 and ZrF8 polyhedra, 1-3 diaminopropanium cations and water molecules. A projection of the structure on the (a,b) plane is presented in Fig. 2. The average ZreF distances are consistent with the sum of ionic radii for the considered coordination [20]; the longest distances correspond to fluoride anions that connect two Zr4þ cations (Table 2). Zr(2)F8 polyhedra share opposite edges and form infinite Zr(2)F6 chains along the a axis while two Zr(1)F7 polyhedra are associated by only one edge to give Zr2F12 dimers. These Zr(1)2F12 dimers are connected with the Zr(2)F6 chains in order to build infinite N(Zr2F10) layers where ten member cycles of polyhedra leave rectangular windows, z 7 10 Å2 (Fig. 3, left). [H2dap]2þ cations and water molecules are inserted between the Zr2F10 layers; they alternate along the a axis (Fig. 2). Hydrogen
F(5) Ow N(1)
Zr(1) F(8)
F(7)
F(6)
F(8)
F(6) Zr(2)
Zr(2)
F(5)
and refinements were performed with SHELXL-97 program [17] included in WINGX package [18]. The conditions of data collection and crystallographic data are given in Table 1. The structure of I was determined by Patterson method in the P1 space group while the structure of II was determined in the C2/m space group using TREF option of SHELXS-97. Zirconium atoms were first localized. The remaining atoms (oxygen of water molecules, fluoride anions and organic cations), located from Fourier difference maps (SHELX-97), were distinguished from distance criteria [19]. Final refinements of anisotropic displacement parameters (ADP) and secondary extinction converged to R ¼ 0.041 and Rw ¼ 0.113 (2018 independent reflections and 173 parameters) for I, R ¼ 0.057 and Rw ¼ 0.177 (540 independent reflections and 57 parameters) for II. The resulting atomic coordinates with equivalent ADP are given in Supplementary Information; several selected bond distances appear respectively in Tables 2 and 3 for I, in Table 4 for II.
Zr(2)
F(1)
Fig. 3. Projection on the (a,c) plane of a Zr2F10 layer (left) and tetrahedral environment of water molecules (right) of [H2dap]$(Zr2F10)$H2O (I).
c b
F
C N
F(2) F(1)
O
F(3) F(4)
b c
a
Fig. 4. View along [100] (left) and projection of a Zr2F10 layer on the (a,b) plane (right) of [Hmeam]2$(Zr2F10)$H2O (II).
atoms of -NH3 groups and water molecules are involved in hydrogen bonds (Table 3). Water molecules are tetrahedrally surrounded by two fluorine atoms and two NH3 groups (Fig. 3, right). 4.2. Structure of [Hmeam]2$(Zr2F10)$H2O (II) The layered structure of II results from the connection of ZrF8 polyhedra in the (a,b) plane (Fig. 4, left). Every ZrF8 polyhedron shares three edges with three ZrF8 neighbouring polyhedra and strongly distorted hexagonal cycles of polyhedra appear (Fig. 4, right). The ZreF distances, ranging from 1.97 to 2.01 Å for terminal fluorine atoms and from 2.07 to 2.27 Å for bridging F ligands, are very similar to the Zr(2)eF distances found in I. The inorganic layers are separated by disordered methyl ammonium cations and water molecules that form hydrogen bond interactions with terminal fluorine atoms F(2) and F(3) (Table 4). Structure correlations are found between [Hmeam]2$(Zr2F10)$ H2O (II), (H3O)$(ZrF5)$H2O, [H2en]$(Zr2F10)$H2O [5] and (H3O)$ (ZrF5)$2H2O [21]. The inorganic layers are very similar and the interlayer distances vary accordingly with the size of amine cations
N c a b H C
Ow
F
b c
a
a
c
Fig. 2. Projection of the structure of [H2dap]$(Zr2F10)$H2O (I) on the (a,b) plane.
Fig. 5. Projections of (H3O)$(ZrF5)$H2O (left) and (H3O)$(ZrF5)$2H2O (right).
A. Ben Ali et al. / Solid State Sciences 13 (2011) 394e398
397
2
3
5 * * *
*
*
1
4
6
* *
* *
*
* *
*
* (b)
(a) 200
300
100
0
-100
-200
-300
Isotropic chemical shift (ppm) Fig. 6. TGAeDTA analysis of [H2dap]$(Zr2F10)$H2O (I). Fig. 8. Experimental (a) and reconstructed (b) 19F MAS Hahn echo (30 kHz) spectra of [H2dap]$(Zr2F10)$H2O. Stars indicate spinning sidebands. 19F resonances are labelled.
or the number of water molecules: c ¼ 8.758 Å in II, b/2 ¼ 7.806 Å in [H2en]$(Zr2F10)$H2O, c/2 ¼ 9.077 Å in (H3O)$(ZrF5)$2H2O and 8.066 Å in (H3O)$(ZrF5)$H2O. A projection of the structure of (H3O)$ (ZrF5)$H2O along [010] is given in Fig. 5 for comparison with [Hmeam]2$(Zr2F10)$H2O (Fig. 4 left): H3Oþ or water molecules lie between the Zr2F10 layers. 5. Thermal behaviour of I and II The thermal evolutions of I and II exhibit two steps. The first steps correspond to dehydration and lead to [H2dap]$(Zr2F10) and [Hmeam]2$(Zr2F10), respectively. The dehydration starts at T z 100 C (Fig. 6) for I and T z 80 C for II. For I, the first step ends at T z 160 C, the experimental/calculated weight loss is 3.8/ 3.9, while the second step starts at T z 260 C. For II, both events overlap. For I and II, the second steps end at T z 400e430 C with the formation of ZrF4. The total weight loss (exp./calc.) is consistent with this dehydration-decomposition scheme: 27.7/28.3 for I, 26.0/26.4 for II. It must be noted that two thermal events occur between dehydration and decomposition for [H2dap]$(Zr2F10) (I): the first one, at T z 220 C, is exothermic, the second one, at T z 290 C, is endothermic. These features, significant of crystallisation or phase transformation, incited us to study the thermal evolution of I by thermodiffraction (Fig. 7). The results confirm that [H2dap]$(Zr2F10)$H2O (I) disappears above 105 C and that a crystalline phase is then formed. It can be assumed that
a-[H2dap]$(Zr2F10) undergoes two phase transformations to give the b and g varieties; decomposition of this g form starts simultaneously and gives ZrF4. These structural phase transformations, above 175 C and above 245 C, are consistent with the thermal DTA events observed at 220 C and 290 C. For both events, the weight loss is not significant; these transformations are currently investigated. 6.
19
F NMR spectroscopy of [H2dap]$(Zr2F10)$H2O (I)
It can be assumed that the presence of large windows in the layers of [H2dap]$(Zr2F10)$H2O and the good stability of the anhydrous phase obtained on heating induces gas or cation exchange properties in [H2dap]$(Zr2F10)$H2O at the opposite from [Hmeam]2$(Zr2F10)$H2O. As a consequence, a 19F MAS NMR study of [H2dap]$(Zr2F10)$H2O was performed in order to check the absence of OH/F or H2O/HF substitution on fluoride or water sites, respectively, of the structure. The crystallographic structure of [H2dap]$(Zr2F10)$H2O involves ten F sites of equal multiplicity. Consequently, ten NMR lines, with the same relative intensity (10%), are expected. The reconstruction of the 19F MAS NMR spectra recorded at 20, 25 and 30 kHz can be achieved with only six isotropic lines as shown in Fig. 8 for the 30 kHz spectrum; the isotropic chemical shift (diso) values and relative intensities issued from the reconstruction are gathered in Table 5. Two types of environment are distinguished for fluorine atoms in [H2dap]$(Zr2F10)$H2O. For five sites, F1, F2, F6, F7 and F9, the fluorine atoms bridge two Zr atoms. Such a fluoride environment is encountered in b-ZrF4, where all fluorine atoms are coordinated by Table 5 19 F line label, isotropic chemical shift diso, relative line intensity and line assignment for [H2dap]$(Zr2F10)$H2O. Line 1 2 3 4 5 6
Fig. 7. Thermodiffraction of [H2dap]$(Zr2F10)$H2O (I).
diso (ppm)
Relative intensity (%) 1%
Assignment
0.5 ppm 39.7 31.5 28.9 27.2 44.9 78.5
7 23 21 18 21 9
Non bridging F
Bridging F
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two zirconium atoms; in this phase, the corresponding experimental diso values range from 9.5 ppm to 30.6 ppm [22]. According to their relative intensities, the lines 4, 5, 6, whose diso values are also positive (27, 45 and 79 ppm respectively), are attributed to 2, 2 and 1 bridging fluorine sites, respectively. The remaining lines, with lower diso values, are assigned to the five other sites, F3, F4, F5, F8 and F10, for which fluorine atoms are linked to one Zr atom only. Their relatives intensities, 1:2:2 are also consistent with the attribution of 1, 2, 2 fluorine sites respectively. Moreover, the experimental overall line intensities of bridging and nonbridging fluorine sites is almost equal. This fair agreement between the experimental and expected line intensities 1/2/2 and 1/2/2 rules out any noticeable substitution of F by OH groups; such a substitution is expected to occur differentially on bridging or nonbridging fluorine sites. As a consequence, the substitution of water molecules by HF species is also excluded. 7. Conclusions Two zirconium fluorides, [H2dap]$(Zr2F10)$H2O and [Hmeam]2$ (Zr2F10)$H2O, are prepared by solvothermal and evaporation routes, respectively. Both structures are built up from N(Zr2F10) layers between which protonated amine cations and water molecules are inserted. The previously unknown Zr2F10 layer of [H2dap]$(Zr2F10)$ H2O leaves open windows delimited by ten polyhedra. Dehydration of both phases is studied. Anhydrous phases appear above T z 100 C. [H2dap]$(Zr2F10) undergoes two phase transformations that are currently investigated. 19F NMR experiments allow the attribution of six isotropic lines to two sets of five fluoride sites in [H2dap]$(Zr2F10)$H2O; they correspond to nonbridging or edge bridging fluoride anions of the ZrF7 or ZrF8 polyhedra. No noticeable OH/F or H2O/HF substitution is evidenced and exchange properties of [H2dap]$(Zr2F10)$H2O can be expected. Acknowledgements Thanks are due to the Région des Pays de la Loire for a postdoctoral grant (A. Ben Ali).
Appendix. Supplementary material Supplementary data related to this article can be found online at doi:10.1016/j.solidstatesciences.2010.11.044.
References [1] R.L. Davidovich, Russ. J. Coord. Chem. 24 (1998) 751. [2] B.V. Bukvetskii, A.V. Gerasimenko, R.L. Davidovich, Koord. Khim. 16 (1990) 1479. [3] C.R. Ross II, M.R. Bauer, R.M. Nielson, S.C. Abrahams, Acta Crystallogr. C60 (2004) m24. [4] C.R. Ross II, B.L. Paulsen, R.M. Nielson, S.C. Abrahams, Acta Crystallogr. B54 (1998) 417. [5] R.E. Sykora, M. Ruf, T.E. Albrecht-Schmitt, J. Solid State Chem. 159 (2001) 198. [6] A.V. Gerasimenko, B.V. Bukvetskii, V.B. Logvinova, R.L. Davidovich, Koord. Khim. 22 (8) (1996) 584. [7] E. Goreshnik, M. Leblanc, V. Maisonneuve, J. Solid State Chem. 177 (2004) 4023. [8] M.A. Saada, A. Hémon-Ribaud, M. Leblanc, V. Maisonneuve, J. Fluorine Chem. 126 (2005) 1072. [9] M.A. Saada, V. Maisonneuve, M. Leblanc, A. Hémon-Ribaud, Solid State Sci. 8 (2006) 104. [10] K. Adil, A. Cadiau, A. Hémon-Ribaud, M. Leblanc, V. Maisonneuve, in: Alain Tressaud (Ed.), Functionalized Inorganic Fluorides: Synthesis, Characterizations & Properties of Nanostructured Solids, Wiley-Blackwell, 2010. [11] K. Adil, M. Leblanc, V. Maisonneuve, P. Lightfoot, Dalton Trans. 39 (2010) 1. [12] K. Adil, A. Le Bail, M. Leblanc, V. Maisonneuve, Inorg. Chem. 49 (2010) 2392. [13] A. Ben Ali, L.S. Smiri, M. Leblanc, V. Maisonneuve, X-Ray Struct. Anal. Online 25 (2009) 37. [14] D. Massiot, F. Fayon, M. Capron, I. King, S. Le Calvez, B. Alonso, J.-O. Durand, B. Bujoli, Z. Gan, G. Hoatson, Magn. Reson. Chem. 40 (2002) 70. [15] G.M. Sheldrick, Shelx-76: a Program for Crystal Structure Determination. Cambridge University, UK, 1976. [16] G.M. Sheldrick, SHELXS-97: a Program for Automatic Solution of Crystal Structures. Göttingen University, Germany, 1997, Release 97e2. [17] G.M. Sheldrick, SHELXL-97: a Program for Crystal Structure Determination. Göttingen University, Germany, 1997. [18] L.J. Farrugia, J. Appl. Crystallogr. 32 (1999) 837. [19] N.E. Brese, M. O’Keeffe, Acta Crystallogr. B47 (1991) 192. [20] R. Shannon, Acta Crystallogr. A32 (1976) 751. [21] P. Charpin, M. Lance, M. Nierlich, J. Lambard, Acta Crystallogr. C44 (1988) 1698. [22] C. Legein, F. Fayon, C. Martineau, M. Body, J.-Y. Buzaré, D. Massiot, E. Durand, A. Tressaud, A. Demourgues, O. Peron, B. Boulard, Inorg. Chem. 45 (2006) 10636.