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Syntheses, crystal structures and thermoanalyses of thiostannates [Ni(en)3]2Sn2S6 and [Ni(dien)2]2Sn2S6
Polyhedron 23 (2004) 937–942 www.elsevier.com/locate/poly
Syntheses, crystal structures and thermoanalyses of thiostannates [Ni(en)3]2Sn2S6 and [Ni(dien)2]2Sn2S6 Ding-Xian Jia a, Jie Dai a
a,b,*
, Qin-Yu Zhu a, Yong Zhang a, Xiao-Mei Gu
a
Department of Chemistry and Chemical Engineering, Suzhou University, Suzhou 215006, PR China State Key Laboratory of Coordination Chemistry, Nanjing University, Nanjing 210093 PR China
b
Received 19 August 2003; accepted 26 November 2003
Abstract Two thiostannates [Ni(en)3 ]2 Sn2 S6 (1) (en ¼ ethylenediamine) and [Ni(dien)2 ]2 Sn2 S6 (2) (dien ¼ diethylenetriamine) were prepared by the reaction of SnCl4 5H2 O, NiCl2 6H2 O and S8 in a molar ratio of Sn/Ni/S ¼ 1:1:4 (or SnCl4 :NiCl2 :S8 ¼ 1:1:0.5) under solvothermal conditions. Both compounds are composed of the discrete [Sn2 S6 ]4 anion. The coordinated cations [Ni(en)3 ]2þ and [Ni(dien)2 ]2þ act as structure directing agents which lead to different packing of the [Sn2 S6 ]4 anions. Compounds 1 and 2 decompose at 291 and 310 C, respectively, and both of them lose all of their organic ligands in one step under a nitrogen stream. The hydrogen bonds are considered to be one of the important reasons for their difference in decomposition temperature. 2003 Elsevier Ltd. All rights reserved. Keywords: Solvothermal synthesis; Thiostannates; Nickel; Crystal structures; Thermoanalysis
1. Introduction Open framework materials based on main group chalcogenometalates are of increasing interest because of their unique properties and potential applications, such as semiconductors [1–3], photoconductivity [4], non-linear optics [5], catalysis [6] and ion exchange capability [7]. Recently, two types of polythiostannates [Sn3 S7 ]2 [7–11] and [Sn4 S9 ]2 [11–14], which are denoted SnS-1 and SnS-3, respectively, have been synthesized and described. SnS-1 and SnS-3 are synthesized by a hydrothermal reaction using Sn or SnS2 and S8 as reactants and amine or tetra-alkylammonium hydroxide as the mineralizer. The dimeric anion [Sn2 S6 ]4 is a precursor of SnS-1 which can be obtained from an aqueous solution of [Sn2 S6 ]4 simply by precise control of pH through bubbling CO2 into the motherliquor [9,11]. The dimeric anion is the predominant tin-containing species in the synthetic systems of Sn/S/
*
Corresponding author. Tel./fax: +86-512-65224783. E-mail address: [email protected] (J. Dai).
0277-5387/$ - see front matter 2003 Elsevier Ltd. All rights reserved. doi:10.1016/j.poly.2003.12.008
amine and a basic building block for the SnS-n framework [11]. In most of the thiostannates compounds, the cations, which compensate the anions charge in the structure, are either protonated amine or tetra-alkylammonium [7–13] ions or metal cations [14,15]. Thiostannates which combine with transition metal complex cations as counterions are still a less explored area [16]. The transition metal complex cations may serve as structuredirecting agents in growing chalcogenometalates crystals [17]. Bensch et al. [18] very recently reported four compounds of this kind with [Sn2 S6 ]4 anions, using elemental nickel, tin and sulphur as starting reactants. In this work, we have successfully prepared thiostannates [Ni(en)3 ]2 Sn2 S6 and [Ni(dien)2 ]2 Sn2 S6 from the Ni(II)/Sn(IV)/S/en (or dien) (en ¼ ethylenediamine, dien ¼ diethylenetriamine) system under mild solvothermal conditions. This combination of transition metal ions may endue thiostannates with new properties that the transition metals have. The structures of compounds [Ni(en)3 ]2 Sn2 S6 and [Ni(dien)2 ]2 Sn2 S6 are described and their thermal behaviors have been investigated.
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D.-X. Jia et al. / Polyhedron 23 (2004) 937–942
2. Experimental 2.1. Synthesis of [Ni(en)3 ]2 Sn2 S6 (1) The source materials of NiCl2 6H2 O (0.7131 g, 3 mmol), SnCl4 5H2 O (1.052 g, 3 mmol) and S8 (0.3848 g, 1.5 mmol) dissolved in 10 ml en and were carefully mixed, and then loaded into a Teflon-lined stainless steel autoclave whose volume was about 15 ml. Then the sealed autoclave was heated to 180 C over 4 h and maintained at this temperature for four days. After cooling to room temperature, purple cubic crystals were isolated and washed with ethanol and ether (yield 65%, based on Sn). IR (cm1 ): 3221vs, 3121vs, 2920m, 2870m, 1671w, 1578m, 1451m, 1385m, 1323m, 1281m, 1273m, 1092m, 1011vs, 864m, 675s, 525m, 486m. Elemental analysis Found: C, 15.64; H, 5.38; N, 18.42%. C12 H48 Ni2 N12 Sn2 S6 requires: C, 15.88; H, 5.33; N, 18.52%. 2.2. Synthesis of [Ni(dien)2 ]2 Sn2 S6 (2) The pink prism-like crystals of [Ni(dien)2 ]2 Sn2 S6 were prepared by a similar method used in the synthesis of the crystals of 1 except that ethylenediamine was replaced by diethylenetriamine (yield 65%, based on Sn). IR (cm1 ): 3237m, 3133m, 2967w, 2863w, 1621m, 1574m, 1470s, 1385m, 1323m, 1281m, 1238m, 1181m, 1080vs, 1042m, 995m, 961vs, 860m, 783m, 675m, 633m, 598s, 532s. Elemental analysis Found: C, 20.08; H, 5.62; N, 17.46%. C16 H52 Ni2 N12 Sn2 S6 requires: C, 20.02; H, 5.46; N, 17.51%. 2.3. Physical measurements FT-IR spectra were recorded with a Nicolet MagnaIR 550 spectrometer in dry KBr pellets. Elemental analysis was carried out on an EA-1110 elemental analyzer. Thermogravimetric (TG) analysis was conducted on a SDT 2960 TGA-DCS microanalyzer. All the samples were heated under a nitrogen stream of 100 ml/ min with a heating rate of 5 C/min.
Table 1 Crystallographic data for [Ni(en)3 ]2 Sn2 S6 (1) and [Ni(dien)2 ]2 Sn2 S6 (2) Compound
1
2
Empirical formula Fw Crystal size (mm) Colour, habit Crystal system Space group a (A) b (A) c (A)
C12 H48 Ni2 N12 Sn2 S6 907.73 0.50 · 0.45 · 0.40 purple, cubic orthorhombic Pbca (No. 61) 11.5212(8) 18.631(2) 15.2368(11) 90.00 3270.5(4) 4 193 1.843 30.52 55.0 31,956 3499 0.044 3134 (I > 3rðIÞ) 208 0.036 (I > 3rðIÞ) 0.129 1.058
C16 H52 Ni2 N12 Sn2 S6 959.81 0.30 · 0.15 · 0.12 pink, prism monoclinic P 21 =n (No. 14) 9.9168(10) 14.392(1) 12.0589(11) 91.906(5) 1720.1(3) 2 193 1.853 29.07 55.0 17,214 3922 0.029 3588 (I > 2rðIÞ) 202 0.022 (I > 2rðIÞ) 0.047 0.99
b () 3 ) V (A Z T (K) Dcalc: (g cm3 ) l (cm1 ) 2h(max) () Reflections collected Unique reflections Rint Observations Variables R1 wR2 (for all reflections) Goodness of fit indicator
DI R D I F program system). Both of the structures were expanded using Fourier techniques DI R D I F 99. The non-hydrogen atoms were refined anisotropically. Hydrogen atoms were refined using the riding model for compound 2, while the hydrogen atoms of 1 were not dealt with due to the disorder of en. The final cycle of full-matrix least-squares refinement on F 2 was based on definite observed reflections and variable parameters, and converged with unweighted and weighted agreement factors of R1 and wR2 . A summary of the experimental details and selected results for compounds 1 and 2 is given in Table 1.
3. Results and discussion
2.4. Single crystal structure determination
3.1. Synthesis of the compounds
The measurement was carried out on a Rigaku Mercury CCD diffractometer using the x-scan method with graphite monochromated Mo Ka radiation (k ¼ 0:07107 nm) at )80 1 C. The X-ray diffraction data of single crystals were collected to a maximum 2h value of 55.0 for both 1 and 2. An empirical absorption correction was applied for all compounds and the data were corrected for Lorentz and polarization effects. The structure of 1 was solved by direct methods using the program of SH E L X 97 and the structure of 2 was solved by heavy-atom Patterson methods using PATTM (the
Single crystals of [Ni(en)3 ]2 Sn2 S6 (1) and [Ni(dien)2 ]2 Sn2 S6 (2) are obtained by using the reaction of SnCl4 5H2 O, NiCl2 6H2 O and S8 in the same molar ratio of Sn/Ni/S ¼ 1:1:4 (SnCl4 :NiCl2 :S8 ¼ 1:1:0.5) under mild solvothermal conditions in en and dien solvent, respectively. Stannic chloride was used as the source material instead of Sn powder which is usually used in synthesis of thiostannates under hydrothermal or solvothermal conditions [9,10,18]. The Ozin group had studied the Sn/S/amine (water solution) system in detail and isolated dimeric [Sn2 S6 ]4 and [S2 O3 ]2 reaction in-
D.-X. Jia et al. / Polyhedron 23 (2004) 937–942
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termediates from the solution [11]. The redox disproportionation reaction of S8 is believed to be one of the sources of the S2 ion (as Eq. (1) [19]) which is used to form the [Sn2 S6 ]4 anion. þ 1=2S8 þ 9H2 O ! 2S2 þ S2 O2 3 þ 6H3 O
ð1Þ
In the case of the Sn4þ /S/en (dien) system in this work, the S2 ions which are necessary to form [Sn2 S6 ]4 might also come from disproportionation of S8 as Eq. (1), since the metal salts used are hydrated and the solvents are also not absolutely anhydrous. On the other hand, the ethylenediamine in this system might not only act as a solvent, but also offer a source of S2 (or S2 m ) by reacting with elemental sulphur: S þ en ! S2 ðor S2 m Þ þ ðHenÞ
þ
þ oxidized product of amine
ð2Þ
Reaction (2) is complicated and has not been studied in detail. When the sulphur reacts with en, a dark brown color is developed immediately and the species of S2 , þ S2 m and (Hen) have been confirmed by the products, such as (enH)4 [Sn2 S6 ], (enH)4 [Sn2 Se6 ] en, (enH)4 [Sn2 Te6 ] en [20] and [Mn(en)3 ]Te4 [21]. However, the mechanism of the synthetic reaction needs to be further confirmed. It is noteworthy that transition metal cations [Ni(en)3 ]2þ and [Ni(dien)2 ]2þ are likely better mineralizers than the protonated amines such as enHþ and dienHþ , because the products from the Ni2þ /Sn4þ /S/en (dien) system are [Ni(en)3 ]2 Sn2 S6 and [Ni(dien)2 ]2 Sn2 S6 rather than (enH)4 Sn2 S6 and (dienH)4 Sn2 S6 . If the nickel salts were not introduced into these systems under the same experimental conditions, crystallization of (enH)4 [Sn2 S6 ] is very difficult and the crystals were only obtained after the reaction solution had been left for about one month at room temperature.
Fig. 1. The structures of the transition metal complex cations in 1 (a) and 2 (b) with the labelling scheme and ellipsoids at 50% probability. Hydrogen atoms have been omitted for clarity.
3.2. Description of the structures The crystal structures of compounds 1 and 2 were determined by the single-crystal X-ray diffraction method. The results show that compound 1 crystallizes in the orthorhombic space group of Pbca (No. 61) and compound 2 in the monoclinic space group of P 21 =n (No. 14). Both compounds consist of discrete [Sn2 S6 ]4 anions with [Ni(en)3 ]2þ or [Ni(dien)2 ]2þ cations as counterions. The structure of compound 1 is essentially the same as that of [Ni(en)3 ]2 Sn2 S6 which was very recently synthesized by the Bensch group, but they use elemental nickel, tin and sulphur as starting reactants [18]. The Ni2þ ion is coordinated by six N atoms of three bidentate ethylenediamine ligands with Ni–N distances ranging The conformation of from 2.097(4) to 2.146(5) A. [Ni(en)3 ]2þ cation is difficult to fix due to the disorder of the ethylenediamine ligands. The configurations of the ligands are disordered with K ðdddÞ:D ðkkkÞ [or D ðkkkÞ :K ðdddÞ in inversion position] occupation ratios of 0.76:0.24 (Fig. 1(a)). In compound 2, the Ni2þ ion is coordinated by six N atoms of two trichelating dieth-
Table 2 and angles () for [Ni(en)3 ]2 Sn2 S6 (1) and [Ni(dien)2 ]2 Sn2 S6 (2) Selected bond distances (A) 1
2
1
2
Bond distances Ni–N1 Ni–N2 Ni–N3
2.108(4) 2.133(4) 2.137(4)
2.118(2) 2.143(2) 2.090(2)
Ni–N4 Ni–N5 Ni–N6
2.097(4) 2.116(4) 2.146(5)
2.133(2) 2.113(2) 2.102(2)
Sn–S1 Sn–S2
2.338(1) 2.347(1)
2.354(1) 2.334(1)
Sn–S3 Sn–S30
2.453(1) 2.457(1)
2.461(1) 2.453(1)
Bond angles (1) N–Ni–Ntrans: (3) N–Ni–Ntrans:
172.3(2) 169.7(2)
179.47(7) 177.56(7)
(2) N–Ni–Ntrans:
172.3(2)
177.52(8)
S1–Sn–S2 S1–Sn–S3 S2–Sn–S3 S1–Sn–S30
111.52(4) 114.58(4) 112.40(3) 112.20(3)
114.48(2) 113.24(2) 111.53(2) 110.59(2)
S2–Sn–S30 S3–Sn–S30 Sn–S3–Sn0
113.18(3) 91.61(4) 88.39(4)
112.07(2) 93.013(19) 86.987(19)
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Fig. 2. The structure of the [Sn2 S6 ]4 anion with the labelling scheme and ellipsoids at 50% probability.
[Sn2 S6 ]4 anion is surrounded by four [Ni(en)3 ]2þ cations in 1, and by six [Ni(dien)2 ]2þ cations in 2. Between the anion and cation in compound 2, a lot of short intermolecular N–H S interactions, which indicate weak hydrogen bonding, are found and one Sn2 S6 unit is hydrogen bonded to six different cations (Fig. 4(b)). The terminal S(1) and S(2) atoms form hydrogen bonds to H–N groups of [Ni(dien)2 ]2þ cations with H S distances ranging from 2.508(3) to 2.888(2) and N–H S angles ranging from 145.0(2) to A
ylenetriamine ligands. The conformation of octahedral [Ni(dien)2 ]2þ is s-facial (Fig. 1(b)). In compounds 1 and 2, The Ni–N bond lengths are within the range for compounds containing [Ni(en)3 ]2þ and [Ni(dien)2 ]2þ cations [22,23]. The [Ni(en)3 ]2þ and [Ni(dien)2 ]2þ octahedral coordination spheres are distorted, which can be seen from the N–Ni–Ntrans angles varying from 169.7(2) to 172.3(2) and 177.52(8) to 179.47(7), respectively. The three octahedral axial N– Ni–Ntrans angles of the coordination octahedra are listed in Table 2. The [Sn2 S6 ]4 anion, which is formed by the connection of two SnS4 tetrahedra sharing a common edge, can be described as a planar Sn2 S2 four-membered ring with each Sn atom having two terminal Sn–S bonds (Fig. 2). The terminal Sn–St bond lengths, being be are shorter than those of tween 2.334(1) and 2.354(1) A, the bridging Sn–Sb bonds which vary from 2.461(1) to Both kinds of bond lengths are in good 2.453(1) A. agreement with corresponding bond lengths in other compounds containing [Sn2 S6 ]4 anions [20,24]. The two SnS4 tetrahedra in the [Sn2 S6 ]4 dimer are slightly distorted, which is demonstrated by the St –Sn–St and St –Sn–Sb angles deviating from the ideal value of 109.5 (Table 2). The packing of [Sn2 S6 ]4 anions in compounds 1 and 2 is different (shown in Fig. 3). There are eight [Sn2 S6 ]4 anions at corners and six at crystal faces per unit cell of 1, while there are four [Sn2 S6 ]4 anions at crystal edges and two at crystal faces of [0 0 1] per unit cell of 2. One
Fig. 4. The views of the [Sn2 S6 ]4 anion hydrogen bonding interaction with cations in 1 (a) and 2 (b). Hydrogen atoms have been omitted for clarity.
Fig. 3. The packing of the [Sn2 S6 ]4 anions in 1 (a) and 2 (b), the cations have been omitted for clarity.
D.-X. Jia et al. / Polyhedron 23 (2004) 937–942 Table 3 Selected H S distances [Ni(dien)2 ]2 Sn2 S6
(A)
and
N–H S
angles
()
in
N–H
S
N–H
H S
N S
N–H S
N(1)–H(1) N(2)–H(4) N(4)–H(15) N(5)–H(17) N(6)–H(18) N(1)–H(2) N(3)–H(5) N(4)–H(14) N(5)–H(16)
S(1) S(1) S(1) S(1) S(1) S(2) S(2) S(2) S(2)
0.761(3) 0.875(4) 0.897(3) 0.885(3) 0.900(3) 0.915(3) 0.924(3) 0.942(3) 0.906(3)
2.812(2) 2.888(2) 2.571(2) 2.583(2) 2.527(2) 2.582(2) 2.705(2) 2.508(2) 2.846(2)
3.484(2) 3.639 3.453(2) 3.461(2) 3.394(2) 3.419(2) 3.561(2) 3.407(2) 3.676
148.5(2) 145.0(2) 168.2(2) 171.7(2) 161.6(2) 152.2(2) 154.5(2) 159.7(2) 153.0(2)
171.7(2) (Table 3). In compound 1, the number of interion interactions is less than that in 2 (Fig. 4(a)) and this difference might be the reason of disorder of the ethylenediamine in 1. The results show that [Ni(en)3 ]2þ and [Ni(dien)2 ]2þ cations have different structure-directing
941
effects, although both of them are actually synthesized under the same conditions except for the amine. 3.3. Thermal analysis The thermal behavior of the title compounds were measured between temperatures of 20 and 600 C with the DSC-TGA method under nitrogen. The results are shown in Fig. 5. The first step mass loss of 1 (about 0.56% below 100 C) is attributed to desorption of water (Fig. 5(a)). Compound 1 is decomposed at 291 C accompanied by one endothermic peak in the DSC curve (peak temperature, Tp ). The corresponding loss of 40.8% is in accordance with the complete mass loss of six en ligands (Calc. 39.7% for 6 en). The decomposition of 2 is at 310 C (Tp of DSC) and the corresponding loss of 42.2% is in good agreement with the complete mass loss of the four dien ligands (Calc. 43.0% for 4 dien). From the behaviors of thermal decomposition, it is obvious that compounds 1 and 2 remove all of their organic amine ligands in one step under nitrogen. The decomposition temperature of 2 is higher than that of 1 by about 20 C. This result can be explained reasonably by the structure analysis that shows compound 2 has more N–H S hydrogen bonds than compound 1, which makes the organic ligands in 2 more difficult to remove.
4. Conclusions Single crystals of [Ni(en)3 ]2 Sn2 S6 and [Ni(dien)2 ]2 Sn2 S6 can be obtained by reaction of SnCl4 5H2 O, NiCl2 6H2 O and S8 under mild solvothermal conditions. The results presented in this paper demonstrate that the transition metal complex cations can act as a mineralizer in the synthesis of [Sn2 S6 ]4 thiostannates from the Ni(II)/Sn(IV)/S/en (dien) system using solvothermal techniques. The [Ni(en)3 ]2þ and [Ni(dien)2 ]2þ cations are likely a better mineralizer than protonated amines, such as enHþ and dienHþ . The different structure directing effect of [Ni(en)3 ]2þ and [Ni(dien)2 ]2þ cations is one of the reasons that [Sn2 S6 ]4 anions arrange in a different way in the crystal structures of compounds 1 and 2. Both title compounds lose all of their amine ligands in one step under nitrogen. The decomposition temperature of 2 is higher than that of 1 by about 20 C, accounting for the N–H S hydrogen bonding.
5. Supplementary data
Fig. 5. Thermogravimetric analyses curves of compounds 1 (a) and 2 (b).
Crystallographic data for the structural analyses have been deposited with the Cambridge Crystallographic Data Centre, CCDC nos. 217522 and 217523 for com-
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pounds 1 and 2, respectively. These data can be obtained free of charge via www.ccdc.cam.ac.uk/conts/retrieving.html or from the Cambridge Crystallographic Data Centre, 12 Union Road, Cambridge CB2 1EZ, UK; fax: (+44) 1223-336-033, or e-mail: [email protected].
Acknowledgements This work was supported by the National Natural Science Foundation (20071024, 20371033), P.R. China. The authors are also grateful to the Key Laboratory of Organic Synthesis of Jiangsu Province, Suzhou University, for financial support. References [1] C.L. Bowes, G.A. Ozin, Adv. Mater. 8 (1996) 13. [2] J. Llanos, C. Mujica, V. Sanchez, O. Pe~ na, J. Solid State Chem. 173 (2003) 78. [3] C.R. Evenson IV, P.K. Dorhout, Z. Anorg. Allg. Chem. 627 (2001) 2178. [4] U. Simon, F. Sch€ uth, S. Schunk, X. Wang, F. Liebau, Angew. Chem. Int. Ed. Engl. 36 (1977) 1121. [5] R.L. Glitzendanner, F.L. Di Salvo, Inorg. Chem. 35 (1996) 2623. [6] R.R. Chianelli, T.A. Pecoraro, T.R. Halber, W.-H. Pan, E.I. Stiefel, J. Catal. 86 (1984) 226.
[7] J.B. Parise, Y. Ko, J. Rijssenbeek, D.M. Nellis, K. Tan, S. Koch, J. Chem. Soc. Chem. Commun. (1994) 527. [8] J. Li, H. Kessler, Micropor. Mesopor. Mater. 27 (1999) 57. [9] T. Jiang, A. Lough, G.A. Ozin, Adv. Mater. 10 (1998) 42. € Dag, S. Petrov, G.A. Ozin, J. Phys. Chem. B 102 [10] H. Ahari, O. (1998) 2356. [11] T. Jiang, A. Lough, G.A. Ozin, R.L. Bedard, J. Mater. Chem. 8 (1998) 733. [12] T. Jiang, A. Lough, G.A. Ozin, R.L. Bedard, R. Broach, J. Mater. Chem. 8 (1998) 721. [13] Y. Ko, K. Tan, D.M. Nellis, S. Koch, J.B. Parise, J. Solid State Chem. 114 (1995) 506. [14] G.A. Marking, M. Evain, V. Petricek, M.G. Kanatzidis, J. Solid State Chem. 141 (1998) 17. [15] J. Liao, C. Varotsis, M.G. Kanatzidis, Inorg. Chem. 32 (1993) 2453. [16] J. Li, Z. Chen, R.J. Wang, D.M. Proserpio, Coord. Chem. Rev. 190–192 (1999) 707. [17] R. St€ahler, W. Bensch, Eur. J. Inorg. Chem. 12 (2001) 3073. [18] M. Behrens, S. Scherb, C. N€ather, W. Bensch, Z. Anorg. Allg. Chem. 629 (2003) 1367. [19] W.F. Gigenbach, Inorg. Chem. 13 (1974) 1724. [20] S. Dehnen, C. Zimmermann, Z. Anorg. Allg. Chem. 628 (2002) 2463. [21] Z. Chen, R.-J. Wang, X.-Y. Huang, J. Li, Acta Crystallogr. Section C 56 (2000) 1100. [22] M. Ohba, N. Maruono, H. kawa, T. Enoki, J.-M. Latour, J. Am. Chem. Soc. 116 (1994) 11566. [23] W. Bensch, C. N€ather, R. St€ahler, Chem. Commun. (2001) 477. [24] J. Li, B. Marler, H. Kessler, M. Soulard, S. Kallus, Inorg. Chem. 36 (1997) 4697.
Syntheses, crystal structures and thermoanalyses of thiostannates [Ni(en)3]2Sn2S6 and [Ni(dien)2]2Sn2S6 Ding-Xian Jia a, Jie Dai a
a,b,*
, Qin-Yu Zhu a, Yong Zhang a, Xiao-Mei Gu
a
Department of Chemistry and Chemical Engineering, Suzhou University, Suzhou 215006, PR China State Key Laboratory of Coordination Chemistry, Nanjing University, Nanjing 210093 PR China
b
Received 19 August 2003; accepted 26 November 2003
Abstract Two thiostannates [Ni(en)3 ]2 Sn2 S6 (1) (en ¼ ethylenediamine) and [Ni(dien)2 ]2 Sn2 S6 (2) (dien ¼ diethylenetriamine) were prepared by the reaction of SnCl4 5H2 O, NiCl2 6H2 O and S8 in a molar ratio of Sn/Ni/S ¼ 1:1:4 (or SnCl4 :NiCl2 :S8 ¼ 1:1:0.5) under solvothermal conditions. Both compounds are composed of the discrete [Sn2 S6 ]4 anion. The coordinated cations [Ni(en)3 ]2þ and [Ni(dien)2 ]2þ act as structure directing agents which lead to different packing of the [Sn2 S6 ]4 anions. Compounds 1 and 2 decompose at 291 and 310 C, respectively, and both of them lose all of their organic ligands in one step under a nitrogen stream. The hydrogen bonds are considered to be one of the important reasons for their difference in decomposition temperature. 2003 Elsevier Ltd. All rights reserved. Keywords: Solvothermal synthesis; Thiostannates; Nickel; Crystal structures; Thermoanalysis
1. Introduction Open framework materials based on main group chalcogenometalates are of increasing interest because of their unique properties and potential applications, such as semiconductors [1–3], photoconductivity [4], non-linear optics [5], catalysis [6] and ion exchange capability [7]. Recently, two types of polythiostannates [Sn3 S7 ]2 [7–11] and [Sn4 S9 ]2 [11–14], which are denoted SnS-1 and SnS-3, respectively, have been synthesized and described. SnS-1 and SnS-3 are synthesized by a hydrothermal reaction using Sn or SnS2 and S8 as reactants and amine or tetra-alkylammonium hydroxide as the mineralizer. The dimeric anion [Sn2 S6 ]4 is a precursor of SnS-1 which can be obtained from an aqueous solution of [Sn2 S6 ]4 simply by precise control of pH through bubbling CO2 into the motherliquor [9,11]. The dimeric anion is the predominant tin-containing species in the synthetic systems of Sn/S/
*
Corresponding author. Tel./fax: +86-512-65224783. E-mail address: [email protected] (J. Dai).
0277-5387/$ - see front matter 2003 Elsevier Ltd. All rights reserved. doi:10.1016/j.poly.2003.12.008
amine and a basic building block for the SnS-n framework [11]. In most of the thiostannates compounds, the cations, which compensate the anions charge in the structure, are either protonated amine or tetra-alkylammonium [7–13] ions or metal cations [14,15]. Thiostannates which combine with transition metal complex cations as counterions are still a less explored area [16]. The transition metal complex cations may serve as structuredirecting agents in growing chalcogenometalates crystals [17]. Bensch et al. [18] very recently reported four compounds of this kind with [Sn2 S6 ]4 anions, using elemental nickel, tin and sulphur as starting reactants. In this work, we have successfully prepared thiostannates [Ni(en)3 ]2 Sn2 S6 and [Ni(dien)2 ]2 Sn2 S6 from the Ni(II)/Sn(IV)/S/en (or dien) (en ¼ ethylenediamine, dien ¼ diethylenetriamine) system under mild solvothermal conditions. This combination of transition metal ions may endue thiostannates with new properties that the transition metals have. The structures of compounds [Ni(en)3 ]2 Sn2 S6 and [Ni(dien)2 ]2 Sn2 S6 are described and their thermal behaviors have been investigated.
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2. Experimental 2.1. Synthesis of [Ni(en)3 ]2 Sn2 S6 (1) The source materials of NiCl2 6H2 O (0.7131 g, 3 mmol), SnCl4 5H2 O (1.052 g, 3 mmol) and S8 (0.3848 g, 1.5 mmol) dissolved in 10 ml en and were carefully mixed, and then loaded into a Teflon-lined stainless steel autoclave whose volume was about 15 ml. Then the sealed autoclave was heated to 180 C over 4 h and maintained at this temperature for four days. After cooling to room temperature, purple cubic crystals were isolated and washed with ethanol and ether (yield 65%, based on Sn). IR (cm1 ): 3221vs, 3121vs, 2920m, 2870m, 1671w, 1578m, 1451m, 1385m, 1323m, 1281m, 1273m, 1092m, 1011vs, 864m, 675s, 525m, 486m. Elemental analysis Found: C, 15.64; H, 5.38; N, 18.42%. C12 H48 Ni2 N12 Sn2 S6 requires: C, 15.88; H, 5.33; N, 18.52%. 2.2. Synthesis of [Ni(dien)2 ]2 Sn2 S6 (2) The pink prism-like crystals of [Ni(dien)2 ]2 Sn2 S6 were prepared by a similar method used in the synthesis of the crystals of 1 except that ethylenediamine was replaced by diethylenetriamine (yield 65%, based on Sn). IR (cm1 ): 3237m, 3133m, 2967w, 2863w, 1621m, 1574m, 1470s, 1385m, 1323m, 1281m, 1238m, 1181m, 1080vs, 1042m, 995m, 961vs, 860m, 783m, 675m, 633m, 598s, 532s. Elemental analysis Found: C, 20.08; H, 5.62; N, 17.46%. C16 H52 Ni2 N12 Sn2 S6 requires: C, 20.02; H, 5.46; N, 17.51%. 2.3. Physical measurements FT-IR spectra were recorded with a Nicolet MagnaIR 550 spectrometer in dry KBr pellets. Elemental analysis was carried out on an EA-1110 elemental analyzer. Thermogravimetric (TG) analysis was conducted on a SDT 2960 TGA-DCS microanalyzer. All the samples were heated under a nitrogen stream of 100 ml/ min with a heating rate of 5 C/min.
Table 1 Crystallographic data for [Ni(en)3 ]2 Sn2 S6 (1) and [Ni(dien)2 ]2 Sn2 S6 (2) Compound
1
2
Empirical formula Fw Crystal size (mm) Colour, habit Crystal system Space group a (A) b (A) c (A)
C12 H48 Ni2 N12 Sn2 S6 907.73 0.50 · 0.45 · 0.40 purple, cubic orthorhombic Pbca (No. 61) 11.5212(8) 18.631(2) 15.2368(11) 90.00 3270.5(4) 4 193 1.843 30.52 55.0 31,956 3499 0.044 3134 (I > 3rðIÞ) 208 0.036 (I > 3rðIÞ) 0.129 1.058
C16 H52 Ni2 N12 Sn2 S6 959.81 0.30 · 0.15 · 0.12 pink, prism monoclinic P 21 =n (No. 14) 9.9168(10) 14.392(1) 12.0589(11) 91.906(5) 1720.1(3) 2 193 1.853 29.07 55.0 17,214 3922 0.029 3588 (I > 2rðIÞ) 202 0.022 (I > 2rðIÞ) 0.047 0.99
b () 3 ) V (A Z T (K) Dcalc: (g cm3 ) l (cm1 ) 2h(max) () Reflections collected Unique reflections Rint Observations Variables R1 wR2 (for all reflections) Goodness of fit indicator
DI R D I F program system). Both of the structures were expanded using Fourier techniques DI R D I F 99. The non-hydrogen atoms were refined anisotropically. Hydrogen atoms were refined using the riding model for compound 2, while the hydrogen atoms of 1 were not dealt with due to the disorder of en. The final cycle of full-matrix least-squares refinement on F 2 was based on definite observed reflections and variable parameters, and converged with unweighted and weighted agreement factors of R1 and wR2 . A summary of the experimental details and selected results for compounds 1 and 2 is given in Table 1.
3. Results and discussion
2.4. Single crystal structure determination
3.1. Synthesis of the compounds
The measurement was carried out on a Rigaku Mercury CCD diffractometer using the x-scan method with graphite monochromated Mo Ka radiation (k ¼ 0:07107 nm) at )80 1 C. The X-ray diffraction data of single crystals were collected to a maximum 2h value of 55.0 for both 1 and 2. An empirical absorption correction was applied for all compounds and the data were corrected for Lorentz and polarization effects. The structure of 1 was solved by direct methods using the program of SH E L X 97 and the structure of 2 was solved by heavy-atom Patterson methods using PATTM (the
Single crystals of [Ni(en)3 ]2 Sn2 S6 (1) and [Ni(dien)2 ]2 Sn2 S6 (2) are obtained by using the reaction of SnCl4 5H2 O, NiCl2 6H2 O and S8 in the same molar ratio of Sn/Ni/S ¼ 1:1:4 (SnCl4 :NiCl2 :S8 ¼ 1:1:0.5) under mild solvothermal conditions in en and dien solvent, respectively. Stannic chloride was used as the source material instead of Sn powder which is usually used in synthesis of thiostannates under hydrothermal or solvothermal conditions [9,10,18]. The Ozin group had studied the Sn/S/amine (water solution) system in detail and isolated dimeric [Sn2 S6 ]4 and [S2 O3 ]2 reaction in-
D.-X. Jia et al. / Polyhedron 23 (2004) 937–942
939
termediates from the solution [11]. The redox disproportionation reaction of S8 is believed to be one of the sources of the S2 ion (as Eq. (1) [19]) which is used to form the [Sn2 S6 ]4 anion. þ 1=2S8 þ 9H2 O ! 2S2 þ S2 O2 3 þ 6H3 O
ð1Þ
In the case of the Sn4þ /S/en (dien) system in this work, the S2 ions which are necessary to form [Sn2 S6 ]4 might also come from disproportionation of S8 as Eq. (1), since the metal salts used are hydrated and the solvents are also not absolutely anhydrous. On the other hand, the ethylenediamine in this system might not only act as a solvent, but also offer a source of S2 (or S2 m ) by reacting with elemental sulphur: S þ en ! S2 ðor S2 m Þ þ ðHenÞ
þ
þ oxidized product of amine
ð2Þ
Reaction (2) is complicated and has not been studied in detail. When the sulphur reacts with en, a dark brown color is developed immediately and the species of S2 , þ S2 m and (Hen) have been confirmed by the products, such as (enH)4 [Sn2 S6 ], (enH)4 [Sn2 Se6 ] en, (enH)4 [Sn2 Te6 ] en [20] and [Mn(en)3 ]Te4 [21]. However, the mechanism of the synthetic reaction needs to be further confirmed. It is noteworthy that transition metal cations [Ni(en)3 ]2þ and [Ni(dien)2 ]2þ are likely better mineralizers than the protonated amines such as enHþ and dienHþ , because the products from the Ni2þ /Sn4þ /S/en (dien) system are [Ni(en)3 ]2 Sn2 S6 and [Ni(dien)2 ]2 Sn2 S6 rather than (enH)4 Sn2 S6 and (dienH)4 Sn2 S6 . If the nickel salts were not introduced into these systems under the same experimental conditions, crystallization of (enH)4 [Sn2 S6 ] is very difficult and the crystals were only obtained after the reaction solution had been left for about one month at room temperature.
Fig. 1. The structures of the transition metal complex cations in 1 (a) and 2 (b) with the labelling scheme and ellipsoids at 50% probability. Hydrogen atoms have been omitted for clarity.
3.2. Description of the structures The crystal structures of compounds 1 and 2 were determined by the single-crystal X-ray diffraction method. The results show that compound 1 crystallizes in the orthorhombic space group of Pbca (No. 61) and compound 2 in the monoclinic space group of P 21 =n (No. 14). Both compounds consist of discrete [Sn2 S6 ]4 anions with [Ni(en)3 ]2þ or [Ni(dien)2 ]2þ cations as counterions. The structure of compound 1 is essentially the same as that of [Ni(en)3 ]2 Sn2 S6 which was very recently synthesized by the Bensch group, but they use elemental nickel, tin and sulphur as starting reactants [18]. The Ni2þ ion is coordinated by six N atoms of three bidentate ethylenediamine ligands with Ni–N distances ranging The conformation of from 2.097(4) to 2.146(5) A. [Ni(en)3 ]2þ cation is difficult to fix due to the disorder of the ethylenediamine ligands. The configurations of the ligands are disordered with K ðdddÞ:D ðkkkÞ [or D ðkkkÞ :K ðdddÞ in inversion position] occupation ratios of 0.76:0.24 (Fig. 1(a)). In compound 2, the Ni2þ ion is coordinated by six N atoms of two trichelating dieth-
Table 2 and angles () for [Ni(en)3 ]2 Sn2 S6 (1) and [Ni(dien)2 ]2 Sn2 S6 (2) Selected bond distances (A) 1
2
1
2
Bond distances Ni–N1 Ni–N2 Ni–N3
2.108(4) 2.133(4) 2.137(4)
2.118(2) 2.143(2) 2.090(2)
Ni–N4 Ni–N5 Ni–N6
2.097(4) 2.116(4) 2.146(5)
2.133(2) 2.113(2) 2.102(2)
Sn–S1 Sn–S2
2.338(1) 2.347(1)
2.354(1) 2.334(1)
Sn–S3 Sn–S30
2.453(1) 2.457(1)
2.461(1) 2.453(1)
Bond angles (1) N–Ni–Ntrans: (3) N–Ni–Ntrans:
172.3(2) 169.7(2)
179.47(7) 177.56(7)
(2) N–Ni–Ntrans:
172.3(2)
177.52(8)
S1–Sn–S2 S1–Sn–S3 S2–Sn–S3 S1–Sn–S30
111.52(4) 114.58(4) 112.40(3) 112.20(3)
114.48(2) 113.24(2) 111.53(2) 110.59(2)
S2–Sn–S30 S3–Sn–S30 Sn–S3–Sn0
113.18(3) 91.61(4) 88.39(4)
112.07(2) 93.013(19) 86.987(19)
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Fig. 2. The structure of the [Sn2 S6 ]4 anion with the labelling scheme and ellipsoids at 50% probability.
[Sn2 S6 ]4 anion is surrounded by four [Ni(en)3 ]2þ cations in 1, and by six [Ni(dien)2 ]2þ cations in 2. Between the anion and cation in compound 2, a lot of short intermolecular N–H S interactions, which indicate weak hydrogen bonding, are found and one Sn2 S6 unit is hydrogen bonded to six different cations (Fig. 4(b)). The terminal S(1) and S(2) atoms form hydrogen bonds to H–N groups of [Ni(dien)2 ]2þ cations with H S distances ranging from 2.508(3) to 2.888(2) and N–H S angles ranging from 145.0(2) to A
ylenetriamine ligands. The conformation of octahedral [Ni(dien)2 ]2þ is s-facial (Fig. 1(b)). In compounds 1 and 2, The Ni–N bond lengths are within the range for compounds containing [Ni(en)3 ]2þ and [Ni(dien)2 ]2þ cations [22,23]. The [Ni(en)3 ]2þ and [Ni(dien)2 ]2þ octahedral coordination spheres are distorted, which can be seen from the N–Ni–Ntrans angles varying from 169.7(2) to 172.3(2) and 177.52(8) to 179.47(7), respectively. The three octahedral axial N– Ni–Ntrans angles of the coordination octahedra are listed in Table 2. The [Sn2 S6 ]4 anion, which is formed by the connection of two SnS4 tetrahedra sharing a common edge, can be described as a planar Sn2 S2 four-membered ring with each Sn atom having two terminal Sn–S bonds (Fig. 2). The terminal Sn–St bond lengths, being be are shorter than those of tween 2.334(1) and 2.354(1) A, the bridging Sn–Sb bonds which vary from 2.461(1) to Both kinds of bond lengths are in good 2.453(1) A. agreement with corresponding bond lengths in other compounds containing [Sn2 S6 ]4 anions [20,24]. The two SnS4 tetrahedra in the [Sn2 S6 ]4 dimer are slightly distorted, which is demonstrated by the St –Sn–St and St –Sn–Sb angles deviating from the ideal value of 109.5 (Table 2). The packing of [Sn2 S6 ]4 anions in compounds 1 and 2 is different (shown in Fig. 3). There are eight [Sn2 S6 ]4 anions at corners and six at crystal faces per unit cell of 1, while there are four [Sn2 S6 ]4 anions at crystal edges and two at crystal faces of [0 0 1] per unit cell of 2. One
Fig. 4. The views of the [Sn2 S6 ]4 anion hydrogen bonding interaction with cations in 1 (a) and 2 (b). Hydrogen atoms have been omitted for clarity.
Fig. 3. The packing of the [Sn2 S6 ]4 anions in 1 (a) and 2 (b), the cations have been omitted for clarity.
D.-X. Jia et al. / Polyhedron 23 (2004) 937–942 Table 3 Selected H S distances [Ni(dien)2 ]2 Sn2 S6
(A)
and
N–H S
angles
()
in
N–H
S
N–H
H S
N S
N–H S
N(1)–H(1) N(2)–H(4) N(4)–H(15) N(5)–H(17) N(6)–H(18) N(1)–H(2) N(3)–H(5) N(4)–H(14) N(5)–H(16)
S(1) S(1) S(1) S(1) S(1) S(2) S(2) S(2) S(2)
0.761(3) 0.875(4) 0.897(3) 0.885(3) 0.900(3) 0.915(3) 0.924(3) 0.942(3) 0.906(3)
2.812(2) 2.888(2) 2.571(2) 2.583(2) 2.527(2) 2.582(2) 2.705(2) 2.508(2) 2.846(2)
3.484(2) 3.639 3.453(2) 3.461(2) 3.394(2) 3.419(2) 3.561(2) 3.407(2) 3.676
148.5(2) 145.0(2) 168.2(2) 171.7(2) 161.6(2) 152.2(2) 154.5(2) 159.7(2) 153.0(2)
171.7(2) (Table 3). In compound 1, the number of interion interactions is less than that in 2 (Fig. 4(a)) and this difference might be the reason of disorder of the ethylenediamine in 1. The results show that [Ni(en)3 ]2þ and [Ni(dien)2 ]2þ cations have different structure-directing
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effects, although both of them are actually synthesized under the same conditions except for the amine. 3.3. Thermal analysis The thermal behavior of the title compounds were measured between temperatures of 20 and 600 C with the DSC-TGA method under nitrogen. The results are shown in Fig. 5. The first step mass loss of 1 (about 0.56% below 100 C) is attributed to desorption of water (Fig. 5(a)). Compound 1 is decomposed at 291 C accompanied by one endothermic peak in the DSC curve (peak temperature, Tp ). The corresponding loss of 40.8% is in accordance with the complete mass loss of six en ligands (Calc. 39.7% for 6 en). The decomposition of 2 is at 310 C (Tp of DSC) and the corresponding loss of 42.2% is in good agreement with the complete mass loss of the four dien ligands (Calc. 43.0% for 4 dien). From the behaviors of thermal decomposition, it is obvious that compounds 1 and 2 remove all of their organic amine ligands in one step under nitrogen. The decomposition temperature of 2 is higher than that of 1 by about 20 C. This result can be explained reasonably by the structure analysis that shows compound 2 has more N–H S hydrogen bonds than compound 1, which makes the organic ligands in 2 more difficult to remove.
4. Conclusions Single crystals of [Ni(en)3 ]2 Sn2 S6 and [Ni(dien)2 ]2 Sn2 S6 can be obtained by reaction of SnCl4 5H2 O, NiCl2 6H2 O and S8 under mild solvothermal conditions. The results presented in this paper demonstrate that the transition metal complex cations can act as a mineralizer in the synthesis of [Sn2 S6 ]4 thiostannates from the Ni(II)/Sn(IV)/S/en (dien) system using solvothermal techniques. The [Ni(en)3 ]2þ and [Ni(dien)2 ]2þ cations are likely a better mineralizer than protonated amines, such as enHþ and dienHþ . The different structure directing effect of [Ni(en)3 ]2þ and [Ni(dien)2 ]2þ cations is one of the reasons that [Sn2 S6 ]4 anions arrange in a different way in the crystal structures of compounds 1 and 2. Both title compounds lose all of their amine ligands in one step under nitrogen. The decomposition temperature of 2 is higher than that of 1 by about 20 C, accounting for the N–H S hydrogen bonding.
5. Supplementary data
Fig. 5. Thermogravimetric analyses curves of compounds 1 (a) and 2 (b).
Crystallographic data for the structural analyses have been deposited with the Cambridge Crystallographic Data Centre, CCDC nos. 217522 and 217523 for com-
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pounds 1 and 2, respectively. These data can be obtained free of charge via www.ccdc.cam.ac.uk/conts/retrieving.html or from the Cambridge Crystallographic Data Centre, 12 Union Road, Cambridge CB2 1EZ, UK; fax: (+44) 1223-336-033, or e-mail: [email protected].
Acknowledgements This work was supported by the National Natural Science Foundation (20071024, 20371033), P.R. China. The authors are also grateful to the Key Laboratory of Organic Synthesis of Jiangsu Province, Suzhou University, for financial support. References [1] C.L. Bowes, G.A. Ozin, Adv. Mater. 8 (1996) 13. [2] J. Llanos, C. Mujica, V. Sanchez, O. Pe~ na, J. Solid State Chem. 173 (2003) 78. [3] C.R. Evenson IV, P.K. Dorhout, Z. Anorg. Allg. Chem. 627 (2001) 2178. [4] U. Simon, F. Sch€ uth, S. Schunk, X. Wang, F. Liebau, Angew. Chem. Int. Ed. Engl. 36 (1977) 1121. [5] R.L. Glitzendanner, F.L. Di Salvo, Inorg. Chem. 35 (1996) 2623. [6] R.R. Chianelli, T.A. Pecoraro, T.R. Halber, W.-H. Pan, E.I. Stiefel, J. Catal. 86 (1984) 226.
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