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{Sn10Si(SiMe3)2[Si(SiMe3)3]4}2-: cluster enlargement via degradation of labile ligands

  • Claudio Schrenk und Andreas Schnepf EMAIL logo
Veröffentlicht/Copyright: 3. September 2013
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Main Group Metal Chemistry
Aus der Zeitschrift Main Group Metal Chemistry Band 36 Heft 5-6

Abstract

For the synthesis of metalloid cluster compounds of tin applying the disproportionation reaction of subvalent metastable Sn(I) halides, Si(SiMe3)3 proved to be the ligand with the highest synthetic potential. However, degradation of the Si(SiMe3)3 ligand can also lead to cluster enlargement where additional silicon atoms are incorporated into the cluster core. Here we describe the structure and bonding of the novel anionic cluster compound {Sn10Si(SiMe3)2[Si(SiMe3)3]4}2- 5, where such a degradation has taken place. Additionally, requirements for the formation of 5 are discussed.

Keywords: metalloid cluster; silicon; tin

Introduction

Due to recent developments in nanotechnology, the area between molecules and the solid state becomes more and more interesting also from an industrial point of view. From a fundamental point of view this area is of particular interest for metals or semimetals, as drastic changes in properties take place on an ongoing basis from the element to the molecular precursors.

To explain this area, metalloid clusters of the general formulae MnRm (M=metal atom like Au, Al, Sn, etc., R=ligand like HS-C6H5, tBu, N(SiMe3)2, etc.; n>m) are ideal model compounds (Driess and Nöth, 2004; Schnepf, 2007b; Schnöckel and Schnepf, 2011). However, metalloid clusters are metastable intermediates, and thus, special synthetic routes are necessary to gain access to these compounds. In the case of tin, first, reductive coupling reactions of halides or hydrides were used to synthesize metalloid clusters with up to 17 tin atoms in the cluster core (Wiberg et al., 1999; Eichler and Power, 2001; Richards et al., 2003, 2005; Brynda et al., 2006; Rivard et al., 2007; Prabusankar et al., 2008). Thereby the naked tin atoms mainly result from ligand stripping reactions.

Another possibility to get access to metalloid clusters applies the disproportionation reaction of a subvalent metastable halide (Schnepf, 2010). During this disproportionation reaction, metalloid clusters might be trapped as intermediates on the way to the solid state by substitution of the halides by bulky ligands as emphasized in Scheme 1; that is, the tin core of the metalloid cluster is now shielded by a ligand shell so that these clusters are kinetically stabilized and can be isolated.

Scheme 1 Synthetic concept for the preparation of a metalloid tin cluster applying the disproportionation reaction of a subvalent halide.
Scheme 1

Synthetic concept for the preparation of a metalloid tin cluster applying the disproportionation reaction of a subvalent halide.

For kinetic stabilization, low temperatures are needed; that is, the subvalent halides used in this synthetic route (Scheme 1) must disproportionate at low temperatures, and thus only tin(I) halides are useful as they disproportionate well below 0°C (Schrenk et al., 2009). However, for the synthesis of metastable solutions of Sn(I) halides, the special synthetic procedure of preparative co-condensation is necessary (Köppe and Schnepf, 2002). Thereby it becomes obvious that the stability of the subhalide solution mainly depends on the donor used as well as on the halide:Sn ratio obtained during the reaction (Pacher et al., 2010); that is, during the synthesis a small amount of the Sn(II) halide is always present as well. The ratio of Sn(I) to Sn(II) thereby depends on the temperature and pressure applied during the co-condensation reaction (Schrenk et al., 2009).

Starting from Sn(I) halide emulsions, we recently have shown that metalloid clusters with up to 10 tin atoms like Sn10[Si(SiMe3)3]6 1 can be obtained (Schrenk et al., 2010) when LiSi(SiMe3)3 is used as the ligand source (Schrenk et al., 2012a,b,c). Additionally, we have shown that on the oxidative side of the disproportionation reaction, rings and clusters are formed like the stanna-cyclopropene Sn3[Si(SiMe3)3]4 2 (Schrenk and Schnepf, 2010), where the shortest tin-tin double bond is realized as the ligands are forced into a planar arrangement. When a higher amount of Sn(II) is present a further reaction of 2 with the Sn(II) compound Sn[Si(SiMe3)3]2 can take place, leading to the polyhedral cluster Sn4Si(SiMe3)2[Si(SiMe3)3]4 3 where a Si(SiMe3)3 ligand is decomposed, leading to a silicon atom that is incorporated into the cluster core (Schrenk et al., 2011). Such a degradation of the ligand might also take place on the reductive side of the disproportionation reaction, and in the following we present a recent result in this respect.

Results and discussion

The reaction of a metastable Sn(I)Br or Sn(I)Cl emulsion exhibiting a Br:Sn ratio of ca. 1.21 with LiSi(SiMe3)3 leads to the neutral Sn10 cluster 1 in a moderate yield of 10%. Besides the neutral cluster 1, the anionic cluster {Sn9[Si(SiMe3)3]3}- 4 could be obtained after further work-up of the reaction mixture. When now a metastable Sn(I)Br emulsion, featuring a Br:Sn ratio of ca. 1.6 is applied, i.e., the amount of SnBr2 is significantly higher, only a couple of black crystals of 1 are obtained during work-up of the reaction mixture. This result shows that the Br:Sn ratio within the subhalide solution significantly influences the reaction course. Nevertheless, further work-up of the reaction mixture now leads to tiny black, needle like crystals. X-ray crystal structure analysis of these crystals reveals that now the novel anionic metalloid cluster compound {Sn10Si(SiMe3)2[Si(SiMe3)3]4}2- 5 has formed, which crystallizes with two {Li[12-crown-4]2}+ counter cations in the monoclinic crystal system in space group P2(1)/c (Figure 1).

Figure 1 Molecular structure of {Sn10Si(SiMe3)2[Si(SiMe3)3]4}2-5; thermal ellipsoids with 25% probability. Selected bond distances (pm) and angles (°): Sn1-Sn5: 292.6(2); Sn1-Sn8: 298.1(2); Sn1-Sn9: 297.1(2); Sn5-Sn2: 292.1(2); Sn5-Sn9: 323.2(2); Sn5-Sn3: 299.1(2); Sn3-Sn10: 294.2(2); Sn9-Sn10: 302.0(2); Sn10-Sn8: 296.5(2); Sn10-Sn7: 321.5(2); Sn10-Sn4: 298.3(2); Sn4-Sn8: 299.7(2); Sn4-Sn6: 295.2(2); Sn6-Sn1: 290.9(2); Sn6-Si5: 266.4(5); Sn2-Si5: 260.0(6); Sn1-Si1: 262.5(5); Sn2-Si2: 264.7(6); Sn3-Si3: 265.7(6); Sn4-Si4: 264.9(6); Si3-Si30: 235.3(8); Si3-Si31: 235.7(8); Si3-Si32: 235.1(8); Si5-Si50: 233.5(8); Si5-Si51: 235.7(8); Si31-C31a: 189(2); Si31-C31b: 189(2); Si31-C31c: 190(2); Si32-C32a: 189(2); Si32-C32b: 185(2); Si32-C32c: 188(2); Sn2-Si5-Sn6: 104.4(2); Sn9-Sn10-Sn8: 59.72(5); Sn4-Sn10-Sn7: 56.41(4); Sn5-Sn1-Sn6: 117.87(6), Si4-Sn4-Sn7: 111.26(13); Si1-Sn1-Sn8: 101.76(13); Si32-Si3-Si31: 107.8(3).
Figure 1

Molecular structure of {Sn10Si(SiMe3)2[Si(SiMe3)3]4}2-5; thermal ellipsoids with 25% probability. Selected bond distances (pm) and angles (°): Sn1-Sn5: 292.6(2); Sn1-Sn8: 298.1(2); Sn1-Sn9: 297.1(2); Sn5-Sn2: 292.1(2); Sn5-Sn9: 323.2(2); Sn5-Sn3: 299.1(2); Sn3-Sn10: 294.2(2); Sn9-Sn10: 302.0(2); Sn10-Sn8: 296.5(2); Sn10-Sn7: 321.5(2); Sn10-Sn4: 298.3(2); Sn4-Sn8: 299.7(2); Sn4-Sn6: 295.2(2); Sn6-Sn1: 290.9(2); Sn6-Si5: 266.4(5); Sn2-Si5: 260.0(6); Sn1-Si1: 262.5(5); Sn2-Si2: 264.7(6); Sn3-Si3: 265.7(6); Sn4-Si4: 264.9(6); Si3-Si30: 235.3(8); Si3-Si31: 235.7(8); Si3-Si32: 235.1(8); Si5-Si50: 233.5(8); Si5-Si51: 235.7(8); Si31-C31a: 189(2); Si31-C31b: 189(2); Si31-C31c: 190(2); Si32-C32a: 189(2); Si32-C32b: 185(2); Si32-C32c: 188(2); Sn2-Si5-Sn6: 104.4(2); Sn9-Sn10-Sn8: 59.72(5); Sn4-Sn10-Sn7: 56.41(4); Sn5-Sn1-Sn6: 117.87(6), Si4-Sn4-Sn7: 111.26(13); Si1-Sn1-Sn8: 101.76(13); Si32-Si3-Si31: 107.8(3).

The Sn10 cluster core of 5 can be described as a distorted centaur polyhedral arrangement of the 10 tin atoms, where at the icosahedral side two Sn-Sn distances (Sn7-Sn10, Sn5-Sn9) are significantly elongated (321 and 325 pm). The other Sn-Sn distances within the cluster core are in the normal range (290–302 pm) as observed within metalloid Sn10 clusters featuring a centaur polyhedral arrangement (Schrenk et al., 2010, 2012a,b,c). Hence, the Sn-Sn distances within 5 are longer in the icosahedral part and vary between 294 and 302 pm (average value: 298.5 pm), whereas the Sn-Sn distances in the cubic part are shorter and vary between 290 and 295 pm (average value: 292.4 pm).

Two tin atoms in the cubic part are bound to the silicon atom of the Si(SiMe3)2 group (Si5) with Sn-Si distances of 260 and 266 pm, being thus in the same range as the other Sn-Si distances in 5. The Si(SiMe3)2 group (Si5) must thereby originate from the degradation of a Si(SiMe3)3 ligand, as is frequently observed in cluster chemistry when Si(SiMe3)3 is used as a ligand, e.g., in the case of Sn4Si(SiMe3)2[Si(SiMe3)3]4 3 (vide infra) or during the synthesis of {(SiMe3)2SiE4[Si(SiMe3)3]3}-, (E=Ga, Al) (Linti et al., 1998; Vollet et al., 2007) and {Ge10Si[Si(SiMe3)3]4 (SiMe3)2Me}- (Schnepf, 2007a). Additionally, such a decomposition of the Si(SiMe3)3 ligand is observed in the gas phase within collision-induced dissociation experiments of {Ge9[Si(SiMe3)3]3}-, leading at the end to [Ge9Si]- where also one silicon atom of a Si(SiMe3)3 ligand is incorporated in the cluster core (Koch et al., 2006; Schenk et al., 2010).

Interestingly, the Si(SiMe3)3 ligand (Si3), which is directly opposite to the silicon atom of the Si(SiMe3)2 group, is oriented nearly perpendicular to the Sn3 plane Sn3-Sn9-Sn10, leading to bond angles of approximately 90° (Figure 2). Additionally, the ligand bound tin atom Sn3 is surrounded by Sn5, Sn7, and the ligand (Si3) in a planar arrangement (sum of bond angles: 360°). Such an arrangement of the Si(SiMe3)3 ligand is unusual as stabilizing ligands are normally bound to the cluster core in such a way that they point radially outward, as is the case for the other Si(SiMe3)3 ligands in 5. Nevertheless, the SiMe3 ligands completely shield the cluster core as it is obvious from the space filling model (Figure 2), indicating that the ligands are interlocked. For further discussion and nuclear magnetic resonance (NMR) investigations see the experimental section and the supporting information.

Figure 2 Left: molecular structure of {Sn10Si(SiMe3)2[Si(SiMe3)3]4}2- 5 without methyl groups (the Sn3 plane is emphasized), angle between Sn3-plane and Si3: 90.08(1)°. Right: space-filling model of 5 (view along the same direction as used for the ball-and-stick presentation on the left side).
Figure 2

Left: molecular structure of {Sn10Si(SiMe3)2[Si(SiMe3)3]4}2- 5 without methyl groups (the Sn3 plane is emphasized), angle between Sn3-plane and Si3: 90.08(1)°. Right: space-filling model of 5 (view along the same direction as used for the ball-and-stick presentation on the left side).

To elucidate if the perpendicular orientation of one ligand (Si3) is the result of steric effects, quantum chemical calculations2 were done on {Sn10Si(SiMe3)2[Si(SiMe3)3]4}2- 5 as well as on the model compound {Sn10Si(SiH3)2[(Si(SiH3)3]4}2- 5a, where the methyl groups are substituted by less bulky hydrogen atoms. The calculated structure for 5 is in good accordance with the experimentally determined one. Additionally, the calculations reveal that in both cases (5 and 5a) the ligand is oriented nearly perpendicular to the Sn3 plane (Sn3-Sn9-Sn10), showing that electronic effects are mainly responsible for this unusual orientation. However, steric effects increase the observed arrangement as the calculated angle between the Sn3 plane Sn3-Sn9-Sn10 and the silicon atom of the ligand is 92.8° for 5 (experiment: 90.08°) and 93.3 for 5a. Also, the planar coordination at Sn3 is very similar; that is, the sum of bond angles is 360° within 5 and 359.6° in the less bulky 5a. Due to this unusual arrangement of the Si(SiMe3)3 ligand, the covalent bond between the tin and silicon atom might exhibit nearly pure p-character and a good representative for this bond can be found in HOMO-12 (Figure 3).

Figure 3 Representation of HOMO-12 of {Sn10Si(SiMe3)2[Si(SiMe3)3]4}2- 5.
Figure 3

Representation of HOMO-12 of {Sn10Si(SiMe3)2[Si(SiMe3)3]4}2- 5.

Further analysis of the bonding within {Sn10Si(SiMe3)2 [Si(SiMe3)3]4}2- 5 was performed with the aid of an Ahlrichs-Heinzmann population analysis, showing that the shared electron numbers (SENs)3 of the two center bonding components within the cluster core nicely correlate with the Sn-Sn bond distance; that is, for the short Sn-Sn bond of 289.9 pm (Sn2-Sn7) a 2c-SEN of 0.93 is calculated. Besides this the 2c-SEN for the long Sn-Sn bond of 321.5 pm (Sn7-Sn10) is only 0.62. In addition to the two center bonding components, also three center bonding components with SENs up to 0.24 (Sn4-Sn8-Sn10) are calculated, indicating that the bonding electrons are delocalized within the cluster core (a complete presentation of all 2c-SEN and 3c-SEN is given in the supporting information). Thereby, larger 3c-SENs are calculated within the icosahedral part of the centaur polyhedron, an aspect that is well known for metalloid tin clusters, exhibiting a centaur polyhedral arrangement of tin atoms (Schrenk et al., 2010, 2012a).

However, the centaur polyhedral arrangement of the tin atoms in 5 is strongly distorted. The distortion is thereby very similar to the one found within the anionic metalloid Sn10 cluster {Sn10[Si(SiMe3)3]5}- 6 (Schrenk et al., 2012a); that is, in the case of 6 also two Sn-Sn distances are elongated with respect to the centaur polyhedral arrangement observed within the neutral cluster Sn10[Si(SiMe3)3]6 7 (Figure 4).

Figure 4 Arrangement of the tin atoms within the cluster core of {Sn10Si(SiMe3)2[Si(SiMe3)3]4}2- 5 (left) and {Sn10[Si(SiMe3)3]5}- 6 (right). From the ligands, only the central Si atoms are shown. The elongated Sn-Sn distances are marked in orange.
Figure 4

Arrangement of the tin atoms within the cluster core of {Sn10Si(SiMe3)2[Si(SiMe3)3]4}2- 5 (left) and {Sn10[Si(SiMe3)3]5}- 6 (right). From the ligands, only the central Si atoms are shown. The elongated Sn-Sn distances are marked in orange.

Such a similar distortion hints at a common starting point for 5 and 6, which might be the anionic cluster {Sn9[Si(SiMe3)3]3}- 4 (Schrenk et al., 2012b). Hence, starting from {Sn9[Si(SiMe3)3]3}- 4 the addition of the stannylene Sn[Si(SiMe3)3]2 leads to {Sn10[Si(SiMe3)3]5}- 6. The addition of the anionic stannide {Sn[Si(SiMe3)3]3}-, however, leads to the hypothetical {Sn10[Si(SiMe3)3]6}2- 8 from which, after the elimination of Si(SiMe3)4, the product {Sn10Si(SiMe3)2[Si(SiMe3)3]4}2- 5 is formed (Scheme 2). Because the lithium salt LiSi(SiMe3)3 is used in excess and a large amount of SnCl2 was present during the reaction, such a reaction sequence seems plausible.

Scheme 2 Probable reaction sequence for the formation of {Sn10Si(SiMe3)2[Si(SiMe3)3]4}2- 5 and {Sn10[Si(SiMe3)3]5}- 6 from {Sn9[Si(SiMe3)3]3}- 4. The molecular structures of 4, 5, and 6 are given in ball-and-stick presentation without CH3 groups.
Scheme 2

Probable reaction sequence for the formation of {Sn10Si(SiMe3)2[Si(SiMe3)3]4}2- 5 and {Sn10[Si(SiMe3)3]5}- 6 from {Sn9[Si(SiMe3)3]3}- 4. The molecular structures of 4, 5, and 6 are given in ball-and-stick presentation without CH3 groups.

Additionally quantum chemical calculations reveal that the formation of 5 or 6 from 4 via the reaction sequence shown in Scheme 2 is only slightly endergonic by 41 and 24 kJ/mol, respectively. This possible reaction sequence further underlines the central importance of Sn9 units in tin cluster chemistry, being also obvious within naked gas phase clusters, where Sn9 subunits are present within larger clusters (Oger et al., 2009; Debrov et al., 2010; Lechtken et al., 2010). The special role of the E9 unit is also obvious from the area of Zintl anions where Sn9x- (x=2–4) anions are the most prominent starting material (Fässler, 2001; Sevov and Goicoechea, 2001; Scharfe and Fässler, 2010). However, the results presented here are just first steps to an understanding of the reaction course taking place during the formation of metalloid clusters from smaller units.

Summary

The synthesis of the novel metalloid tin cluster compound {Sn10Si(SiMe3)2[Si(SiMe3)3]4}2- 5 is described, starting from a subhalide emulsion with a large Br:Sn ratio of 1.6, showing that the Br:Sn ratio has a significant influence on the reaction course in general. Within the structure of 5 a Si(SiMe3)2 group is present, resulting from ligand degradation, showing that the Si(SiMe3)3 ligand can also be part of subsequent reactions that lead in the case of 5 to a cluster enlargement. The distorted centaur polyhedral arrangement of the 10 tin atoms as well as the bonding in 5 are discussed, showing that 5 fits well within the field of metalloid tin clusters, featuring delocalized bonding electrons. However, one ligand is bound to the cluster core in an unusual perpendicular arrangement, showing that ligands must not always be oriented radially outward as is normally observed in ligand-stabilized clusters. The similarity of the distortion of the centaur polyhedron within {Sn10Si(SiMe3)2[Si(SiMe3)3]4}2- 5 to the one found within the monoanionic metalloid cluster {Sn10[Si(SiMe3)3]5}- 6 hints to a common starting point, which might be the metalloid cluster {Sn9[Si(SiMe3)3]3}- 4. Quantum chemical calculations show that the formation of 5 and 6 from 4 is only slightly endergonic, giving a first insight into the reaction course taking place during the formation of metalloid clusters further underlining the special role of E9 units in the cluster chemistry of tin.

Experimental

Synthesis of {Sn10Si(SiMe3)2[Si(SiMe3)3]4}2-⋅ 2{Li(12-crown-4)2}+

In a homemade co-condensation apparatus (Köppe and Schnepf, 2002) metallic tin was treated at 1200°C with a continuous flow of HBr (20 mmol) at a flow rate of ca. 0.18 mmol/min. During the reaction, 1.5 g (12.6 mmol) of tin was consumed and the resulting gas particles were condensed together with 200 mL of a mixture of toluene and tributylamine in a volume ratio of 4:1 at -196°C. The amount of tin (12.6 mmol) and HBr (20 mmol) consumed during the reaction leads to a Br-Sn ratio of 1.59. After warming up the reaction vessel to −78°C, a precooled solution of 10.3 g (22 mmol) (thf)3LiSi(SiMe3)3 in approximately 100 mL of toluene was added to the subhalide emulsion. The resulting mixture was stirred for 1.5 h while it was allowed to slowly warm up to room temperature. The nearly black reaction mixture was transferred into a Schlenk tube and stored for 1 day at room temperature. After 1 day a black, oily residue appeared. This oil was isolated and dissolved in 20 mL of Et2O, treated with a small amount of 12-crown-4, and stored at 6°C. After 1 week, a few small crystalline, black needles of {Li(12-crown-4)2}2{Sn10Si(SiMe3)2[(Si(SiMe3)3]4} (50 mg, 0.016 mmol, 0.8% yield with respect to tin) were isolated.

NMR

Crystals of {Sn10Si(SiMe3)2[Si(SiMe3)3]4}2- 5 2{Li(12-crown-4)2}+⋅2Et2O were dissolved in THF-d8 within an NMR tube that was flame sealed and used for measurements on a Bruker Avance 300 spectrometer at 300 K. The proton NMR (see supporting information) shows a variety of signals for the protons of the SiMe3 groups, indicating distorted free rotation. However, 5 is not stable in solution as the dark brown color of the solution vanishes after 2 h and a gray precipitate occurs. Such a behavior was previously observed for the anionic {Sn9[Si(SiMe3)3]2}2- cluster 9, which also decomposes in solution (Schrenk et al., 2012c). However, in the case of 9 the decomposition time could be extended on complexing the cation by 12-crown-4. In the case of 5 the cation is already complexed by the crown ether; that is, 5 is more reactive in solution than 9 and NMR investigations on 5 are not possible.

X-ray crystallography

Table 1 contains the crystal data and details of the X-ray structural determination for {Sn10Si(SiMe3)2[Si(SiMe3)3]4}{Li(12-crown-4)2}2⋅2Et2O. The data were collected at 100 K on a Bruker APEX II diffractometer employing monochromated Mo(Kα, 0.71073 Å) radiation from a sealed tube and equipped with an Oxford Cryosystems cryostat. A numeric absorption correction was applied using the optically determined shape of the crystals. Due to the small size of the crystals the reflections are very weak, leading to an unsatisfactory Rint of 13.38%. Nevertheless, the structure could be readily solved, leading to satisfactory temperature factors for all atoms within the cluster. The structure was solved by direct methods and refined by full-matrix least-squares techniques using the programs SHELXS and SHELXL (Sheldrick, 2008). The nonhydrogen atoms were refined anisotropically and the hydrogen atoms were calculated using a riding model. CCDC-934891 contains the supplementary crystallographical data for this paper. These data can be obtained online free of charge at www.ccdc.cam.ac.uk/conts/retrieving.html or from Cambridge Crystallographic Data Centre, 12 Union Road, Cambridge CB21EZ; Fax: +44-1223-336-033; or deposit@ccdc.cam.ac.uk.

Table 1

Crystal data and details of structural determinations.

{Sn10Si(SiMe3)2[Si(SiMe3)3]4}2-⋅2{Li(12-crown-4)2}+⋅2Et2O
FormulaSn10Si19Li2C82O18H210
Formula wt.3218.99
T (K)100
Crystal systemMonoclinic
Space groupP2(1)/c
a (Å)15.208(1)
b (Å)32.431(2)
c (Å)29.509(2)
α (°)90
β (°)94.698(4)
γ (°)90
V (Å3)14.505(2)
Z4
µ/mm1.474
δ (g/cm3)1.893
Reflections measured131,203
Reflections observed (I>2σI)20,998
Rint0.1338
Goof1.053
R1 (I<2σ)0.0847
wR2 (all data)0.2181
Corresponding author: Andreas Schnepf, Faculty of Science, Institute of Inorganic Chemistry, University of Tübingen, Auf der Morgenstelle 18, D-72076 Tübingen, Germany, e-mail:
  1. 1

    During the synthesis of the high-temperature molecules besides the monohalides SnX (X=halide: Cl, Br) a certain amount of Sn(II) halide (SnX2) is also formed, depending on the temperature and pressure applied during the reaction. Consequently, the halide-tin ratio is always larger than 1 depending on the amount of the Sn(II) halide. Hence, within a solution exhibiting a halide-tin ratio of 1.2 the proportion of SnX to SnX2 is 4:1.

  2. 2

    Quantum-chemical calculations were carried out with the RI-DFT version of the Turbomole program package (Turbomole GmbH, Karlsruhe, Germany) by employing the Becke-Perdew 86-functional. The basis sets were of SVP quality. The electronic structure was analyzed with the Ahlrichs-Heinzmann population analysis based on occupation numbers (Davidson, 1967; Roby, 1974; Heinzmann and Ahlrichs, 1976; Erhardt and Ahlrichs, 1985; Perdew, 1986; Becke, 1988; Schäfer et al., 1992; Eichkorn et al., 1995; Treutler and Ahlrichs, 1995).

  3. 3

    The SENs for bonds are a reliable measure of the covalent bonding strength. For example, the SENs for the Sn-Sn single bond in the model compound R3Sn-SnR3 (R=H, CH3, SiH3) are 1.27(H), 1.07(CH3), and 1.11(SiH3), respectively.

We thank the Deutsche Forschungsgemeinschaft (DFG) for financial support.

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Received: 2013-6-14
Accepted: 2013-7-30
Published Online: 2013-09-03
Published in Print: 2013-12-01

©2013 by Walter de Gruyter Berlin Boston

This article is distributed under the terms of the Creative Commons Attribution Non-Commercial License, which permits unrestricted non-commercial use, distribution, and reproduction in any medium, provided the original work is properly cited.

Artikel in diesem Heft

  1. Masthead
  2. Masthead
  3. Review
  4. Structural characterization of heterometallic platinum complexes with non-transition metals. Part V: Heterooligo- and heteropolynuclear complexes
  5. Research Articles
  6. {Sn10Si(SiMe3)2[Si(SiMe3)3]4}2-: cluster enlargement via degradation of labile ligands
  7. Unusual reaction pathways of gallium(III) silylamide complexes
  8. Molecular structures of pyridinethiolato complexes of Sn(II), Sn(IV), Ge(IV), and Si(IV)
  9. Arylphosphonic acid esters as bridging ligands in coordination polymers of bismuth
  10. Synthesis of germanium dioxide nanoparticles in benzyl alcohols – a comparison
  11. X-ray crystal structures of [(Cy2NH2)]3[C6H3(CO2)3]·4H2O and [i-Bu2NH2][(Me3 SnO2C)2C6H3CO2]
  12. Crystal and molecular structure of bis(di-n-propylammonium) dioxalatodiphenylstannate, [n-Pr2NH2]2[(C2O4)2SnPh2]
  13. Short Communication
  14. Synthesis and structural characterization of a dimeric N,N-dimethylformamide solvate of isobutyltin(IV) dichloride hydroxide, [iBuSnCl2(OH)(DMF)]2
https://doi.org/10.1515/mgmc-2013-0031
Schlagwörter für diesen Artikel
metalloid cluster; silicon; tin
Creative Commons
BY-NC-ND 3.0

Artikel in diesem Heft

  1. Masthead
  2. Masthead
  3. Review
  4. Structural characterization of heterometallic platinum complexes with non-transition metals. Part V: Heterooligo- and heteropolynuclear complexes
  5. Research Articles
  6. {Sn10Si(SiMe3)2[Si(SiMe3)3]4}2-: cluster enlargement via degradation of labile ligands
  7. Unusual reaction pathways of gallium(III) silylamide complexes
  8. Molecular structures of pyridinethiolato complexes of Sn(II), Sn(IV), Ge(IV), and Si(IV)
  9. Arylphosphonic acid esters as bridging ligands in coordination polymers of bismuth
  10. Synthesis of germanium dioxide nanoparticles in benzyl alcohols – a comparison
  11. X-ray crystal structures of [(Cy2NH2)]3[C6H3(CO2)3]·4H2O and [i-Bu2NH2][(Me3 SnO2C)2C6H3CO2]
  12. Crystal and molecular structure of bis(di-n-propylammonium) dioxalatodiphenylstannate, [n-Pr2NH2]2[(C2O4)2SnPh2]
  13. Short Communication
  14. Synthesis and structural characterization of a dimeric N,N-dimethylformamide solvate of isobutyltin(IV) dichloride hydroxide, [iBuSnCl2(OH)(DMF)]2
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