Synthesis, molecular structure, and isomerisation in solution of (ME 3SbS)2Me2SnCl2. Concomitant hypercoordination of tin and antimony

Article abstract of DOI:10.1002/zaac.200300102

The reaction of Me₃SbCl₂ and (Me₂SnS) ₃ afforded the complex (Me₃SbS)₂Me ₂SnCl₂ in high yields, whose molecular structure features both hypercoordinated tin and antimony atoms. In solution, (Me ₃SbS)₂Me₂SnCl₂ undergoes a reversible dissociation and ligand interchange reaction to give Me ₃SbS, Me₃SbCl₂ and (Me₂SnS) ₃.

Full text of DOI:10.1002/zaac.200300102

Synthesis, Molecular Structure, and Isomerisation in Solution of
(Me3SbS)2Me2SnCl2. Concomitant Hypercoordination of Tin and Antimony
Jens Beckmann*, Dainis Dakternieks, Andrew Duthie and Richard C. Foitzik
Geelong / Australia, Deakin University, Centre for Chiral and Molecular Technologies
Received April 9th, 2003.
Abstract. The reaction of Me3SbCl2 and (Me2SnS)3 afforded the
complex (Me3SbS)2Me2SnCl2 in high yields, whose molecular
structure features both hypercoordinated tin and antimony atoms.
sociation and ligand interchange reaction to give Me3SbS,
Me3SbCl2 and (Me2SnS)3.
Keywords: Tin; Antimony; Hypercoordination; Crystal structures;
NMR spectroscopy
In solution, (Me3SbS)2Me2SnCl2 undergoes
a reversible dis-
Synthese, Molekülstruktur und Isomerisierung von (Me3SbS)2Me2SnCl2 in Lösung.
Gleichzeitig auftretende Hyperkoordination am Zinn und Antimon
Inhaltsübersicht. In der Reaktion von Me3SbCl2 mit (Me2SnS)3 ent-
stand in hoher Ausbeute der Komplex (Me3SbS)2Me2SnCl2, dessen
Molekülstruktur sowohl hyperkoordinierte Zinn- als auch Anti-
monatome aufweist. In Lösung unterliegt (Me3SbS)2Me2SnCl2 ei-
ner reversiblen Dissoziation- und Ligandenaustauschreaktion bei
der Me3SbS, Me3SbCl2 und (Me2SnS)3 entstehen.
Introduction
Some 50 years ago Moedritzer and Van Walzer described
that mixtures of dimethyltin sulfide, (Me2SnS)3, and di-
methyltin dichloride, Me2SnCl2, rapidly undergo ligand in-
terchange of chlorine and sulfur atoms and exist in equilib-
rium with open-chain species ClMe2Sn(Me2SnS)nCl
(Scheme 1) [1]. In preceding work, we and others reported
that upon addition of chloride anions to such mixtures with
n ϭ 1, a hypercoordinated dinuclear organotin complex [µ-
Cl(Me2SnCl)2S]Ϫ is formed (Scheme 1) [2]. In the context
of this work we also investigated the reaction of dimethyltin
sulfide, (Me2SnS)3, and trimethylantimony dichloride,
Me3SbCl2, and isolated a crystalline organotin-organoanti-
mony complex, namely (Me3SbS)2Me2SnCl2. Apparently,
the same material was already obtained in 1967 by Shindo
and Okawara from the direct reaction of Me3SbS with
Me2SnCl2 [3,4]. We now describe its complete characteriz-
ation by NMR spectroscopy and X-ray crystallography.
Scheme 1
Discussion
The reaction of (Me2SnS)3 and Me3SbCl2 afforded the
complex (Me3SbS)2Me2SnCl2 in high yields (Eq. (1)).
(Me3SbS)2Me2SnCl2 comprises a colourless crystalline
material that is air-stable for several days and indefinitely
stable when stored under exclusion from light and air. The
Figure 1 General view (DIAMOND) of (Me3SbS)2Me2SnCl2
showing 40 % probability displacement ellipsoids and the atom
numbering scheme (Symmetry operations used to generate equiva-
lent atoms: a ϭ Ϫx, Ϫy, Ϫz).
* Dr. Jens Beckmann
Deakin University, Centre for Chiral and Molecular Technologies
Geelong 3217/Australia
Fax: ϩϩ61-3-5227-1040
E-mail: beckmann@deakin.edu.au
stability is noteworthy as most previous publications high-
light the limited stability of trialkylantimony sulfides [5].
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DOI: 10.1002/zaac.200300102
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Synthesis, Molecular Structure, and Isomerisation in Solution of (Me3SbS)2Me2SnCl2
˚
respectively. The 13C MAS NMR spectrum reveals three of
the four expected signals at δ 43.0, 13.8 and 11.3. The res-
onance at δ 43.0 displays unresolved tin satellites and thus
allows an unambiguous assignment to the Me2Sn group.
The large (1J(13C-119/117Sn) coupling of 1004 Hz is fully
consistent with the C(1)ϪSn(1)ϪC(1a) angle of 180° and
the underlying relationship proposed by Lockhart et al.
[9Ϫ11]. The signals at δ 13.8 and 11.3 were assigned to the
Me3Sb group. Based on the higher intensity of the latter
signal the expected third signal of the Me3Sb group is likely
to be superimposed. The arrangement of the Sb atoms lies
midway between a tetrahedron and a trigonal bipyramid
(geometrical goodness [12] ∆Σ(θ) 18.5°) and is defined by a
C3S donor set and an additional intramolecular Cl contact
(4ϩ1 coordination). Somewhat contradicting Bent’s rule,
two carbon atoms and one sulfur atom occupy the equa-
torial positions whereas the remaining carbon atom and the
chlorine atom are situated in the axial positions. The indi-
vidual SbϪC bond lengths differ only slightly from the
Table 1 Selected bond lengths/A and angles/° for (Me3SbS)2-
Me2SnCl2.
Sn(1)ϪC(1)
Sn(1)ϪS(1)
Sb(1)ϪC(3)
Sb(1)ϪS(1)
C(1)ϪSn(1)ϪC(1a)
C(1)ϪSn(1)ϪCl(1a)
C(1)ϪSn(1)ϪS(1a)
Cl(1)ϪSn(1)ϪS(1)
S(1)ϪSn(1)ϪS(1a)
C(2)ϪSb(1)ϪC(4)
C(2)ϪSb(1)ϪS(1)
C(4)ϪSb(1)ϪS(1)
2.126(3)
2.746(1)
2.108(3)
2.305(1)
180
90.39(10)
89.58(9)
93.12(2)
180
Sn(1)ϪCl(1)
Sb(1)ϪC(2)
Sb(1)ϪC(4)
Sb(1)ϪCl(1)
C(1)ϪSn(1)ϪCl(1)
C(1)ϪSn(1)ϪS(1)
Cl(1)ϪSn(1)ϪCl(1a)
Cl(1)ϪSn(1)ϪS(1a)
C(2)ϪSb(1)ϪC(3)
C(3)ϪSb(1)ϪC(4)
C(3)ϪSb(1)ϪS(1)
Sn(1)ϪS(1)ϪSb(1)
2.597(1)
2.103(3)
2.100(3)
3.577(1)
89.61(10)
90.42(9)
180
86.88(2)
112.57(14)
105.08(13)
113.06(9)
106.76(3)
108.15(14)
111.75(9)
105.63(9)
Symmetry operations used to generate equivalent atoms: a ϭ Ϫx, Ϫy, Ϫz
˚
average value of 2.104(3) A. The SbϪS bond length
˚
amounts to as 2.305(1) A and is slightly longer than in
˚
Ph3SbS (SbϪS: 2.245(6) A), the only triorganoantimony
sulfide yet investigated by X-ray diffraction [13]. The Sb···Cl
˚
distance of 3.577(1) A is shorter than the sum of van-der-
˚
˚
˚
Waals radii (Sb: 2.20 A Cl: 1.81 A) by 0.43 A.
As already concluded by Shindo and Okawara on the
basis of molecular weight determinations and 1H NMR
spectroscopy, (Me3SbS)2Me2SnCl2, undergoes a reversible
dissociation / ligand interchange of chlorine and sulfur
atoms in CHCl3 to give a mixture of Me3SbCl2, Me3SbS,
and (Me2SnS)3 (Eq. (2)) [3,4]. In agreement with this in-
terpretation, the 119Sn NMR spectrum (CDCl3) of
(Me3SbS)2Me2SnCl2 shows a signal at δ 133.3 with a
(2J(119Sn-S-117Sn) coupling of 191 Hz that was assigned to
(Me3SnS)3 [14]. The 13C NMR spectrum (CDCl3) shows
three signals at δ 22.7, 7.0, and 4.6 (1J(13C-119Sn) 406 Hz),
which were unambiguously assigned to Me3SbCl2, Me3SbS,
and (Me2SnS)3, respectively.
Figure 2 Experimental and iteratively fitted 119Sn MAS NMR
spectrum (149.03 MHz, νRO 8850 Hz) of (Me3SbS)2Me2SnCl2. The
centre band at δiso Ϫ288.0 is indicated by an arrow (For the tensor
analysis refer to text).
The molecular structure of (Me3SbS)2Me2SnCl2 is shown
in Figure 1; selected bond lengths and angles are given in
Table 1. The Sn atom lies across a crystallographic centre
of inversion and features a slightly distorted octahedral co-
ordination defined by a C2Cl2S2 donor set. The SnϪC,
SnϪCl and SnϪS bond lengths at 2.126(3), 2.597(1) and
Apparently, the observation of a rapid and reversible dis-
sociation / ligand interchange reaction suggests that all con-
cerned SnϪCl, SnϪS, SbϪCl, and SbϪS bonds are kine-
tically labile on the laboratory time scale and that low acti-
vation barriers exist for all reaction steps involved. In con-
trast, the thermodynamic driving force for this process
appears to be less straightforward. While the presumed in-
itial dissociation of (Me3SbS)2Me2SnCl2 into Me2SnCl2
and two molecules of Me3SbS might be attributed to an
entropy gain in solution, the reasons for the subsequent li-
gand interchange reaction between Me2SnCl2 and one mol-
ecule of Me3SbS giving one third (Me2SnS)3 and Me3SbCl2
might be tentatively explained by the Me2Sn moiety having
a slightly higher affinity to sulfur than the Me3Sb moieties.
The preference of (Me3SbS)2Me2SnCl2 in the solid-state
˚
2.746(1) A, respectively, compare best with those of
˚
Me2SnCl2·2dmtu (2.122(5), 2.616(1) and 2.729(1) A;
dmtu ϭ 1,3-dimethylthiourea [6]) and Me2SnCl2·2pyth
˚
(2.099(9), 2.623(2) and 2.729(2) A, pyth ϭ 2(1H)-pyridine-
thione [7]).The 119Sn MAS NMR spectrum of
(Me3SbS)2Me2SnCl2 is consistent with a hexacoordinated
Sn atom and shows a signal at δiso Ϫ288.0 with an ac-
companying set of spinning sidebands indicative of a large
shielding anisotropy (SA), which were used to perform a
tensor analysis according to the method of Herzfeld and
Berger [8]. The tensor components of the shielding aniso-
tropy σ11, σ22 and σ33 were determined as Ϫ54, 83 and
835 ppm; the spectrum is shown in Figure 2. Thus, the an-
isotropy ζ and symmetry η amount to 547 ppm and 0.25,
Z. Anorg. Allg. Chem. 2003, 629, 1508Ϫ1510
zaac.wiley-vch.de
 2003 WILEY-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim
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J. Beckmann, D. Dakternieks, A. Duthie, R. C. Foitzik
out with anisotropic displacement parameters applied to all non-
hydrogen atoms. Hydrogen atoms were included in geometrically
calculated positions using a riding model and were refined iso-
tropically. The weighting scheme employed was of the type w ϭ
might be attributed to the maximum energy gain associated
with the hypercoodination of the Sn and Sb atoms.
2
2
2
[σ2(F0 ) ϩ (0.0319 P)2 ϩ 0.3605 P]Ϫ1 where P ϭ (F0 ϩ 2 Fc ) / 3.
R1 ϭ 0.0207 for 2048 [I>2σ(I)] reflections and wR2 ϭ 0.0567 for
2173 independent reflections; GooF ϭ 1.090. The max. and min.
Experimental
(Me2SnS)3 was prepared according to a literature procedure [15].
Me3SbCl2 was purchased from Aldrich. NMR spectra were ob-
tained using a Jeol Eclipse Plus 400 spectrometer (at 399.78 Mz
(1H), 100.54 (13C) and 149.05 (119Sn)) and were referenced against
SiMe4 and SnMe4. The solid-state NMR spectra were measured
using the same instrument equipped with a 4 mm MAS probe and
adamantane (δ 38.6 / 29.5) and c-Hex4Sn (δ Ϫ97.35) as secondary
references. The 119Sn MAS NMR spectra were obtained using cross
polarization (contact time 5 ms, recycle delay 40s). The isotropic
chemical shifts δiso were determined by comparison of two acqui-
sitions measured at sufficiently different spinning frequencies. The
tensor analyses were performed using the method of Herzfeld and
Berger[8] implemented in DmFit 2002 [16]. The definitions used:
δiso (ppm) ϭ Ϫσiso ϭ Ϫ(σ11ϩσ22ϩσ33) / 3; ζ (ppm) ϭ σ33Ϫσiso and
η ϭ Ησ22Ϫσ11Η/Ησ33ϪσisoΗ where σ11, σ22 and σ33 (ppm) are the prin-
cipal tensor components of the shielding anisotropy (SA), defined
as follows Ησ33ϪσisoΗ>Ησ11ϪσisoΗ>Ησ22ϪσisoΗ.
residual electron densities were 0.447 / Ϫ0.611 e AϪ3. Crystallo-
˚
graphic data (excluding structure factors) have been deposited at
the Cambridge Crystallographic Data Centre as supplementary
publication no CCDC 208109. Copies of the data can be obtained,
free of charge, on application to CCDC, 12 Union Road, Cam-
bridge CB2 1EZ, UK (Fax: ϩ 44-(0)12 23-33 60 33 or e-mail:
deposit@ccdc.cam.ac.uk).
Acknowledgement. The Australian Research Council (ARC) is
thanked for financial support. Dr. Jonathan White (Melbourne
University) is gratefully acknowledged for the X-ray crystallogra-
phy data collection.
References
[1] K. Moedritzer, J. R. Van Wazer, Inorg. Chem. 1964, 3, 943.
[2] J. Beckmann, D. Dakternieks, A. Duthie, C. Jones, K. Jurk-
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Synthesis of (Me3SbS)2Me2SnCl2. A mixture of Me3SbCl2 (713 mg,
3.00 mmol) and (Me2SnS)3 (543 mg, 1.00 mmol) in methanol
(30 mL) was heated for 15 min at 50 °C to give a clear solution.
Cooling at Ϫ10 °C afforded large crystals of (Me3SbS)2Me2SnCl2
(840 mg, 1.36 mmol, 91 %; mp. 139.8-140.0 °C, Lit. 147.0-
147.5 °C [3]).
Anal. Calcd. for C8H24Cl2S2Sb2Sn (617.57): C, 15.56; H, 3.92.
Found C, 15.45; H, 3.99 %.
1H NMR (CDCl3) δ: 2.36 (3H; Me3SbCl2), 1.55 (3H; Me3SbS), 0.87 (2H,
2J(1H-C-119Sn) 62 Hz; (Me2SnS)3) (Identical to the reported 1H NMR spec-
trum within 0.01 ppm [3])
[8] J. Herzfeld, X. Chen in Encyclopedia of Nuclear Magnetic Res-
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[9] T. P. Lockhart, W. F. Manders, J. J. Zuckerman, J. Am. Chem.
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Crystallography
Single crystals of (Me3SbS)2Me2SnCl2 suitable for X-ray crystal-
lography were obtained by slow evaporation of a methanol solu-
[10] T. P. Lockhart, W. F. Manders, Inorg. Chem. 1986, 25, 892.
[11] T. P. Lockhart, W. F. Manders, J. Am. Chem. Soc. 1987, 109,
7015.
tion. Data and structure solution at
T
ϭ
293(2) K:
C8H24Cl2S2Sb2Sn, Mr ϭ 617.57, monoclinic, P1 21/n, crystal di-
[12] U. Kolb, M. Beuter, M. Dräger, Inorg. Chem. 1994, 33, 4522.
[13] J. Pebler, F. Weller, K. Dehnicke, Z. Anorg. Allg. Chem. 1982,
492, 139.
[14] A. Blecher, B. Mathiasch, T. N. Mitchell, J. Organomet. Chem.
1980, 184, 175.
mensions: 0.20 ϫ 0.30 ϫ 0.40 mm3, a ϭ 9.2887(5), b ϭ 10.0768(6),
3
˚
˚
c ϭ 10.2982(6) A, β ϭ 98.7850(10)°, V ϭ 952.61(9) A , Z ϭ 2,
ρcalcd ϭ 2.153 Mg mϪ3, F(000) ϭ 580, µ ϭ 4.593 mmϪ1. Intensity
data were collected on Bruker SMART Apex CCD diffractometer
fitted with Mo-Kα radiation (graphite crystal monochromator, λ ϭ
[15] H. Schumann, Z. Anorg. Allg. Chem. 1967, 354, 192.
˚
´
0.71073 A) to a maximum of θmax ϭ 27.49° via ω scans (complete-
[16] D. Massiot, F. Fayon, M. Capron, I. King, S. Le Calve, B.
ness 99.5 % to θmax). Data were reduced and corrected for absorp-
tion using the programs SAINT and SADABS [17]. The structure
was solved by direct methods and difference Fourier synthesis using
SHELX-97 implemented in the program WinGX 2002 [18]. Full-
matrix least-squares refinement on F2, using all data, was carried
Alonso, J.-O. Durand, B. Bujoli, Z. Gan, G. Hoatson, Mag.
Res. Chem. 2002, 40, 70.
[17] SMART, SAINT and SADABS, Siemens Analytical X-ray In-
struments Inc., Madison, Wisconsin USA, 1999.
[18] L. J. Farrugia, J. Appl. Cryst. 1997, 20, 565.
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