A sterically congested aryltrimethylstannane - Synthesis, reactivity, transmetalation and CH-π interaction

Article abstract of DOI:10.1016/j.ica.2008.04.003

The synthesis of a novel sterically congested tetraorganotin compound, (4-tert-butyl-2,6-dimesitylphenyl)trimethylstannane (1), is reported and its reactivity with special focus on transmetalation studied. The reaction of compound 1 with reagents such as HgCl₂, BiCl₃ and HOTf gave (4-tert-butyl-2,6-dimesitylphenyl)dimethyltin chloride (2) and (4-tert-butyl-2,6-dimesitylphenyl)dimethyltin triflate (3), respectively, as a result of selective tin-methyl bond cleavage. Less bulky aryltrimethyltin derivatives react with BiCl₃ to give both tin-methyl and tin-aryl bond cleavage. Hydrolysis of compound 3 proceeds slowly to give bis-(4-tert-butyl-2,6-dimesitylphenyl)dimethyl stannoxane (5) via the intermediate (4-tert-butyl-2,6-dimesitylphenyl)dimethyltin hydroxide (4). All terphenyldimethyltin derivatives that were characterized by single crystal X-ray diffraction analysis show C-H?π interactions. Based on these results, the optimum C-H?π distance (C?centroid_aryl distance) is suggested to be in the range 3.4 and 3.5 A?.

Full text of DOI:10.1016/j.ica.2008.04.003

Inorganica Chimica Acta 362 (2009) 745–752
Contents lists available at ScienceDirect
Inorganica Chimica Acta
journal homepage: www.elsevier.com/locate/ica
A sterically congested aryltrimethylstannane – Synthesis, reactivity,
transmetalation and CH–p interaction
b
b
Michael Mehring a, , Christof Nolde , Markus Schürmann
*
a Technische Universität Chemnitz, Institut für Chemie, Koordinationschemie, Straße der Nationen 62, D-09111 Chemnitz, Germany
b Universität Dortmund, Lehrstuhl für Anorganische Chemie II, Otto-Hahn-Str. 6, D-44221 Dortmund, Germany
a r t i c l e i n f o
a b s t r a c t
Article history:
The synthesis of a novel sterically congested tetraorganotin compound, (4-tert-butyl-2,6-dimesitylphe-
nyl)trimethylstannane (1), is reported and its reactivity with special focus on transmetalation studied.
The reaction of compound 1 with reagents such as HgCl2, BiCl3 and HOTf gave (4-tert-butyl-2,6-dimesi-
tylphenyl)dimethyltin chloride (2) and (4-tert-butyl-2,6-dimesitylphenyl)dimethyltin triflate (3), respec-
tively, as a result of selective tin–methyl bond cleavage. Less bulky aryltrimethyltin derivatives react with
BiCl3 to give both tin–methyl and tin–aryl bond cleavage. Hydrolysis of compound 3 proceeds slowly to
give bis-(4-tert-butyl-2,6-dimesitylphenyl)dimethyl stannoxane (5) via the intermediate (4-tert-butyl-
2,6-dimesitylphenyl)dimethyltin hydroxide (4). All terphenyldimethyltin derivatives that were charac-
terized by single crystal X-ray diffraction analysis show C–Hꢀ ꢀ ꢀp interactions. Based on these results,
the optimum C–Hꢀ ꢀ ꢀp distance (Cꢀ ꢀ ꢀcentroidaryl distance) is suggested to be in the range 3.4 and 3.5 Å.
Ó 2008 Elsevier B.V. All rights reserved.
Received 31 December 2007
Received in revised form 27 March 2008
Accepted 2 April 2008
Available online 8 April 2008
Dedicated to Professor Dr. Bernhard Lippert
Keywords:
Organotin chemistry
Bismuth
Transmetalation
Sn–C bond cleavage
C–Hꢀ ꢀ ꢀp interaction
Terphenyl ligand
1. Introduction
when organotin compounds are used as reagents for transmetala-
tion in organometallic main group chemistry. Several organome-
Organotin compounds have been intensively studied and have
found widespread use in organic synthesis [1]. The most promi-
nent examples include esterification and transesterification using
diorganotin compounds [2,3], hydride transfer reactions using tri-
organotin hydrides [4] and C–C bond coupling using tri- and
tetraorganotin compounds in the presence of metal catalysts [5].
The latter reaction which is called Stille coupling is well established
for aryl group transfer reactions using aryltrimethylstannanes in
the presence of diverse Pd catalysts [6]. However, a catalyst is
not always needed for C–C coupling reactions. For example, start-
ing from aroyl chlorides even aryltrimethylstannanes serve as re-
agents for a simple and selective synthesis of asymmetric diaryl
ketones which are otherwise difficult to prepare [7]. The method
makes use of the exceptional leaving group capacity of the trimeth-
ylstannyl cation. In contrast, selective methyl group transfer under
mild reaction conditions starting from organotin reagents is less
common and usually affords the activation of the tin–methyl bond
as for instance by catalysis or hypercoordination [8]. However, in
the presence of both tin–alkyl and tin–aryl bonds in the organotin
reagent selective tin–methyl bond cleavage is rarely observed and
the tin–aryl bond is cleaved [3,9]. The same result is observed
tallic arylboron, arylgallium and arylaluminium compounds were
prepared by aryl group transfer starting from aryltrialkylstannanes
[10,11]. Transmetalation with alkyl, allyl or vinyl group transfer is
less common but was observed occasionally [11–13]. A prominent
example is the preparation of bismabenzene starting from 1,1-di-
n-butyl-1-stannacyclo-1,4-hexadiene and bismuth trichloride [14].
We are interested in synthetic strategies towards organometal-
lic compounds of heavy main group elements and started to inves-
tigate the potential of aryltrimethylstannanes as transmetalation
reagents for bismuth halides including the sterically congested
(4-tert-butyl-2,6-dimesitylphenyl)trimethylstannane (1). Since
the discovery of the remarkable potential of bulky terphenyl li-
gands to stabilise unusual coordination numbers and oxidation
states an enormous variety of otherwise unstable organotin com-
pounds was reported [15]. Main emphasis is given to compounds
of low valency including metal clusters, whereas studies on
tetraorganotin(IV) compounds were rarely reported. However,
the first report on terphenyl substituted trimethlyltin compounds
dates back to 1964 when Seyferth et al. reported the synthesis of
2-iodo-20-trimethlytin-octaphenyl-biphenyl starting from 1-iodo-
2-trimethyltin-tetraphenylbenzene using harsh reaction condi-
tions (Scheme 1) [16]. The same product was obtained by the
reaction of 1,2-iodo-tetraphenylbenzene with 1,2-bis-trimethyl-
tin-tetraphenylbenzene. The latter was also used as a starting
* Corresponding author. Fax: +49 371 531 21219.
E-mail address: michael.mehring@chemie.tu-chemnitz.de (M. Mehring).
0020-1693/$ - see front matter Ó 2008 Elsevier B.V. All rights reserved.
doi:10.1016/j.ica.2008.04.003

746
M. Mehring et al. / Inorganica Chimica Acta 362 (2009) 745–752
repeating the initial frames at the end of data collection. Analyzing
the duplicate reflections there was no indication for any decay. The
structures were solved by direct methods using SHELXS97 [19] and
successive difference Fourier syntheses. Refinement applied full-
matrix least-squares methods using SHELXL97 [20]. The H atoms
were placed in the geometrically calculated positions using a rid-
ing model with Uiso constrained at 1.2 times Ueq for non-methyl
and 1.5 times Ueq for methyl groups of the carrier C atom.
2.3. Synthesis
2.3.1. (4-tert-Butyl-2,6-dimesitylphenyl)trimethylstannane (1)
Scheme 1.
A THF solution of 4-tert-butyl-2,6-dimesitylphenyl magnesium
bromide, prepared from 9.0 g (20 mmol) 1-bromo-2,6-dimesityl-
4-tert-butylbenzene and 2.0 g (80 mmol) magnesium in 60 ml
THF, was added dropwise within 30 min to a THF solution
(100 ml) of 5.0 g (25 mmol) Me3SnCl. The reaction mixture was
heated at reflux for 3 h. The solvent was removed under vacuo
and the residue dissolved in 50 ml Et2O. After the addition of an
aqueous KF solution, the solid formed was filtered off and the or-
ganic phase was separated and dried with MgSO4. The solvent
was removed under vacuo and the residue crystallized twice from
hexane to give 5.2 g (50% referred to 1-bromo-2,6-dimesityl-4-tert-
butylbenzene) of compound 1 as a colourless solid. Single crystals
suitable for X-ray diffraction analysis were obtained by crystallisa-
tion from n-heptane/Et2O by slow evaporation of the solvent.
Anal. Calc. for C31H42Sn (533.38): C, 69.8; H, 7.9. Found: C, 70.0;
7.9%. Mp 163–165 °C. 1H NMR (400.1 MHz, CDCl3): d ꢁ0.60 (s,
2J(1H–117/119Sn) = 53/55 Hz, 9H, Sn–CH3); 1.26 (s, 9H, CH3); 1.96
(s, 12H, CH3); 2.32 (s, 6H, CH3); 6.92 (s, 4H, Haryl); 6.98 (s, 2H, Haryl).
13C{1H} NMR (100.6 MHz, CDCl3): d ꢁ7.4 (1J(13C–117/119Sn) = 325/
341 Hz, Sn–CH3); 20.9 (CH3); 21.1 (CH3); 31.3 (CH3); 34.6 (Cq);
124.5, 128.0 (2ꢂ), 136.4, 136.5, 141.7, 148.9, 152.1 (Caryl).
material to prepare 1-trimethlytin-2-para-tolyl-tetraphenylben-
zene and 1-trimethlytin-2-meta-tolyl-tetraphenylbenzene from
para- and meta-iodo-toluene, respectively, [16]. Driving force for
these reactions is a loss of trimethyltin iodide. However, the reac-
tivity of these unsymmetrical-substituted terphenyl tin com-
pounds was not investigated.
Here, we report on the synthesis, structure and transmetalation
reaction of the terphenyl-substituted organotin(IV) compound 1
and present some of its derivatives including (4-tert-butyl-2,6-
dimesitylphenyl)dimethyltin chloride (2) and (4-tert-butyl-2,6-
dimesitylphenyl)dimethyltin triflate (3). Both the compounds were
obtained upon selective tin–methyl bond cleavage from compound
1.
2. Experimental
2.1. General procedures and instrumentation
The commercially available starting materials Me3SnCl, Me4Sn,
HgCl2, CF3SO3H (Aldrich), and BiCl3 (Lancaster) were used as re-
ceived. Solvents were distilled from appropriate drying agents
prior to use. 4-tert-Butyl-2,6-dimesitylphenyl magnesium bromide
[17], PhSnMe3, ortho-MeO–C6H4SnMe3 and ortho-Me–C6H4SnMe3
were prepared according to the literature procedures [18]. All the
reactions were carried out under inert atmosphere by using stan-
dard vacuum-line and Schlenk-type techniques. Elemental analy-
ses were performed on a LECO CHNS 932 instrument. 1H, 13C, 31P
and 119Sn NMR spectra in solution were recorded at 200.1 MHz
119Sn{1H} NMR (111.9 MHz, CH2Cl2/D2O-cap.):
d
ꢁ51.3
(1J(119Sn–13C) = 341 Hz). IR (KBr-pellet, cmꢁ1): 271 w, 293 w, 348
w, 524 vst, 551 m, 665 w, 717 st, 737 m, 773 vst, 848 vst, 882 m,
933 w br, 1011 m, 1031 m, 1045 m, 1112 m, 1172 m, 1182 m,
1200 w, 1244 w, 1361 st, 1376 st, 1434 st, 1480 st, 1539 m, 1555
m, 1572 m, 1585 st, 1612 st, 1720 w, 1776 w, 2349 w, 2729 m,
2861 vst, 2914 vst, 2962 vst.
2.3.2. (4-tert-Butyl-2,6-dimesitylphenyl)dimethyltin chloride (2)
To a suspension of 1.13 g (3.58 mmol) BiCl3 in 100 ml THF was
added 1.02 g (1.19 mmol) 1 and the reaction mixture was heated
3 h at reflux. The solid material was filtered off and the solvent re-
moved in vacuo to give quantitatively compound 2 as a colourless
solid. Single crystals suitable for X-ray diffraction analysis were ob-
tained by crystallisation from toluene/CH2Cl2 by slow evaporation
of the solvent.
Anal. Calc. for C30H39ClSn (553.79): C, 65.1; H, 7.1. Found: C,
64.8; 7.1%. Mp 175–178 °C. 1H NMR (200.1 MHz, CDCl3): d ꢁ0.22
(s, 2J(1H–117/119Sn) = 56/58 Hz, 6H, Sn–CH3); 1.29 (s, 9H, CH3);
2.03 (s, 12H, CH3); 2.33 (s, 6H, CH3); 6.96 (s, 4H, Haryl); 7.10 (s,
2H, Haryl). 13C{1H} NMR (100.6 MHz, CDCl3): d ꢁ0.2 (Sn–CH3);
21.0 (CH3); 30.9 (CH3); 31.2 (CH3); 34.8 (Cq); 125.3, 128.4 (2ꢂ),
136.6, 137.3, 140.1, 148.8, 154.3 (Caryl). 119Sn{1H} NMR
(111.9 MHz, CH2Cl2/D2O-cap.): d 81.8. IR (KBr-pellet, cmꢁ1): 272
w, 294 w, 330 st, 450 w, 524 m, 583 m, 552 m, 657 w, 722 m,
737 m, 750 m, 766 m, 793 m, 848 vst, 883 m, 925 w, 1047 m,
1114 m, 1173 m, 1201 w, 1245 st, 1362 m, 1379 m, 1439
m, 1479 m, 1542 m, 1584 m, 1612 m, 1722 w, 1777 w, 2733 m,
2862 st, 2915 st, 2961 vst, 3555 m.
(1H), 400.1 MHz (1H), 599.8 MHz (1H), 100.6 MHz
(
13C),
111.9 MHz (119Sn) and 149.2 MHz (119Sn) at room temperature
using the following spectrometers: Varian Mercury 200, Bruker
DPX 300, Bruker DRX 400 and Varian Inova 600. Chemical shifts
d are given in ppm and were referenced against Me4Si or Me4Sn,
respectively. IR spectra were obtained from a Bruker FTIR IFS
113v spectrometer. The FAB mass spectra were recorded on a Finn-
igan MAT 8230 spectrometer. Electrospray mass spectrometric
analyses (ESI-MS) were recorded in the positive mode on a Thermo-
quest-Finnigan instrument using CH3CN as the mobile phase. The
compounds were dissolved in CH3CN and then diluted with the
mobile phase to give solutions of approximate concentration
0.1 mM. The samples were introduced via a syringe pump operat-
ing at 10–20 lL/min. The capillary voltage was kept at 4.5 kV, while
the cone-skimmer voltage was varied between 50 and 180 V. The
extraction cone voltage was ꢁ5 V. The ion source temperature
was kept at 300 °C. The m/z values reported correspond to that of
the most intense peaks in the corresponding isotope pattern.
2.2. X-ray crystal structure determination
Intensity data for the colourless crystals (1–3, 5) were collected
on a Nonius KappaCCD diffractometer with graphite-monochro-
mated MoKa radiation at 173 K. Crystal decay was monitored by
2.3.3. (4-tert-Butyl-2,6-dimesitylphenyl)dimethyltin triflate (3)
A solution of 0.42 g (2.8 mmol) CF3SO3H in 25 ml toluene was
added dropwise at 0 °C to a solution of 1.50 g (2.8 mmol) 2 in

M. Mehring et al. / Inorganica Chimica Acta 362 (2009) 745–752
747
30 ml toluene. The reaction mixture was stirred at room tempera-
ture for 18 h. The solvent was removed in vacuo and the residue
dissolved in 20 ml CH2Cl2 and 20 ml n-heptane. A crystalline prod-
uct (3 ꢀ 2.5H2O) suitable for single crystal X-ray diffraction analysis
was obtained after slow evaporation of the solvent. After drying in
vacuo 1.43 g (73%) of colourless, partially dehydrated 3 was
isolated.
yield starting from Ar*MgBr and Me3SnCl. Excess Me3SnCl is re-
moved by treatment with potassium fluoride solution and subse-
quent filtration of the insoluble trimethyltin fluoride. Compound
1 was crystallised from n-heptane/Et2O as well as from acetoni-
trile/Et2O to give colourless crystals. Noteworthy, attempts to pre-
pare the corresponding aryltributyl- and aryltricyclohexylstannane
failed which we ascribe to steric reasons.
Anal. Calc. for C31H43F3O5SSn (703.44): C, 52.9; H, 6.2. Found: C,
53.5; 6.0%. Mp 172 °C. 1H NMR (400.1 MHz, CDCl3): d 0.04 (s,
2J(1H–117/119Sn) = 56/58 Hz, 6H, Sn–CH3); 1.29 (s, 9H, t-Bu); 1.78
(s, 4H, H2O); 1.98 (s, 12H, CH3); 2.32 (s, 6H, CH3); 6.96 (s, 4H, Haryl);
7.16 (s, 4J(1H–117/119Sn) = 22 Hz, 2H, Haryl). 1H NMR (400.1 MHz,
CD3CN): d ꢁ0.20 (s, 2J(1H–117/119Sn) = 68/70 Hz, 6H, Sn–CH3);
1.30 (s, 9H, t-Bu); 2.00 (s, 12H, CH3); 2.30 (s, 6H, CH3); 3.07 (s,
4H, H2O) 6.97 (s, 4H, Haryl); 7.12 (s, 4J(1H–117/119Sn) = 23 Hz, 2H,
Haryl); 3C NMR data from 1H–13C–COSY (599.8 MHz, CDCl3): d 2.0
(Sn–CH3), 21.0 (CH3), 21.4 (CH3), 31.3 (CH3), 35.6 (Cq), 126.0,
128.9 (2ꢂ), 136.0, 136.7, 138.4, 139.6, 156.1 (Caryl); 119Sn{1H}
Compound 1 was reacted with BiCl3 in THF at reflux in order to
study whether Ar*BiCl2 or MeBiCl2 is formed. A colourless precipi-
tate was observed that was soluble in DMSO-d6 and gave a single
1H NMR resonance at 1.56 ppm. Although aryl group transfer to
bismuth might be expected the 1H NMR spectrum was indicative
for the exclusive formation of MeBiCl2 [21]. Work-up of the reac-
tion mixture followed by the crystallisation of the reaction product
and subsequent characterisation of the latter including 1H, 13C and
119Sn NMR proofed the transmetalation to occur with methyl
group transfer to bismuth to give Ar*SnMe2Cl (2) quantitatively
(Scheme 2). Compound 2 crystallized from the various mixtures
of solvents (iso-PrOH/Et2O; iso-PrOH/CH2Cl2; toluene/CH2Cl2) by
slow evaporation of the solvent to give colourless crystals. The sin-
gle crystal X-ray diffraction analysis confirmed the formation of
Ar*SnMe2Cl (2). Aryl group transfer with attack at the ipso-carbon
atom in favour of alkyl group transfer is usually observed in trans-
metalation reactions. However, selective tin–alkyl bond cleavage
was previously shown to occur in some intramolecularly coordi-
nated organotin compounds [22,23] and in sterically demanding
aryltrialkylstannanes such as 2,20-bis(trimethylstannyl)-1,10-
binaphthyl upon reaction with BCl3 [13].
NMR (111.9 MHz, CH2Cl2/D2O-cap.):
d
168.8; 119Sn{1H} NMR
(111.9 MHz, toluene/D2O-cap.): d 151.5; 119Sn{1H} NMR (149.2
MHz, CD3CN): d ꢁ24.3; IR (KBr-pellet, cmꢁ1): 519 w, 554 m, 579
w, 632 st, 764 st, 850 m, 884 w, 1021 vst, 1113 w, 1234 vst,
1288 vst, 1389 m, 1479 m, 1541 w, 1586 m, 1612 m, 1658 m,
2868 m, 2961 m, 3259 st br, 3414 st br; FAB-MS: m/z (%) 519
(100, M-OTf); (+)ESMS m/z (%) 560 (65, [C28H33Me2Sn + CH3CN]+),
530 (32, [C27H30MeSn + CH3CN]+), 519 (100, [C28H33Me2Sn]+), 489
(86, [C27H30MeSn]+).
2.3.4. (4-tert-Butyl-2,6-dimesitylphenyl)dimethyltin hydroxide (4)
and bis-(4-tert-butyl-2,6-dimesitylphenyl)dimethyl stannoxane (5)
To a solution of 0.50 g (5.0 mmol) Et3N in 10 ml water was
added dropwise a solution of 0.20 g (0.28 mmol) 3 in 30 ml CH2Cl2.
The reaction mixture was stirred for 2 h. The organic phase
was separated, dried with MgSO4 and the solvent removed in
vacuo. The yellow residue (0.18 g) was composed of the start-
ing material, [Et3NH]OTf and Ar*SnMe2OH (4). The following
NMR data were assigned to compound 4: 1H NMR (400.1 MHz,
CDCl3): d ꢁ1.00 (s, 2J(1H–117/119Sn) = 27 Hz, 1H, Sn–OH), ꢁ0.12
(s, 2J(1H–117/119Sn) = 56/58 Hz, 6H, Sn–CH3); 1.28 (s, 9H, t-Bu);
2.00 (s, 12H, CH3); 2.31 (s, 6H, CH3); 6.95 (s, 4H, Haryl); 7.08
(s, 4J(1H–117/119Sn) = 18 Hz, 2H, Haryl); 119Sn{1H} NMR (149.2 MHz,
CDCl3): d 37.7. The residue was dissolved in a mixture of 10 ml
CH2Cl2 and 5 ml n-hexane. Upon slow evaporation of the solvent
a crop of crystals of compound 5 suitable for single crystal X-ray
diffraction analysis was isolated. 1H NMR (400.1 MHz, CDCl3):
d ꢁ0.19 (s, 2J(1H–117/119Sn) = 59 Hz, 12 H, Sn–CH3); 1.27 (s, 18H,
t-Bu); 2.00 (s, 24H, CH3); 2.30 (s, 12H, CH3); 6.94 (s, 8H, Haryl);
7.07 (s, 4J(1H–117/119Sn) = 18 Hz, 2H, Haryl); 119Sn{1H} NMR (149.2
MHz, CDCl3): d 44.0.
In order to show that methyl group transfer is a result of the
bulkiness of the terphenyl ligand and not restricted to bismuth re-
agents compound 1 was reacted with HgCl2, iodine and CF3SO3H.
These compounds are well-known reagents for selective tin–phe-
nyl bond cleavage in compounds of the type Ph4ꢁxRxSn (x = 1–3,
R = alkyl) [1]. Surprisingly, compound 1 did not react with iodine.
Reaction with HgCl2 and CF3SO3H gave selective cleavage of the
tin–methyl bond, thus providing Ar*SnMe2Cl (2) and Ar*Sn-
Me2(OTf) (3), respectively (Scheme 3).
The latter was crystallized from heptane/CH2Cl2 by slow evapo-
ration of the solvent in the presence of moisture to give the hy-
drated aqua-complex [Ar*SnMe2(OTf)(H2O)] ꢀ 1.5 H2O (3 ꢀ 2.5H2O).
Compound 3 is stable in air in the presence of air moisture, but
the addition of Et3N and water to a CH2Cl2 solution of compound
3 gave the hydrolysis product Ar*SnMe2(OH) (4). We did not isolate
pure 4, but did obtain a mixture of compound 4, triethylammo-
nium triflate and starting material 3. Upon crystallisation from
CH2Cl2/hexane by slow evaporation of the solvent a few crystals
were obtained. Surprisingly, the single crystal structure analysis
showed that the condensation product [Ar*SnMe2]O (5) was
formed (Scheme 4). Thus, the bulky terphenyl ligand does not pre-
vent the triorganotin hydroxide from condensation. Noteworthy,
2.3.5. Transmetalation – general procedure
In a typical procedure, 0.87 g (3.6 mmol) PhSnMe3 was added to
a slurry of 1.1 g (3.6 mmol) BiCl3 in 5 ml THF. The reaction mixture
was heated at reflux for 2 h. The solvent was removed in vacuo and
3 ml CH2Cl2 was added. The solid material was filtered off and the
solution was analysed by 119Sn NMR. The reported yields are based
on the integration of the 119Sn NMR signals. Each experiment was
repeated four times.
3. Results and discussion
3.1. Synthesis and reactivity of (4-tert-butyl-2,6-dimesitylphenyl)tri-
methylstannane (1)
The synthesis of the title compound (4-tert-butyl-2,6-dimesityl-
phenyl)trimethylstannane (Ar*SnMe3, 1) was achieved with 49%
Scheme 2.

748
M. Mehring et al. / Inorganica Chimica Acta 362 (2009) 745–752
Scheme 3.
Scheme 4.
the diorganotin dihydroxide (2,6-Mes2H3C6)2Sn(OH)2 was reported
to be stabilized by both the bulky ligand and additional OH-p inter-
actions [24], thus preventing distannoxane formation.
drate of the triorganotin triflate 3 and distannoxane 5 were
determined.
Single crystals of compound 1 suitable for single crystal X-ray
diffraction analysis were obtained from n-heptane/Et2O as well
as from acetonitrile/Et2O by slow evaporation of Et2O. The com-
pound crystallizes in the space group P21/n with eight discrete
mononuclear molecules in the unit cell. The asymmetric unit con-
tains two conformations of the tetraorganotin compound, 1a and
1b. Selected bond lengths and angles are given in the caption of
Fig. 1. In conformer 1a, two methyl groups of the Me3Sn moiety
corresponding to C(31) and C(33) lie above the p-faces of the mesi-
tyl-rings and show short H3C ꢀ ꢀ ꢀ Caryl distances in the range 3.29–
4.16 Å. Thus, the C–Hꢀ ꢀ ꢀp distances of the CH3 groups to the ring
centroids (C ꢀ ꢀ ꢀ centroidaryl distance) amount to 3.59 and 3.54 Å,
respectively. These values are close to values that are ascribed to
typical attractive C–Hꢀ ꢀ ꢀp interactions with distances of approxi-
mately 3.75 Å [25]. However, the tin–carbon bond distances are
in the expected range and the coordination geometry at the tin
atoms is very close to tetrahedral without significant distortions.
For example, an average C–Sn–C angle of 109.4(2)° is observed
and the largest deviation is found for C(33)–Sn(1)–C(1) with
113.74(14)°. The values for the geometrical factors DR(#Sn(1)) =
12.3° and DR(#Sn(2)) = 7.7° are also indicative for tetrahedral coor-
dination in both conformers. The geometrical factor was originally
introduced to describe structures along the pathway tetrahedron–
trigonal bipyramid but might also be used to describe the deviation
of a tetrahedron from its ideal geometry. The position along the
pathway is given by the difference of the sums of the hypothetical
equatorial and axial angles DR (#), which is 0° for the ideal tetrahe-
dron and 90° for the trigonal bipyramid [23]. In conformer 1b, only
one methyl group is located directly above a p-face of the mesityl-
ring and the C–Hꢀ ꢀ ꢀp distance of the corresponding CH3 (C35)
group to the ring centroid amounts to 3.41 Å. The methyl groups
corresponding to C(34) and C(36) show C–Hꢀ ꢀ ꢀpcentroid distances
of 3.91 and 4.15 Å, respectively. Similar to conformer 1a, no signif-
icant distortion from a tetrahedral coordination geometry at Sn(2)
is observed. Thus, despite short H3C ꢀ ꢀ ꢀ Caryl distances free rotation
of the Me3Sn group in compound 1 is expected in solution, which is
evidenced by a single 1H NMR signal for the Me3Sn moiety in CDCl3
solution.
3.2. Transmetalation between bismuth trichloride and organotin
compounds
Similar to HgCl2, the reaction of BiCl3 with Ar*SnMe3 (1) quan-
titatively gave tin–methyl bond cleavage. Thus, it might be ex-
pected that BiCl3 shows a similar reactivity in transmetalation
reactions as it is observed for HgCl2. The latter compound is a
well-known reagent for selective tin–aryl bond cleavage for steri-
cally less demanding organotin compounds. In order to test
whether the less toxic BiCl3 might be a potential substitute for
HgCl2, we examined the reaction of BiCl3 with selected aryltri-
methylstannanes, ArSnMe3 (Ar = Ph, ortho-Me–Ph, ortho-MeO–
Ph). In contrast to the reaction with HgCl2, we did observe
tin–methyl as well as tin–aryl bond cleavage for all organotin com-
pounds. A typical reaction mixture contains 55–60% ArSnMe2Cl,
20–25% Me3SnCl and 15–20% MeSnCl3 (Scheme 5). It is worth to
note that in addition to Me3SnCl we did observe the formation of
MeSnCl3 but Me2SnCl2 was not detected in these experiments. This
is in agreement with the observation that Me3SnCl reacts with
BiCl3 to give mainly MeSnCl3 (93%) and only minor amounts of
Me2SnCl2 (7%). However, Me2SnCl2 was observed as the main prod-
uct upon the reaction of Me4Sn with equimolar amounts of BiCl3. In
contrast, neither Bu3SnCl nor Ph3SnCl, Ph4Sn or Ar*SnMe2Cl (2) did
react with BiCl3. In conclusion, BiCl3 does cleave tin–methyl and
tin–aryl bonds but a selective reaction as it is known for HgCl2
was not observed. The presented reaction of Ar*SnMe3 (1) to give
selectively Ar*SnMe2Cl (2) seems to be a rare example of selective
tin–methyl bond cleavage using BiCl3. We attribute the reverse
reactivity with a high selectivity mainly to the bulkiness of the ter-
phenyl ligand with its mesityl groups in ortho position to the tin-
bound carbon atom. Thus, attack at the ipso carbon atom becomes
less likely and tin–methyl bond cleavage is favoured. Additionally,
the stability and high solubility of Ar*SnMe2Cl (2) as well as the low
solubility of MeBiCl2 are assumed to contribute to the observed
reactivity.
3.3. Structures in the solid state
Single crystals of compound 2 suitable for single crystal X-ray
diffraction analysis were obtained from toluene/CH2Cl2 by slow
evaporation of the solvent. The compound crystallizes in the space
group P21/c with eight discrete mononuclear molecules in the unit
In course of our studies, the solid state structures of the
tetraorganotin compound 1, the triorganotin chloride 2, the hy-
Scheme 5.

M. Mehring et al. / Inorganica Chimica Acta 362 (2009) 745–752
749
Fig. 1. General view (SHELXTL) of 1 showing 30% probability displacement ellipsoids and the atom numbering scheme of molecules 1a (right) and 1b (left). Selected bond
distances [Å] and angles [°]: 1a Sn(1)–C(1) 2.172(3), Sn(1)–C(31) 2.141(4), Sn(1)–C(32) 2.139(4), Sn(1)–C(33) 2.134(4), C(31)-centroidC21–C26 3.587, C(33)-centroidC11–C16
3.541; C(1)–Sn(1)–C(31) 113.64(14), C(1)–Sn(1)–C(32) 110.01(15), C(1)–Sn(1)–C(33) 113.74(14), C(31)–Sn(1)–C(32) 105.51(17), C(31)–Sn(1)–C(33) 106.93(17), C(32)–Sn(1)–
C(33) 106.46(16); 1b Sn(2)–C(41) 2.174(3), Sn(2)–C(36) 2.138(5), Sn(2)–C(35) 2.125(4), Sn(2)–C(34) 2.121(5), C(34)-centroidC51–C56 3.918, C(35)-centroidC61–C66 3.411;
C(36)-centroidC11–C56 4.152; C(41)–Sn(2)–C(36) 111.91(17), C(41)–Sn(2)–C(35) 115.40(14), C(34)–Sn(2)–C(41) 112.54(19), C(34)–Sn(2)–C(35) 104.0(2), C(34)–Sn(2)–C(36)
108.0(3), C(35)–Sn(2)–C(36) 104.3(2).
cell. As it was observed for compound 1 the asymmetric unit con-
tains two conformers, 2a and 2b, of which 2a is shown in Fig. 2.
Similar to the Me3Sn moiety in compound 1, the Me2ClSn moiety
in compound 2 is locked in two positions and the coordination
geometry at the tin atoms might be described to be distorted tet-
rahedral although the average C–Sn–X angle (X = C, Cl) amounts
to 109.0°. The distortion is demonstrated by the values for the geo-
metrical factors DR(#Sn(1)) = 31.1° and DR(#Sn(2)) = 37.9°, which are
significantly larger than those of the tetraorganotin compound 1
[23]. Both the conformers of compound 2 contain two methyl
groups close to the p-faces of the mesityl-rings and the Cl ligands
are locked between the two bulky mesityl rings. The C–Hꢀ ꢀ ꢀp dis-
tances of the CH3 groups to the ring centroids (C ꢀ ꢀ ꢀ centroidaryl dis-
tance) in conformer 2a amount to 3.44 and 3.56 Å, and in
conformer 2b to 3.52 and 3.55 Å. These short distances might be
interpreted as a result of an attractive C–Hꢀ ꢀ ꢀp interaction. This
assumption is supported by a closer look at the C(31)/C(32)–
Sn(1)–C(1) and C(34)/C(35)–Sn(2)–C(41) bond angles, which are
in the range 116.8–119.0° and thus deviate strongly from an ideal
tetrahedral angle. Furthermore, short CH3 ꢀ ꢀ ꢀ Cl–Sn distances are
observed with C ꢀ ꢀ ꢀ Cl distances in the range 3.62–3.95 Å, which
is in the expected region reported for this type of week hydrogen
bonds [26]. Noteworthy, in conformer 2a the C ꢀ ꢀ ꢀ Cl distances
amount to 3.73 and 3.79 Å (av. 3.75 Å), respectively, and in con-
former 2b to 3.62 and 3.95 Å (av. 3.79 Å). In conclusion, compound
2 shows a balanced interplay between different types of weak
interactions leading to different conformations with the Cl ligand
locked between the mesityl rings.
Single crystals of the hydrated form of the organotin triflate 3
suitable for single crystal X-ray diffraction analysis were obtained
from heptane/CH2Cl2 by slow evaporation of the solvent. The com-
pound crystallizes in the space group Ccca with sixteen molecules
in the unit cell. As a result of coordination of a water molecule, the
coordination geometry at the tin atom is best described as trigonal
bipyramidal with three carbon-atom-based ligands occupying the
equatorial positions, and the oxygen atoms of the triflate group
and the water molecule in axial positions (Fig. 3). The O(1)–
Sn(1)–O(2) angle amounts to 176.16(10)° and the angles within
the equatorial plane amount to 122.74(14)°, 121.79(13)° and
115.32(13)° for C(1)–Sn(1)–C(31), C(1)–Sn(1)–C(33) and C(31)–
Sn(1)–C(33), respectively. Noteworthy, both methyl groups are
centred above the p-faces of the mesityl-rings and the C–Hꢀ ꢀ ꢀp dis-
tances of the CH3 groups to the ring centroids (C ꢀ ꢀ ꢀ centroidaryl dis-
tance) amount to 3.42 and 3.46 Å. These values are among the
shortest for the reported compounds in this work. However, the
bond angle C(31)–Sn(1)–C(33) of 115.32(13)° might be interpreted
to be the result of repulsion of the methyl groups from the p-ligand
face rather than attraction. Thus, it might be concluded that the
ideal C ꢀ ꢀ ꢀ centroidaryl distance of a SnCH3 group amounts to
approximately 3.4–3.5 Å.
In addition to the water molecule coordinated at the tin atom, a
water molecule (O(5), site occupation 50%) is bonded to the triflate
group via a strong hydrogen bond. The corresponding bond dis-
tance O(3)–O(5) amounts to 2.775(5) Å. As a result of additional
hydrogen bonding using the oxygen atoms O(3) and O(4) of the tri-
flate ligand and the oxygen atoms O(1) and O(5) of the water mol-
ecules, compound 3 forms an one-dimensional hydrogen-bonded
Fig. 2. General view (SHELXTL) of 2 showing 30% probability displacement ellipsoids
and the atom numbering scheme. One out of two independent molecules, 2a and
2b, of the unit cell is shown. Selected bond distances [Å] and angles [°] of 2a: Sn(1)–
C(1) 2.160(4), Sn(1)–C(31) 2.124(4), Sn(1)–C(32) 2.128(5), Sn(1)–Cl(1) 2.3643(16),
C(31)-centroidC11–C16 3.440, C(32)-centroidC21–C26 3.558; C(1)–Sn(1)–Cl(1) 106.16-
(12), C(31)–Sn(1)–C(32) 108.4(2), C(31)–Sn(1)–C(1) 117.23(17), C(32)–Sn(1)–C(1)
119.03(17), C(31)–Sn(1)–Cl(1) 101.29(15), C(1)–Sn(1)–Cl(1) 106.16(12).

750
M. Mehring et al. / Inorganica Chimica Acta 362 (2009) 745–752
group to act as good hydrogen bond acceptor. Some additional
water is found in the crystal lattice that does not form hydrogen
bonds and is partially lost upon drying. The IR spectrum shows
two absorption bands at 3259 cmꢁ1 and 3414 cmꢁ1 corresponding
to the hydrogen bonded water molecules and water trapped in the
crystal lattice.
Single crystals of distannoxane 5 suitable for single crystal
X-ray diffraction analysis were obtained from n-hexane/CH2Cl2
by slow evaporation of the solvent. The compound crystallizes in
the space group P21/c with four discrete mononuclear molecules
in the unit cell. Selected bond lengths and angles are given in the
caption of Fig. 5. The coordination geometry at tin is best described
as tetrahedral. This is nicely demonstrated by the values for the
geometrical factors DR(#Sn(1)) = 12.1° and DR(#Sn(2)) = 8.6°, which
are close to the ideal value of 0° for tetrahedral coordination
[23]. The Sn(1)–O(1)–Sn(2) angle of 127.35(13)° is comparable to
the corresponding bond angle in (Ph3Sn)2O (137.3°) [27], but devi-
ates strongly from the linear arrangement reported for the bulky
(tert-Bu3Sn)2O and [(PhCH2)3Sn]2O [28]. Noteworthy, the analogue
terphenyldimethyldisiloxane shows an O–Si–O angle of 141.9° and
a slightly increased value DR (#Si) = 15.7° [29]. Similar to the other
reported compounds, the methyl groups at tin are in proximity to
the p-faces of the mesityl-rings and the C–Hꢀ ꢀ ꢀp distances of the
CH3 groups to the ring centroids (C ꢀ ꢀ ꢀ centroidaryl distance) are
in the range 3.39–3.57 Å. (Table 1)
Fig. 3. General view (SHELXTL) of the hydrated form of 3 showing 30% probability
displacement ellipsoids and the atom numbering scheme. The position of O(5)
shows an occupation factor of 50%. Selected bond distances [Å] and angles [°]:
Sn(1)–C(1) 2.131(3), Sn(1)–C(31) 2.118(4), Sn(1)–C(33) 2.114(4), Sn(1)–O(1) 2.27-
3(3), Sn(1)–O(2) 2.351(3), C(31)-centroidC21–C26 3.416, C(33)-centroidC11–C16 3.456,
O(1)–O(40) 2.705(4), O(1)–O(50) 2.731(4), O(3)–O(5) 2.775(5); O(1)–Sn(1)–O(2)
176.16(10), C(1)–Sn(1)–O(1) 94.70(13), C(1)–Sn(1)–O(2) 88.66(12), C(1)–Sn(1)–
C(31) 122.74(14), C(1)–Sn(1)–C(33) 121.79(13), C(31)–Sn(1)–C(33) 115.32(13),
C(31)–Sn(1)–O(1) 88.55(14), C(31)–Sn(1)–O(2) 88.07(13), C(33)–Sn(1)–O(1)
90.44(14), C(33)–Sn(1)–O(2) 89.36(13).
3.4. Structures in solution
119Sn chemical shifts, 1J(119Sn–13C) and 2J(119Sn–1H) coupling
constants were shown to be sensitive measures for the elucidation
Fig. 4. View of hydrated 3 along the a-axis showing the hydrogen bond pattern that
extends in the direction of the c-axis.
Fig. 5. General view (SHELXTL) of 5 showing 30% probability displacement ellipsoids
and the atom numbering scheme. Selected bond distances [Å] and angles [°] corres-
ponding to Sn(1): Sn(1)–C(1) 2.169(4), Sn(1)–C(20) 2.139(4), Sn(1)–C(30) 2.132(4),
Sn(1)–O(1) 1.908(2), C(20)-centroidC11–C16 3.565, C(30)-centroidC21–C26 3.394; C(1)–
Sn(1)–O(1) 108.59(12), C(20)–Sn(1)–C(30) 106.64(17), C(1)–Sn(1)–C(20) 114.49(15),
C(1)–Sn(1)–C(30) 113.10(15), O(1)–Sn(1)–C(20) 106.76(14), O(1)–Sn(1)–C(30)
106.83(13).
polymer (Fig. 4). The hydrogen bond distances O(1)–O(4)
2.705(4) Å and O(1)–O(5) 2.731(4) Å are indicative for strong
hydrogen bonds, which demonstrates the capability of the triflate

M. Mehring et al. / Inorganica Chimica Acta 362 (2009) 745–752
751
Table 1
Crystallographic data for compounds 1–3 2.5H2O and 5
Compound number
1
2
3 2.5H2O
5
Empirical formula
Formula weight
Crystal system
Space group
a (Å)
C31H42Sn
533.34
monoclinic
P21/n
17.0047(2)
14.1320(3)
24.2176(3)
90.4415(3)
5819.57(13)
8
1.217
0.893
0.08 ꢂ 0.05 ꢂ 0.05
3.12–27.47
47107
C30H39ClSn
553.75
monoclinic
P21/n
18.3994(2)
16.9166(2)
18.8325(2)
99.3756(11)
5783.44(11)
8
1.272
0.990
0.10 ꢂ 0.07 ꢂ 0.07
3.26–27.49
43417
C31H39F3O3SSn 2.5H2O
712.41
orthorhombic
Ccca
22.6827(4)
38.1207(6)
16.9599(4)
C60H78OSn2
1052.60
monoclinic
P21/c
13.0633(2)
12.3163(2)
34.8121(5)
100.2137(5)
5512.21(15)
4
1.268
0.943
0.15 ꢂ 0.15 ꢂ 0.13
3.07–25.34
40713
b (Å)
c (Å)
b (°)
V (Å3)
14664.9(5)
16
1.291
Z
ucalc (g cmꢁ3
)
l (mmꢁ1
)
0.803
Crystal size (mm3)
h Range (°)
0.25 ꢂ 0.23 ꢂ 0.20
3.02–25.34
43012
6695
0.054
Reflection collected
Independent reflection
Rint
13128
0.026
12840
0.037
10041
0.036
Completeness to 2h (%)
Goodness-of-fit (F2)
R1 [I > 2r(I)]
98.4
1.023
0.0449
96.7
0.985
0.0504
99.5
0.838
0.0348
99.5
0.970
0.0363
wR2 (all data)
0.1147
0.812/ꢁ0.658
0.1247
1.216/ꢁ1.410
0.0686
0.385/ꢁ0.352
0.0863
0.545/ꢁ0.588
Largest differrence in peak and hole (e Åꢁ3
)
of coordination numbers and geometries of organotin compounds
with similar substituent patterns [30–32]. High field shift of the
119Sn NMR signal and an increase of the 2J(119Sn–1H) coupling con-
stants are usually indicative for an increase in the coordination
number. The 119Sn and 1H NMR data for compounds 1–5 are listed
in Table 2. The 119Sn NMR as well as the 1H NMR signal of the
SnCH3 group in the bulky Ar*SnMe3 (1) (d 119Sn ꢁ51.3, d 1H
ꢁ0.60) is shifted to a higher field in comparison to PhSnMe3 (d
119Sn ꢁ29.4, d 1H 0.28). However, this is rather a result of an
increasing coordination number at tin but a result of the aniso-
tropic ring current effect of the mesityl groups. The SnCH3 groups
are close to the p-faces of the mesityl rings and thus are highly
shielded. This phenomenon is observed for all of reported
compounds.
a
solvent-dependent coordination behaviour. In CDCl3,
a
2J(119Sn–1H) coupling constant of 58 Hz is observed which in-
creases to 70 Hz in CD3CN. The latter value is in agreement with
an CH3–Sn–CH3 angle of 120° and indicates pentacoordination at
the tin atom, whereas the former is indicative for tetracoordina-
tion. The change of coordination is also demonstrated by 119Sn
NMR. The 119Sn chemical shift of compound 3 in non-coordinating
solvents is found between 150 and 170 ppm, whereas in CD3CN a
high-field shift to ꢁ24.3 ppm is observed as a result of the coordi-
nation of acetonitrile. The strong coordination of acetonitrile is
demonstrated by electrospray ionization mass spectrometry using
CH3CN as a solvent. In addition to the peak assigned to [MꢁOTf]+,
the acetonitrile adduct [MꢁOTf+CH3CN]+ is observed as a promi-
nent peak.
In this work, the 2J(119Sn–1H) coupling constant is better suited
to study the coordination at the tin atom in solution. According to
Lockhart and Manders, the CH3–Sn–CH3 angle in methyltin com-
pounds can be calculated according to the empirical formula
h = 0.0161 (2J)2 ꢁ 1.32(2J) + 133.4 [32]. In agreement with the solid
state structural analysis, the 2J(119Sn–1H) coupling constant of
55 Hz for compound 1 is in agreement with a tetrahedral coordina-
tion. Similar coupling constants are observed for compounds 2, 4
and 5, and thus are indicative for tetrahedral coordination at the
tin atoms similar to 1. In contrast, the organotin triflate 3 shows
4. Conclusion
We have prepared a novel sterically congested tetraorganotin
compound, (4-tert-butyl-2,6-dimesitylphenyl)trimethylstannane
(1), and its reactivity is studied with a special focus on trans-
metalation. The results demonstrate that compound 1 is not
suitable to act as a transfer reagent for the bulky terphenyl li-
gand, but is suitable for a methyl group transfer. Selective tin–
methyl bond cleavage with reagents such as HOTf, HgCl2 and
BiCl3 was observed. It is well known that aryltrimethyltin com-
pounds bearing less bulky aryl ligands show a reverse selectivity
in reactions with HOTf and HgCl2. However, we have shown that
in the case of BiCl3 the cleavage of both Sn–methyl and Sn–aryl
bonds results for compounds such as PhSnMe3. Thus, the reac-
tion of Ar*SnMe3 (1) to give selectively Ar*SnMe2Cl (2) upon
reaction with BiCl3 seems to be a rare example of selective
tin–methyl bond cleavage in favour of tin–aryl bond cleavage.
The reactivity is assumed to be partially a result of the low sol-
ubility of MeBiCl2, but the major reason for the selectivity is as-
cribed to a steric effect by the terphenyl ligand. Additionally,
both methyl groups in the reaction product 2 are close to the
p-faces of the mesityl-rings with an average C–Hꢀ ꢀ ꢀp ring cen-
troid distance of 3.52 Å and thus contribute to the stabilisation
as well as to the high solubility of the reaction product 2. This
is assumed to additionally favour the selective tin–methyl bond
cleavage in 1.
Table 2
Selected 119Sn and 1H NMR data of compounds 1–5a
Compound
d
119Sn/ppm
d1H (CH3)/ppm
1J (1H–119Sn)/Hz
PhSnMe3
ꢁ29.4 [30]
ꢁ51.3b
0.28 [33]
ꢁ0.60
56 [33]
55
58
Ar*SnMe3 (1)
Ar*SnMe2Cl (2)
81.8b
ꢁ0.22
Ar*SnMe2(OTf) (3)
168.8b
151.1c
ꢁ24.3d
37.7
44.0
0.04
58
ꢁ0.20d
70d
Ar*SnMe2(OH) (4)
(Ar*SnMe2)2O (5)
ꢁ0.12
60
59
ꢁ0.19
a
1H and 119Sn NMR spectra were recorded from CDCl3 solution if not otherwise
stated.
b
c
CH2Cl2/D2O capillary.
Toluene/D2O capillary.
CD3CN.
d

752
M. Mehring et al. / Inorganica Chimica Acta 362 (2009) 745–752
[15] Selected examples (a) B.E. Eichler, P.P. Power, Inorg. Chem. 39 (2000) 5444;
5. Supplementary material
(b) L.H. Pu, A.D. Phillips, A.F. Richards, M. Stender, R.S. Simons, M.M. Olmstead,
P.P. Power, J. Am. Chem. Soc. 125 (2003) 11626;
CCDC 670709–670711 and 670712 contain the supplementary
crystallographic data for 1–3 and 5. These data can be obtained free
of charge from The Cambridge Crystallographic Data Centre via
www.ccdc.cam.ac.uk/data_request/cif.
(c) A.F. Richards, B.E. Eichler, M. Brynda, M.M. Olmstead, P.P. Power, Angew.
Chem. 117 (2005) 2602;
(d) B.E. Eichler, B.L. Philips, P.P. Power, M.P. Augustine, Inorg. Chem. 39 (2000)
5450;
(e) A.F. Richards, H. Hope, P.R. Power, Angew. Chem., Int. Ed. 42 (2003) 4071;
(f) A.C. Filippou, A.I. Philippopoulos, G. Schnakenburg, Organometallics 22
(2003) 3339;
(g) C. Stanciu, A.F. Richards, M. Stender, M.M. Olmstead, P.P. Power,
Polyhedron 25 (2006) 477;
Acknowledgements
(h) C. Stanciu, A.F. Richards, J.C. Fettinger, M. Brynda, P.P. Power, J. Organomet.
Chem. 691 (2006) 2540;
(i) M. Saito, N. Tokitoh, R. Okazaki, J. Am. Chem. Soc. 126 (2004) 15572;
(j) W. Setaka, K. Hirai, H. Tomioka, K. Sakamoto, M. Kira, J. Am. Chem. Soc. 126
(2004) 2696;
(k) E. Rivard, J. Steiner, J.C. Fettinger, J.R. Giuliani, M.P. Augustine, P.P. Power,
Chem. Commun. (2007) 4919;
(l) E. Rivard, R.C. Fischer, R. Wolf, Y. Peng, W.A. Merrill, N.D. Schley, Z.L. Zhu, L.
Pu, J.C. Fettinger, S.J. Teat, I. Nowik, R.H. Herber, N. Takagi, S. Nagase, P.P.
Power, J. Am. Chem. Soc. 129 (2007) 16197;
Financial support was provided by the Deutsche Forschungs-
gemeinschaft and the Fonds der Chemischen Industrie. M.M. is grate-
ful to Professor Dr. K. Jurkschat (Universität Dortmund) for the
support of this scientific work, and to Professor Dr. Bernhard Lip-
pert (Universität Dortmund) for fruitful cooperation concerning
education.
References
(m) M. Saito, H. Hashimoto, T. Tajima, M. Ikeda, J. Organomet. Chem. 692
(2007) 2729;
[1] A.G. Davies, Organotin Chemistry, Wiley-Vch, Weinheim, 2004.
[2] (a) J. Otera, Acc. Chem. Res. 37 (2004) 288;
(n) T. Tajima, N. Takeda, T. Sasamori, N. Tokitoh, Organometallics 25 (2006)
3552;
(b) Z.H. Peng, A. Orita, D. An, J. Otera, Tetrahedron Lett. 46 (2005) 3187.
[3] M. Mehring, M. Schürmann, I. Paulus, D. Horn, K. Jurkschat, A. Orita, J. Otera, D.
Dakternieks, A. Duthie, J. Organomet. Chem. 574 (1999) 176.
[4] W.C. Carland, C.H. Schiesser, in: Z. Rappoport (Ed.), The Chemistry of Organic
Germanium, Tin and Lead Compounds, John Wiley & Sons Ltd, Chichester,
2002, p. 1401.
[5] (a) E. Fouquet, in: Z. Rappoport (Ed.), The Chemistry of Organic Germanium,
Tin and Lead Compounds, John Wiley & Sons Ltd, Chichester, 2002, p. 1335;
(b) B. Jousseaume, M. Pereyre, in: P.J. Smith (Ed.), Chemistry of Tin, Blackie
Academic & Professional, London, 1998, p. 290.
[6] J.K. Stille, Angew. Chem., Int. Ed. 25 (1986) 508.
[7] G.F. Silbestri, R.B. Masson, M.T. Lockhart, A.B. Chopa, J. Organomet. Chem. 691
(2006) 1520.
[8] (a) M. Huiban, A. Huet, L. Barre, F. Sobrio, E. Fouquet, C. Perrio, Chem. Commun.
(2006) 97;
(b) E. Vedejs, A.R. Haight, W.O. Moss, J. Am. Chem. Soc. 114 (1992) 6556.
[9] (a) M. Schulte, M. Mehring, I. Paulus, M. Schürmann, K. Jurkschat, D.
Dakternieks, A. Duthie, A. Orita, J. Otera, Phosphorus, Sulfur Silicon Relat.
Elem. 151 (1999) 201;
(o) T. Tajima, N. Takeda, T. Sasamori, N. Tokitoh, Eur. J. Inorg. Chem. 21 (2005)
4291.
[16] D. Seyferth, C. Sarafidis, A.B. Evnin, J. Organomet. Chem. (1964) 417.
[17] C. Nolde, M. Schürmann, M. Mehring, Z. Anorg. Allg. Chem. 633 (2007)
142.
[18] C. Eaborn, H.L. Hornfeld, D.R.M. Walton, J. Organomet. Chem. 10 (1967) 529.
[19] G.M. Sheldrick, Acta Crystallogr., Sect. A 46 (1990) 467.
[20] G.M. Sheldrick, University of Göttingen, 1997.
[21] H. Althaus, H.J. Breunig, E. Lork, Organometallics 20 (2001) 586.
[22] (a) J. Jastrzebski, G. van Koten, Adv. Organomet. Chem. 35 (1993) 241;
(b) B. Jousseaume, P. Villeneuve, J. Chem. Soc., Chem. Commun. (1987) 513;
(c) H. Weichmann, B. Rensch, Z. Anorg. Allg. Chem. 503 (1983) 106;
(d) H. Weichmann, A. Tzschach, J. Prakt. Chem. 318 (1976) 87.
[23] U. Kolb, M. Dräger, B. Jousseaume, Organometallics 10 (1991) 2737.
[24] L.H. Pu, N.J. Hardman, P.P. Power, Organometallics 20 (2001) 5105.
[25] G.R. Desiraju, T. Steiner, The Weak Hydrogen Bond in Structural Chemistry and
Biology, Oxford University Press, Oxford, 1999.
[26] J.A. van den Berg, K.R. Seddon, Cryst. Growth Des. 3 (2003) 643.
[27] C. Glidewell, D.C. Liles, Acta Crystallogr., Sect. B 34 (1978) 129.
[28] (a) C. Glidewell, D.C. Liles, J. Chem. Soc., Chem. Commun. (1979) 93;
(b) S. Kerschl, B. Wrackmeyer, D. Männig, H. Nöth, R. Staudigl, Z. Naturforsch.
B: Chem. Sci. 42 (1987) 387.
(b) V. Chandrasekhar, K. Gopal, P. Sasikumar, R. Thirumoorthi, Coord. Chem.
Rev. 249 (2005) 1745.
[10] (a) J.J. Eisch, B.W. Kotowicz, Eur. J. Inorg. Chem. (1998) 761;
(b) J.D. Hoefelmeyer, D.L. Brode, F.P. Gabbai, Organometallics 20 (2001) 5653;
(c) M. Tschinkl, J.D. Hoefelmeyer, T.M. Cocker, R.E. Bachman, F.P. Gabbai,
Organometallics 19 (2000) 1826;
[29] R. Pietschnig, M. Merz, Organometallics 23 (2004) 1373.
[30] B. Wrackmeyer, in: G.A. Webb (Ed.), Annual Reports on NMR Spectroscopy,
vol. 16, Academic Press, London, 1985, p. 291.
(d) M. Tschinkl, R.E. Bachman, F.P. Gabbai, Chem. Commun. (1999) 1367.
[11] (a) J.J. Eisch, K. Mackenzie, H. Windisch, C. Krüger, Eur. J. Inorg. Chem. (1999)
153;
(b) H. Nöth, H. Vahrenkamp, J. Organomet. Chem. 11 (1968) 399.
[12] W.P. Neumann, R. Köster, R. Schick, Angew. Chem., Int. Ed. 3 (1964) 385.
[13] B. Schilling, V. Kaiser, D.E. Kaufmann, Chem. Ber. 130 (1997) 923.
[14] A.J. Ashe, Acc. Chem. Res. 11 (1978) 153.
[31] (a) T.P. Lockhart, F. Davidson, Organometallics 6 (1987) 2471;
(b) T.P. Lockhart, J.C. Calabrese, F. Davidson, Organometallics 6 (1987) 2479;
(c) M. Mehring, M. Schürmann, K. Jurkschat, Organometallics 17 (1998) 1227.
and ref. cited.
[32] T.P. Lockhart, W.F. Manders, Inorg. Chem. 25 (1986) 892.
[33] M. Bullpitt, W. Kitching, W. Adcock, D. Doddrell, J. Organomet. Chem. 116
(1976) 161.