Cyclohexasilanes with exocyclic organogermanium, -tin or -lead groups

Article abstract of DOI:10.1016/S0022-328X(00)00249-7

A new class of mono- (2-4) and bis(undecamethylcyclohexasilanyl) (5-9) substituted germanium, tin and lead compounds is described. These molecules are accessible by treatment of undecamethylcyclohexasilanyl potassium (1) with chlorogermanes, -stannanes or plumbanes. Attempts to generate bis(cyclohexasilanyl)methanes, -plumbanes or tris(cyclohexasilanyl)methylstannane starting from dihalomethanes, -plumbanes or methyltrichlorostannane and 1 result only in transmetallation reactions. The molecular structures of a mono- (3) and a dicyclohexasilanyl stannane derivative 5 were determined by single-crystal X-ray crystallography.

Full text of DOI:10.1016/S0022-328X(00)00249-7

www.elsevier.nl/locate/jorganchem
Journal of Organometallic Chemistry 605 (2000) 22–27
Cyclohexasilanes with exocyclic organogermanium, -tin or -lead
groups
U. Englich a, E. Hengge b, U. Hermann c, C. Marschner b, K. Ruhlandt-Senge a,
F. Uhlig c,*
a Syracuse Uni6ersity, Department of Chemistry, 1-014 Center of Science and Technology, Syracuse, NY, USA
b T.U. Graz, Institute for Inorganic Chemistry, Stremayrgasse 16, A-8010 Graz, Austria
c Dortmund Uni6ersity, Department of Chemistry, Inorganic Chemistry II, Otto-Hahn-Straße 6, D-44221 Dortmund, Germany
Received 24 February 2000; received in revised form 11 April 2000
Abstract
A new class of mono- (2–4) and bis(undecamethylcyclohexasilanyl) (5–9) substituted germanium, tin and lead compounds is
described. These molecules are accessible by treatment of undecamethylcyclohexasilanyl potassium (1) with chlorogermanes,
-stannanes or plumbanes. Attempts to generate bis(cyclohexasilanyl)methanes, -plumbanes or tris(cyclohexasilanyl)-
methylstannane starting from dihalomethanes, -plumbanes or methyltrichlorostannane and 1 result only in transmetallation
reactions. The molecular structures of a mono- (3) and a dicyclohexasilanyl stannane derivative 5 were determined by
single-crystal X-ray crystallography. © 2000 Elsevier Science S.A. All rights reserved.
Keywords: Undecamethylcyclohexasilanyl potassium; Undecamethylcyclohexasilanylstannanes; 1H-, 29Si-NMR; Mass spectroscopy; X-ray crystal-
lography
silicon [11]. Recently, we described the synthesis and
reactivity of a variety of type A and B silicon com-
pounds (Z=Si) [14]. However, so far type A or B
derivatives, where the exocyclic Z is a different Group
14 element, are not known, with the exception of the
permethylated Si6 ring in itself, and other type A car-
bon substituted derivatives (Z=alkyl or aryl). Recently
we communicated in a poster contribution the unde-
camethylcyclohexasilanyl group as a sterically demand-
ing substituent for tin atoms [15]. In an extension to
this work we now describe the syntheses and molecular
structures of germanium, tin and lead derivatives with
one (type A) or two (type B) undecamethylcyclohexasi-
lanyl groups (Z=Ge, Sn, Pb; Fig. 1).
1. Introduction
Undecamethylcyclohexasilanyl derivatives have at-
tracted increasing interest since the first synthesis of
dodecamethylcyclohexasilane in 1949 [1], due to their
interesting electronic and photophysical properties [2–
6]. Two types of compounds, with one (A) or two (B)
cyclohexasilanyl groups have been described (Fig. 1).
In both cases, Z is either a transition metal fragment
[7–9] or a main group element such as a halogen
[10–12], oxygen [12,13], sulfur [12], phosphorus [12] or
2. Results and discussion
Fig. 1. Z=transition metal, O, S, PPh, SiRR% and H, halogene (for
type A).
A convenient starting material for compounds of
type A and B (as depicted in Fig. 1) is the highly
reactive undecamethylcyclohexasilanyl potassium (1).
This precursor can easily be prepared from dode-
camethylcyclohexasilane and potassium tert-butylate
* Corresponding author. Tel.: +49-231-7553812; fax: +49-231-
7555048.
E-mail address: fuhl@platon.chemie.uni-dortmund.de (F. Uhlig).
0022-328X/00/$ - see front matter © 2000 Elsevier Science S.A. All rights reserved.
PII: S0022-328X(00)00249-7

U. Englich et al. / Journal of Organometallic Chemistry 605 (2000) 22–27
23
(Eq. (1)). The reaction mechanism is likely to be based
on complex ring-opening–ring-closing reactions, result-
ing in a theoretical yield of 80% relative to the starting
material cyclohexasilane [16].
The yields of compounds 2–9 are between 30 and
70%. The tin derivatives are more air-sensitive than the
corresponding silanes [11] or the germane 9. For exam-
ple, 3 reacts with dry air within 4 weeks to form
hexaphenyldistannane and a siloxane [12] (11, Eq. (4)).
(1)
(4)
Undecamethylcyclohexasilanyl derivatives of tin(IV) are
formed by reaction of 1 with organotin mono- or
dichlorides at low temperatures (Eqs. (2) and (3)). A
type B germanium compound was prepared by reacting
dimethyldichlorogermane with two equivalents of 1 (9,
Eq. (3)), a type A lead derivative (4) was synthesized by
using triphenylchloroplumbane as starting material.
The lead derivative 4 is even more reactive towards
oxygen and decomposes within minutes when exposed
to air. The reaction of 5 with two equivalents of
mercury dichloride yields dimethyldichlorostannane,
chloroundecamethylcyclohexasilane (12) and elemental
mercury (Eq. (5)).
(2)
(5)
Compounds 2–7 and 9 were characterized by NMR
spectroscopy, mass spectrometry and elemental analy-
sis. Additionally, an EDXRFS [17] (energy dispersive
X-ray fluorescence spectroscopy) experiment was used
to verify the germanium content of compound 9. The
connectivities of the silicon atoms of 3 and 5 were
determined by 29Siꢀ29Si coupling constants and inde-
pendently from the 119/117Snꢀ29Si coupling constants
(Table 1). Compounds 2 and 5 were also characterized
by X-ray crystallography.
Compound 3, depicted in Fig. 2, crystallizes with two
independent molecules per asymmetric unit. Both
molecules display fairly similar geometrical features
with the central Sn atom bound to three phenyl groups,
in addition to one Si6Me11 unit. The Sn atom displays
a slightly distorted tetrahedral environment with angles
ranging between 105.5(1) and 117.9(1)° for Sn(1) and
104.1(2) and 114.1(1)° for Sn(2). The SiꢀSn bond
lengths are observed at 259.3(1) pm for Sn(1) and
259.0(1) pm for Sn(2), while SnꢀC bonds are observed
between 214.9(4) and 216.1(4) pm. The Si6Me11 rings
adopt a chair conformation with SiꢀSi distances be-
tween 234.0(2) and 235.4(2) pm.
(3)
The
reactions
of
dimethyldichloroplumbanes
(Me2PbCl2) and dihalomethanes (CH2X2, X=Cl, Br, I)
did not result in the formation of type B compounds,
since transmetallation reactions result in bis(unde-
camethylcyclohexasilanyl) (10) as the only identifiable
compound. Similar results were observed in the reac-
tion of methyltrichlorostannane with three equivalents
of 1. The reaction does not afford a tin derivative of
type C (Scheme 1), instead transmetallation was ob-
served accompanied by the formation of polystannanes
and 10.
Compound 5, depicted in Fig. 3, displays monomeric
units with no imposed crystallographic symmetry. The
central Sn atom is connected to two methyl groups in
addition to two Si6Me11 units with SnꢀSi linkages of
258.9(2) and 259.3(2) pm and SnꢀC bond lengths of
216.5(9) and 217.6(9) pm. Sn(1) displays a slightly
distorted tetrahedral coordination environment with
angles ranging from 102.7(5)° between the two methyl
Scheme 1. Transmetallation and formation of 10.

24
U. Englich et al. / Journal of Organometallic Chemistry 605 (2000) 22–27
Table 1
29Si- and 119Sn-NMR shifts of undecamethylcyclohexasilanyl-substituted compounds 2–9
Compound
no.
E
R
R%
R%%
119Sn (ppm) 29Si (ppm)/coupling constants in Hz
SiA
SiB
SiC
SiD
2
3
Sn Me
Sn Ph
Me
Ph
Me
Ph
Ph
−168.5
−149.5
−70.8
−36.8
−40.4
−42.2
1J(29Siꢀ119/117Sn):
370/353
2J(29Siꢀ119/117Sn):
65/62
−69.1
−36.7
−39.9
−41.3
1J(29Siꢀ119/117Sn):
314/300
2J(29Siꢀ119/117Sn): 3J(29Siꢀ119/117Sn): 1J(29Siꢀ119/117Sn):
69/66
−37.1
9
6
4
5
Pb Ph
Sn Me
Ph
−72.0
−40.2
−41.9
1J(29Siꢀ207Pb): 648
−70.4
Me
Si6Me11 −206.3
Si6Me11 −191.2
Si6Me11 −192.3
−40.2
−35.8
−42.0
−42.3
−42.7
−42.2
−34.0
1J(29Siꢀ119/117Sn):
204/194
2J(29Siꢀ119/117Sn): 3J(29Siꢀ119/117Sn):
51
−35.5
10
6 a
7
Sn Me
Sn Ph
Ph
Ph
−69.1
−40.3/−40.9
1J(29Siꢀ119/117Sn):
204/195
−62.9
−35.5
−40.1
−40.3
−39.6
1J(29Siꢀ119/117Sn):
170/163
2J(29Siꢀ119/117Sn):
62/59
8
Sn p-MePh p-MePh Si6Me11 −192.3
−64.1
−36.1
1J(29Siꢀ119/117Sn):
173/167
2J(29Siꢀ119/117Sn):
63/60
9
Ge Me
Me
Si6Me11
−76.9
−41.9
a Only NMR-spectroscopically determined.
groups, up to 113.65(6)° between the two sterically
more demanding Si6Me11 moieties. The Si6 ring is in a
chair conformation, with SiꢀSi distances in the range of
233.6(3)–235.7(3) pm.
Functionalization reactions at the tin atoms of 3 and
5 with triflic acid–lithium chloride or tetrachlorostan-
nane are rather complex and will be described in detail
in an upcoming publication.
3. Experimental
Fig. 2. Molecular structure of compound 3 showing 50% probability
displacement ellipsoids (ORTEP3).
All procedures were carried out under an atmosphere
of inert gas using standard Schlenk techniques. Solvents
were dried by standard procedures and used after being
freshly distilled [18]. All organo-substituted mono-, di-
and trichlorostannanes [19] and undecamethylcyclohex-
asilanyl potassium [16] were prepared according to
published procedures.
scope with an AN-1270 EDX system by Link was used
for the EDXRFS [17] experiment.
NMR spectra were recorded on Bruker DRX 300
(29Si: 59.63 MHz, 119Sn: 111.92 MHz) and DPX 400
(1H: 400.15 MHz, 13C: 100.63 MHz, 29Si: 79.49 MHz,
1
119Sn: 149.21 MHz) spectrometers. The JSiꢀSi-coupling
constants were determined using an INEPT-INADE-
QUATE technique [20–22]. Mass spectra were ob-
tained using a MAT 8200 mass spectrometer. A
Cambridge Stereoscan 360 Scanning Electron Micro-
Fig. 3. Molecular structure of compound 5 showing 30% probability
displacement ellipsoids (ORTEP3).

U. Englich et al. / Journal of Organometallic Chemistry 605 (2000) 22–27
25
3.1. General procedure for the preparation of mono-
and bis-undecamethylcyclohexasilanyl-substituted
stannanes, germanes and plumbanes 2–9
mmol KSi6Me11; m.p. (dec.): 75–83°C, yellow–white
solid. Yield: 1.3 g (30%). 1H-NMR: 0.15 (m) [3×
SiMe2], 0.24 (s) [2×SiMe2], 55 (s) [1×SiMe], 7.18–
7.65 (m) [3×Ph]. Elemental analysis: C29H48PbSi6,
MW=772.4 g mol−1. No satisfactory elemental analy-
sis could be obtained.
A solution of 11.2 (n=2) or 5.6 mmol (n=3) of
element chloride RnEX4−n (n=2, 3) in 20 ml of te-
trahydrofurane (thf) is cooled to −50°C and stirred. A
solution of 11.2 mmol undecamethylcyclohexasilanyl
potassium (1)1 in 20 ml diethyleneglycoldimethylether
(diglyme) is added dropwise over a period of 1 h. The
solution is then stirred for another 12 h. The solvent is
removed in vacuo, followed by addition of 50 ml of
hexane. The insoluble residue is removed by filtration,
and the hexane is removed by evaporation under re-
duced pressure.
3.1.4. Bis(undecamethylcyclohexasilanyl)-
dimethylstannane (5)
Starting materials: 1.23 g (5.6 mmol) Me2SnCl2, 11.2
mmol KSi6Me11; colorless solid, m.p.: 145–153°C.
Yield: 3.75 g (82%). 1H-NMR: 0.11–0.30 (m) [22×
SiMe], 1.15 (m) [2×Me]. 13C-NMR: −7.8 [2×SnMe];
−6.7, −5.0, −4.1, −1.8 [22×SiMe]. 29Siꢀ29Si cou-
1
1
pling constants: J(SiAꢀSiB): 49 Hz, J(SiBꢀSiC): 60 Hz,
2
2
After addition of 50 ml of ethanol the resulting
solution is stored at −20°C for 24 h. During storage a
solid is formed, which is isolated by filtration and
recrystallized from 100 ml of acetone.
1J(SiCꢀSiD): 61.5 Hz, J(SiAꢀSiC): 7.5 Hz, J(SiBꢀSiD):
9.5 Hz. MS: 73 [5%, SiMe3], 334 [20%, Si6Me11], 468
[30%, Si6Me11−SnMe], 800 [10%, M+−Me], 815 [8%,
M+]; Elemental analysis: C24H72Si12Sn, MW=816.56 g
mol−1. Found (Calc.): C, 36.8 (35.4); H, 9.2 (8.8).
3.1.1. (Undecamethylcyclohexasilanyl)trimethylstannane
(2)
3.1.5. Bis(undecamethylcyclohexasilanyl)-
methylphenylstannane (6)
Starting materials: 1.58 g (5.6 mmol) MePhSnCl2,
Starting materials: 2.23 g (11.2 mmol) Me3SnCl, 11.2
mmol KSi6Me11; colorless solid, m.p.: 68°C; Recrystal
lization from 1:5 n-pentane–n-propanol. Yield: 2.50 g
(45%). 1H-NMR: 0.25 [SnMe3, 2J(1Hꢀ119/117Sn: 42)],
0.23, 0.17 [11×SiMe]. 13C-NMR: −1.1 [SnMe3
1J(13Cꢀ119/117Sn): 258/246 Hz], −3.1, −4.6, −5.0,
−5.3, −6.4, −10.0 [1×SiMe]. 29Siꢀ29Si coupling con-
stants: 1J(SiAꢀSiB): 52 Hz, 1J(SiBꢀSiC): 59.5 Hz,
11.2 mmol KSi6Me11; colorless oil. Yield: 3.40 g (69%).
3.1.6. Bis(undecamethylcyclohexasilanyl)-
diphenylstannane (7)
Starting materials: 1.93 g (5.6 mmol) Ph2SnCl2, 11.2
mmol KSi6Me11; colorless solid, m.p.: 170–172°C.
Yield: 3.70 g (70%). 1H-NMR: 7.25–7.6 (m) [2×SnPh],
0.54 [2×SiMe], 0.33 [4×SiMe2], 0.14 [6×SiMe2]; Ele-
mental analysis: C34H76Si12Sn, MW=940.72. Found
(Calc.): C, 43.9 (43.4); H, 8.1 (7.5).
2
2
1J(SiCꢀSiD): 60 Hz, J(SiAꢀSiC): 6 Hz, J(SiBꢀSiD): 7.5
Hz. MS: 333 [100%, Si6Me11], 451 [20%, Si6Me11Sn],
481 [5%, M+−Me], 497 [5%, M+]; Elemental analysis:
C14H42Si6Sn, MW=497.7 g mol−1. Found (Calc.): C,
32.5 (33.8); H, 8.7 (8.5).
3.1.7. Bis(undecamethylcyclohexasilanyl)bis-
(p-methylphenyl)stannane (8)
Starting materials: 2.10 g (5.6 mmol) (p-MePh)2-
3.1.2. (Undecamethylcyclohexasilanyl)triphenylstannane
(3)
Starting materials: 4.31 g (11.2 mmol) Ph3SnCl, 11.2
mmol KSi6Me11; colorless solid, m.p.: 118°C. Yield:
5.90 g (77%). 1H-NMR: 0.11–0.55 (m) [11×SiMe],
7.22–7.53 (m) [3×Ph]. 13C-NMR: 140.2 [2×Ci,
1J(13Cꢀ119/117Sn): 398/380 Hz]; 137.9 [4×Co, 2J(13Cꢀ119/117
Sn): 40 Hz]; 127.8 [4×Cm, 3J(13Cꢀ119/117Sn): 44 Hz];
127.8 [2×Cp]; −7.5, −4.9, −4.1, −1.8 [22×SiMe].
MS: 73 [6%, SiMe3], 273 [15%, SnPh2], 334 [20%,
Si6Me11], 350 [17%, SnPh3], 684 [10%, M+]. Elemental
analysis: C29H48Si6Sn, MW=683.91 g mol−1. Found
(Calc.): C, 48.8 (51.0); H, 7.2 (7.0).
SnCl2, 11.2 mmol KSi6Me11; colorless solid, m.p.: 146–
149°C. Yield: 4.30 g (78%). H-NMR: 7.35 (d), 7.66 (d)
[2×C4H4], 2.35 (s) [2×CMe], 0.49 [2×SiMe], 0.36
[4×SiMe2], 0.18 [6×SiMe2]. Elemental analysis:
C36H80Si12Sn, MW=968.76 g mol−1. Found (Calc.):
C, 43.9 (44.6); H, 8.1 (8.3).
1
3.1.8. Bis(undecamethylcyclohexasilanyl)-
dimethylgermane (9)
Starting materials: 0.97 g (5.6 mmol) Me2GeCl2, 11.2
mmol KSi6Me11; colorless solid, m.p.: 148–150°C.
Yield: 3.65 g (85%). 1H-NMR: 0.13–0.24 (m) [22×
SiMe], 1.23 [2×GeMe]. 13C-NMR: −8.7 [2×GeMe2],
−6.9, −4.7, −4.3, −2.6 [22×SiMe/SiMe2]. MS: 334
[20%, Si6Me11], 753 [30%, M+−Me], 768 [3%, M+].
3.1.3. (Undecamethylcyclohexasilanyl)triphenylplumbane
(4)
Starting materials: 2.65 g (5.6 mmol) Ph3PbCl, 5.6
Elemental analysis: C24H72Si12Sn, MW=770.46
g
mol−1. Found (Calc.): C, 38.1 (37.4); H, 9.2 (9.4); Ge
11.4 (7.7); Si, 88.6 (92.3) (by EDXRFS [17]).
1 Prepared from 4.88g (14 mmol) dodecamethylcyclohexasilane and
1.57 g (14 mmol) potassium tert-butylate.

26
U. Englich et al. / Journal of Organometallic Chemistry 605 (2000) 22–27
1
spectroscopy. 119Sn-NMR: −144 ppm, J(119Snꢀ117Sn):
4420 Hz [23]. 29Si-NMR: 6.3, −43.7, −42.5, −42.2
ppm [12].
Table 2
Selected bond lengths (pm) and bond angles (°) of the structures of 3
and 5
3
5
3.3. Reaction of 5 with mercury dichloride
Bond lengths
Si(1)ꢀSn(1)
Si(7)ꢀSn(1)
Si(1)ꢀSi(2)
Si(2)ꢀSi(3)
Si(3)ꢀSi(4)
Si(4)ꢀSi(5)
Si(5)ꢀSi(6)
Si(6)ꢀSi(1)
259.31(11)
259.3(2)
258.9(2)
234.9(3)
234.2(3)
234.7(3)
233.6(3)
235.2(3)
234.9(3)
A total of 2.5 g (9.2 mmol) mercury dichloride and
20 ml of thf were placed in a Schlenk tube. A solution
of 3.75 g (4.6 mmol) 5 in 50 ml of thf was added slowly
at room temperature over a period of 2 h. After an
additional 4 h of stirring the reaction was complete and
the solvent was then removed in vacuo. Sublimation in
vacuo yielded 2.90 g of 11 (83%). The physical and
spectroscopic data of 11 are given in [10].
234.6(2)
234.0(2)
234.6(2)
234.5(2)
234.9(2)
234.7(2)
Bond angles
C(18)ꢀSn(1)ꢀC(24)
C(18)ꢀSn(1)ꢀSi(1)
C(24)ꢀSn(1)ꢀSi(1)
C(12)ꢀSn(1)ꢀSi(1)
C(12)ꢀSn(1)ꢀC(18)
C(12)ꢀSn(1)ꢀC(24)
C(18)ꢀSn(1)ꢀSi(7)
C(24)ꢀSn(1)ꢀSi(7)
Si(1)ꢀSn(1)ꢀSi(7)
105.50(14)
117.86(10)
107.39(10)
112.26(10)
106.19(14)
106.98(14)
102.7(5)
109.1(3)
110.7(3)
3.4. Crystallography of 3 and 5
The crystals were mounted on the diffractometer as
previously described [24]. Intensity data were collected
with graphite monochromated MoꢀKa radiation (u=
109.6(3)
110.5(3)
113.65(6)
,
0.71073 A), using a Siemens SMART system, complete
with three-circle goniometer and CCD detector operat-
ing at −54°C. An absorption correction was applied
utilizing the program SADABS [25]. The crystal structure
was solved by direct methods, as included in the
SHELXTL-PLUS program package [26]. Missing atoms
were located in subsequent difference Fourier maps and
included in the refinement. Remaining hydrogen atoms
were placed geometrically and refined using a riding
model with Uiso constrained at 1.2 for non-methyl
groups, and 1.5 for methyl groups times Ueq of the
carrier carbon atom. The structure was refined by full-
matrix least-squares refinement on F2 (SHELXL-93) [27]
(Tables 2 and 3). Scattering factors were those provided
with the SHELXL program system. All non-hydrogen
atoms, with the exception of some disordered or re-
strained positions were refined anisotropically. Disorder
was handled by including split positions for the affected
groups, and included in the refinement of the respective
occupancies. A set of restraints was applied to aid in
modeling the disorder.
Table 3
Summary of data collection, structure solution and refinement of 3
and 5
3
5
Empirical formula
Formula weight
Space group
Crystal color, habit
C29H48Si6Sn
683.905
Triclinic, P1
Colorless, plate
0.40×0.15×0.05 0.40×0.32×0.04
869.24(2)
1801.95(5)
2499.16(6)
76.648(1)
80.601(1)
88.405(1)
3757.4(2)
4
C24H72Si12Sn
816.59
Triclinic, P1
(
(
Colorless, plate
Crystal size (mm)
a (pm)
b (pm)
c (pm)
h (°)
i (°)
k (°)
V
984.03(4)
1494.30(6)
1769.12(7)
100.881(1)
98.369(1)
100.544(1)
2467.4(2)
2
Z
Dcalc (g cm−3
)
1.209
1.099
0.823
Linear absorption coefficient 0.887
(mm−1
)
Radiation
T (K)
MoꢀKa
150(2)
MoꢀKa
150(2)
1.19–25.00
8270 [0.0370]
q Range for data collection 1.16–28.27
Independent reflections 16 414 [0.0270]
(Rint
)
Number of parameters
Goodness-of-fit on F2
R1, wR2 [I\2|(I)]
R1, wR2 (all data)
650
1.125
0.0527, 0.0877
0.0771, 0.0973
334
1.114
0.0711, 0.1549
0.1067, 0.1970
4. Supplementary material
Crystallographic data for the structural analysis have
been deposited with the Cambridge Crystallographic
Data Centre, CCDC no. 101462 for compounds 3 and
5. Copies of this information may be obtained free of
charge from: The Director, CCDC, 12 Union Road,
Cambridge, CB2 1EZ, UK (Fax: +44-1223-336033;
e-mail: deposit@ccdc.cam.ac.uk or www: http://
www.ccdc.cam.ac.uk).
3.2. Reaction of 3 with dry oxygen
A total of 2.4 g (3.5 mmol) of 3 were placed in a
one-necked flask fitted with a drying tube (CaCl2).
After 4 weeks the residue was analyzed by NMR

U. Englich et al. / Journal of Organometallic Chemistry 605 (2000) 22–27
27
[10] M. Ishikawa, M. Kumada, Synth. Inorg. Met. Org. Chem. 1
(1971) 191.
Acknowledgements
[11] F.K. Mitter, G.I. Pollhammer, E. Hengge, J. Organomet. Chem.
314 (1986) 1.
[12] E. Hengge, M. Eibl, J. Organomet. Chem. 371 (1989) 137.
[13] C. Lagoet, J.C. Maire, M. Ishikawa, M. Kumada, J. Organomet.
Chem. 57 (1973) C39.
[14] U. Englich, S. Graschy, E. Hengge, U. Hermann, C. Marschner,
C. Mechtler, E. Pinter, K. Ruhlandt-Senge, F. Uhlig, J.
Organomet. Chem. 598 (2000) 202.
[15] F. Uhlig, U. Hermann, K. Klinkhammer, E. Hengge, Auner,
Weis (Eds.), Organosilicon Chemistry III, From Substances to
Materials, VCH, Weinheim, 1997, pp. 322.
This work was supported by the Deutsche
Forschungsgemeinschaft (DFG), the Fond der Chemis-
chen Industrie (Germany), the National Science Foun-
dation (NSF) and the Fonds zur Fo¨rderung der
8
wissenschaftlichen Forschung in Osterreich (FWF), the
W.M. Keck Foundation and Syracuse University. F.U.
is grateful to Professor Dr K. Jurkschat (Dortmund
University) for his interest in this work. Ch.M. is the
recipient of an APART (Austrian Program for Ad-
vanced Research and Technology) scholarship from the
Austrian Academy of Science.
[16] F. Uhlig, P. Gspaltl, M. Trabi, E. Hengge, J. Organomet. Chem.
493 (1995) 33.
[17] L. Reimer, G. Pfefferkorn, Raster-Elektronenmikroskopie,
Springer, Berlin, 1973.
[18] W. Bunge, Houben, Weyl, Methoden der organischen Chemie,
vols. 1/2, G. Thieme, Stuttgart, Germany, 1959.
[19] R.K. Ingham, S.D. Rosenberg, H. Gilman, Chem. Rev. 60
(1960) 459.
References
[1] C.A. Burkhard, J. Am. Chem. Soc. 71 (1949) 963.
[2] I. Masahiro, I. Setsuko, O. Kunio, N. Ren, J. Organomet.
Chem. 388 (1990) 253.
[20] E. Hengge, F. Schrank, J. Organomet. Chem. 362 (1989) 11.
[21] O.W. Sorensen, R. Freeman, T.A. Frenkiel, T.H. Mareci, R.
Schuck, J. Magn. Reson. 46 (1982) 180.
[3] R. West, V.F. Treven, J. Am. Chem. Soc. 95 (1973) 6824.
[4] E. Carberry, R. West, G.E. Glass, J. Am. Chem. Soc. 91 (1969)
5446.
[5] E. Hengge, P.K. Jenkner, R. Czaputa, C. Kratky, J. Organomet.
Chem. 446 (1993) 83.
[6] K. Hassler, Spectrochim. Acta Part A 37 (1981) 541.
[7] W. Palitzsch, U. Bo¨hme, C. Beyer, G. Roewer, Organometallics
17 (1998) 2965.
[8] E. Hengge, E. Pinter, M. Eibl, F. Uhlig, Bull. Soc. Chim. Fr. 132
(1995) 509.
[22] E. Hengge, M. Eibl, Organometallics 10 (1991) 3185.
[23] B. Wrackmeyer, Annu. Rep. NMR Spectrosc. 16 (1985) 73.
[24] S. Chadwick, U. Englich, K. Ruhlandt-Senge, Chem. Commun.
(1998) 2149.
[25] G.M. Sheldrick, SADABS: Program for Absorption Correction
Using Area Detector Data, University of Go¨ttingen, Germany,
1996.
[26] Siemens SHELXTL-PLUS, Program Packet for Structure Solution
and Refinement, Siemens, Madison, WI, 1996.
[27] G.M. Sheldrick, SHELXL-93, Program for Crystal Structure
Refinement, University of Go¨ttingen, Germany, 1993.
[9] P. Gspaltl, Ph.D. Thesis, T.U. Graz, 1995
.