Group 14 chalcogenides featuring a bicyclo[3.3.0]octane skeleton

Article abstract of DOI:10.1016/S0022-328X(01)01010-5

Reactions of mixtures of Cl₂MeSiSiMeCl₂ (1) and Me₂MCl₂ (M=Si, Ge, Sn) with either H₂S/NEt₃ or Li₂E (E=Se, Te) yielded the bicyclo[3.3.0]octanes Me₂M(E)₂Si₂Me₂(E)₂MMe₂. A carbon containing analog, (CH₂)₅C(S)₂Si₂Me₂(S)₂C(CH₂)₅, was prepared from 1 and (CH₂)₅C(SH)₂. Crystal structures of three of these compounds were determined and the observed conformations of the bicyclo[3.3.0]octane skeletons compared with results of density functional theory calculations. Another class of silchalcogenides featuring a bicyclo[3.3.0]octane skeleton, E(Me₂Si)₂Si₂Me₂(SiMe₂)₂E, was formed from the doubly branched hexasilane (ClMe₂Si)₂Si₂Me₂(SiMe₂Cl)₂ and H₂S/NEt₃ or Li₂E. All products were characterized by multinuclear NMR (¹H, ¹³C, ²⁹Si, ⁷⁷Se, ¹¹⁹Sn, and ¹²⁵Te).

Full text of DOI:10.1016/S0022-328X(01)01010-5

Journal of Organometallic Chemistry 630 (2001) 139–148
www.elsevier.com/locate/jorganchem
Group 14 chalcogenides featuring a bicyclo[3.3.0]octane skeleton
U. Herzog a,*, U. Bo¨hme a, E. Brendler b, G. Rheinwald c
a Institut fu¨r Anorganische Chemie der TU Bergakademie Freiberg, Leipziger Str. 29, D-09596 Freiberg, Germany
b Institut fu¨r Analytische Chemie der TU Bergakademie Freiberg, Leipziger Str. 29, D-09596 Freiberg, Germany
c Institut fu¨r Chemie, Lehrstuhl Anorganische Chemie, TU Chemnitz, Straße der Nationen 62, D-09111 Chemnitz, Germany
Received 8 November 2000; accepted 21 May 2001
Abstract
Reactions of mixtures of Cl2MeSiSiMeCl2 (1) and Me2MCl2 (M=Si, Ge, Sn) with either H2S/NEt3 or Li2E (E=Se, Te) yielded
the bicyclo[3.3.0]octanes Me2M(E)2Si2Me2(E)2MMe2. A carbon containing analog, (CH2)5C(S)2Si2Me2(S)2C(CH2)5, was prepared
from 1 and (CH2)5C(SH)2. Crystal structures of three of these compounds were determined and the observed conformations of
the bicyclo[3.3.0]octane skeletons compared with results of density functional theory calculations. Another class of silchalco-
genides featuring a bicyclo[3.3.0]octane skeleton, E(Me2Si)2Si2Me2(SiMe2)2E, was formed from the doubly branched hexasilane
(ClMe2Si)2Si2Me2(SiMe2Cl)2 and H2S/NEt3 or Li2E. All products were characterized by multinuclear NMR (1H, 13C, 29Si, 77Se,
119Sn, and 125Te). © 2001 Elsevier Science B.V. All rights reserved.
Keywords: Group 14 chalcogenides; bicyclo[3.3.0]octane skeleton; density functional theory calculations
1. Introduction
five-membered heterocyclic compound is formed
preferably:
The reaction of organochlorosilanes with either H2E
(E=S, Se) in the presence of a Lewis base or Li2E
(E=S, Se, Te) yields silicon chalcogenides which usu-
ally form four- or six-membered heterocycles or polycy-
cles with adamantane [1] or double-decker [2,3]
structures depending on the functionality of the starting
chlorosilane and the steric demand of the organic
substituents.
Density functional theory (DFT) calculations on the
conversion reaction:
In our previous report on cyclic and polycyclic silthi-
anes containing Si–Si bonds [4] we have shown that in
this class of compounds five-membered heterocycles
consisting of three silicon and two sulfur atoms are
most stable. The reaction of Me2SiCl2 with H2S/NEt3
yields the six-membered ring compound (Me2SiS)3 and
the analogous reaction of the disilane ClMe2Si–
SiMe2Cl results in the formation of the six-membered
heterocycle S(SiMe2SiMe2)2S without any acyclic by-
products. If, however the reaction with H2S/NEt3 is
carried out with a mixture of the two chlorosilanes, a
have indeed shown that the five-membered cyclic com-
pound is 36 kJ mol−1 more stable than the correspond-
ing mixture of the two six-membered heterocycles. This
tendency also applies to systems with heavier Group 14
elements like germanium and tin and the heavier
chalcogens selenium and tellurium. For instance the
reaction of equimolar mixtures of Me2MCl2 (M=Ge,
Sn) and ClMe2Si–SiMe2Cl with Li2Se or Li2Te resulted
in a selective formation of the five-membered heterocy-
cles Me2M(E)2Si2Me4 [5]:
* Corresponding author. Tel.: +49-3731-394-343; fax: +49-3731-
394-058.
E-mail address: herzog@merkur.brz.tu-freiberg.de (U. Herzog).
0022-328X/01/$ - see front matter © 2001 Elsevier Science B.V. All rights reserved.
PII: S0022-328X(01)01010-5

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The aim of this work is to extend these investigations
to bicyclo[3.3.0]octanes also containing other Group 14
elements (C, Ge, Sn) and/or heavier chalcogens (Se,
Te).
In continuation of these studies a mixture of the
tetrafunctional disilane Cl2MeSi–SiMeCl2 (1) and
Me2SiCl2 in a molar ratio of 1:2 is now shown to react
with H2S/NEt2 yielding selectively 1,3,3,5,7,7-hexam-
ethyl-2,4,6,8-tetrathiatetrasila-bicyclo[3.3.0]octane (2a):
The molecular structure of 2a as determined by X-
ray analysis revealed two fused five-membered rings
adopting envelope conformations with one SiMe2 unit
in an exo and one in an endo position [4], see Fig. 1.
2. Results and discussion
2.1. Formation of
2,4,6,8-tetrachalcogena-bicyclo[3.3.0]octanes
Reacting 1:2 mixtures of 1 and the dichloro com-
pounds Me2MCl2 (M=Ge, Sn) or Ph2SnCl2 with H2S/
NEt3 the corresponding bicyclo[3.3.0]octanes 2b–d are
formed in high yields:
The carbon containing derivative 2e could be pre-
pared by treatment of 1 with two equivalents of cyclo-
hexane-1,1-dithiol which had been prepared from
cyclohexanone and H2S according to Ref. [6]:
Fig. 1. ORTEP plot of the molecular structure of 2a [4].
Table 1
NMR data (chemical shifts in ppm, coupling constants in Hz) of the
bicyclo[3.3.0]octanes R2M(S)2Si2Me2(S)2MR2 (2a–e) (MR2=SiMe2,
GeMe2, SnMe2, SnPh2, C(CH2)5)
Analogous selenium and tellurium containing bicy-
clo[3.3.0]octanes (3a–c, 4a–c) have been synthesized by
analogous reactions of mixtures of 1 and Me2MCl2
(M=Si, Ge, Sn) with either Li2Se or Li2Te in THF
solution:
All newly prepared 2,4,6,8-tetrachalcogena-bicy-
clo[3.3.0]octanes are colorless solids. Their stability to-
wards moisture and air decreases dramatically from the
sulfur via the selenium to the tellurium heterocycles.
Nevertheless all compounds could be characterized by
multinuclear NMR spectroscopy, see Tables 1 and 2,
and in some cases by GC–MS.

U. Herzog et al. / Journal of Organometallic Chemistry 630 (2001) 139–148
141
Table 2
NMR data (chemical shifts in ppm, coupling constants in Hz) of the bicyclo[3.3.0]octanes Me2M(E)2Si2Me2(E)2MMe2 (3a–4c) (M=Si, Ge, Sn;
E=Se, Te)
While the chemical shifts of M (C, Si, Sn) in the MR2
units of 2a–4c are similar to those of the corresponding
five-membered monocyclic compounds Me4Si2(E)2MR2
[5] (in most cases slightly shifted to lower field), the
selenium and tellurium resonances are observed by
60–105 ppm further downfield. Due to the bicyclic
systems in 2a–4c the two organic substituents at M are
diastereotopic giving rise to two different 1H- and
13C-NMR signals.
conformation could be the larger bond lengths of Sn–
Se as well as Se–Si whereas the central Si–Si bond
remains the same.
Comparing the geometries of 2e, 2a and 2b it can be
seen that in this series of compounds with the ring
atoms M (C, Si, Ge) the Si–Si bond length increases
from 2.328(1) (2e) via 2.360(1) (2a) to 2.367(1) (2b).
Consistently the average bond angles Si–S–M
(101.99 ° in 2e, 99.12 ° in 2a, 98.72 ° in 2b) and
S–M–S (112.31 ° in 2e, 107.91 ° in 2a, 105.28 ° in 2b)
2.2. Molecular structures of
2,4,6,8-tetrachalcogena-bicyclo[3.3.0]octanes
X-ray structure analyses have been carried out for 2b,
2e and 3c while the molecular structure of 2a has been
reported previously [4]. Figs. 2–4 show the molecular
structures. Compounds 2a and 2b crystallize in the
same space group with almost identical unit cell
parameters (Tables 3–5).
While the bicyclo[3.3.0]octane skeletons of 2a, 2b and
2e adopt a bis-envelope conformation, it is obvious that
a rather twisted conformation of both five-membered
rings is observed for 3c. The reasons for this different
Fig. 2. Molecular structure of 2b.

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U. Herzog et al. / Journal of Organometallic Chemistry 630 (2001) 139–148
experimentally observed bis-envelope conformation and
one with a twisted conformation similar to that ob-
served for 3c. For the tin compounds (2c and 3c) only
one minimum corresponding to the twist conformation
could be found. Whereas for 2f the bis-envelope confor-
mation is definitely more stable by 7.4 kJ mol−1 the
differences for 2a are very small (0.4 kJ mol−1, see also
Table 6 and Fig. 5) and for 2b the twist conformation
is 3.65 kJ mol−1 lower in energy.
These calculations suggest, that in solution both con-
formations of 2a are present. Indeed, a 29Si-CP-MAS-
NMR spectrum of the crystalline compound 2a shows
significant differences of the chemical shift values (27.0
ppm for the central Si2Me2 unit and 36.4/31.7 ppm for
the two SiMe2 units) from those obtained from solution
(Table 1), even if one compares the average value of the
two crystallographic different SiMe2 units, see Fig. 6.
On the other hand, a 29Si-CP-MAS-NMR spectrum
of S(SiMe2-SiMe2)2S revealed two signals at −4.83 and
−4.56 ppm. This observation is in accordance with the
crystal structure analysis [5] showing two crystallo-
graphically different silicon atoms while in solution a
very similar 29Si-NMR chemical shift of −4.76 ppm
was observed [5]. Here, the six-membered heterocycle
adopts a chair conformation in solution as well as in
the solid state.
Fig. 3. Molecular structure of 2e.
Fig. 4. Molecular structure of 3c.
Table 4
Selected bond distances and angles of 2e
Table 3
Selected bond distances and angles of 2b
,
Atoms
Distances (A)
Atoms
Angles (°)
,
Atoms
Distances (A)
Atoms
Angles (°)
Si(1)–Si(2)
S(1)–Si(2)
S(2)–Si(1)
S(3)–Si(1)
S(4)–Si(2)
S(1)–C(1)
S(2)–C(1)
S(3)–C(7)
S(4)–C(7)
Si(1)–C(13)
Si(2)–C(14)
2.3275(7)
2.1330(7)
2.1378(7)
2.1463(7)
2.1486(7)
1.863(2)
1.865(2)
1.864(2)
1.864(2)
1.863(2)
1.863(2)
S(1)–Si(2)–S(4) 112.89(3)
S(2)–Si(1)–S(3) 113.57(3)
Si(1)–Si(2)–S(1) 100.58(3)
Si(1)–Si(2)–S(4) 100.32(3)
Si(2)–Si(1)–S(2) 100.17(3)
Si(2)–Si(1)–S(3) 100.26(3)
Si(1)–S(2)–C(1) 103.11(6)
Si(2)–S(1)–C(1) 103.59(6)
Si(1)–S(3)–C(7) 100.46(6)
Si(2)–S(4)–C(7) 100.79(6)
S(1)–C(1)–S(2) 112.37(10)
S(3)–C(7)–S(4) 112.25(10)
Si(1)–Si(1a)
S(1)–Si(1)
S(2)–Si(1)
S(1)–Ge(1)
S(2)–Ge(2)
Si(1)–C(3)
Ge(1)–C(1)
Ge(1)–C(2)
Ge(2)–C(4)
Ge(2)–C(5)
2.3672(9)
2.1422(6)
2.1317(6)
2.2360(5)
2.2457(4)
1.859(2)
1.928(3)
1.931(3)
1.933(2)
1.929(2)
S(1)–Si(1)–S(2)
109.80(2)
106.58(2)
105.89(2)
98.87(2)
S(1)–Si(1)–Si(1a)
S(2)–Si(1)–Si(1a)
Si(1)–S(1)–Ge(1)
Si(1)–S(2)–Ge(2)
S(1)–Ge(1)–S(1a)
S(2)–Ge(2)–S(2a)
C(1)–Ge(1)–C(2)
C(4)–Ge(2)–C(5)
98.58(2)
106.77(2)
103.79(2)
115.91(14)
115.31(11)
decrease while the average angles Si–Si–S increase
from 100.33 (2e) via 105.16 ° (2a) to 106.24 ° (2b). This
is attributed to an increase in the bond lengths S–C,
S–Si, S–Ge. The angles between the planes Si2S2 and
S2M which characterize the envelope conformation of
the related heterocycles vary only slightly between 49
and 50 °.
In order to get a better understanding of these differ-
ences we have performed DFT calculations on the
bicyclo[3.3.0]octanes Me2C(S)2Si2Me2(S)2CMe2 (2f) as a
model for 2e, 2a, 2b, 2c and 3c. For 2f, 2a and 2b two
conformations were found as minima, one with the
Table 5
Selected bond distances and angles of 3c
,
Atoms
Distances (A)
Atoms
Angles (°)
Si(1)–Si(1a)
Si(1)–Se(1)
Si(1)–Se(2a)
Sn(1)–Se(1)
Sn(1)–Se(2)
Si(1)–C(3)
Sn(1)–C(1)
Sn(1)–C(2)
2.333(2)
Se(1)–Si(1)–Se(2a)
Si(1a)–Si(1)–Se(1)
Si(1)–Si(1a)–Se(2)
Si(1)–Se(1)–Sn(1)
Si(1a)–Se(2)–Sn(1)
Se(1)–Sn(1)–Se(2)
C(1)–Sn(1)–C(2)
109.51(4)
105.84(4)
106.88(6)
98.61(3)
96.39(3)
107.79(1)
120.3(2)
2.2802(10)
2.2751(10)
2.5546(5)
2.5566(4)
1.861(4)
2.119(4)
2.126(4)

U. Herzog et al. / Journal of Organometallic Chemistry 630 (2001) 139–148
143
Table 6
Results of the DFT calculations on Me2M(S)2Si2Me2(S)2MMe2 (2f, a–c; M=C, Si, Ge, Sn) and Me2Sn(Se)2Si2Me2(Se)2SnMe2 (3c)
Compound
M
2f
C
2a
Si
2b
Ge
2c
Sn
3c
Sn
Conformation Bis-envelope
Twist
Bis-envelope
Twist
Bis-envelope
Twist
Twist
Twist
Total energy −2487.59397 −2487.59096 −2990.56098 −2990.56125 −2419.04330 −2419.04480 −2418.25497 −862.39606
(H)
Total energy −2487.34091 −2487.33809 −2990.32305 −2990.32320 −2418.80780 −2418.80919 −2418.02269 −862.16696
with zero
point
correction
(H)
,
Si–Si (A)
2.352
2.326
2.381
2.353
2.393
2.360
2.365
2.371
,
Si–S (A)
2.175, 2.158
1.884, 1.884
101.6, 102.8
2.160, 2.174
1.875, 1.900
107.1, 103.7
2.178, 2.165
2.184, 2.178
100.3, 101.0
2.180, 2.166
2.189, 2.179
105.0, 101.2
2.178, 2.163
2.282, 2.289
100.3, 101.8
2.180, 2.165
2.297, 2.284
104.4, 100.1
2.165, 2.185
2.445, 2.455
103.5, 99.1
2.333, 2.353
2.631, 2.639
100.8, 96.7
,
M–S (A)
Si–S–M (°)
If both conformations of 2a were present in solution,
the NMR data of 2a should be temperature dependent
since lower temperature would favor the more stable
1
conformation. Indeed, both the 29Si- and the H-NMR
spectra show changes with temperature (Fig. 7a,b).
Only one of the two SiMe2 proton resonances (A) does
not vary significantly with temperature, probably
due to identical chemical shift values in both
conformations.
For the germanium compound 2b there is a contra-
diction between the results of the DFT calculation and
the observed molecular structure. Here, crystal packing
forces probably stabilize the bis-envelope conformation.
On the other hand, the structure of the tin and selenium
containing compound 3c is again in accordance with
the result of the calculations. However, it must be
noted that there are additional but weak intermolecular
contacts between selenium and tin atoms. The inter-
atomic distances are, with values between 4.0 and 4.1
Fig. 5. Relative stabilities of the bis-envelope and twist conformations
of Me2M(S)2Si2Me2(S)2MMe2, 2f, 2a–c (M=C, Si, Ge, Sn) as
obtained from DFT calculations at the level B3LYP/6-31G*.
,
A, slightly below the sum of the van-der-Waals radii of
,
4.2 A, also see Fig. 8. These intermolecular contacts
lead to the formation of wavy sheets of silicon, sele-
nium and tin atoms perpendicular to the crystallo-
graphic b-axis.
Taking into account these intermolecular contacts
the coordination number of selenium increases to three
with a sum of the three bond angles of 322.6 ° at Se1
and 318.5 ° at Se2 and that of tin reaches six. The
coordination sphere at tin can be regarded as a doubly
capped tetrahedron characterized by Se1–Sn1–Se1b
and Se2–Sn1–Se2b angles of 175.0 and 166.8 °, respec-
tively. Such intramolecular contacts have already been
reported for other tin selenium compounds, for exam-
ple in Me2Sn(Se)2Sn2Me4, here the five-membered
Sn3Se2 heterocycle adopts an envelope conformation
Fig. 6. 29Si-CP-MAS-NMR spectrum of the solid compound 2a
showing two different signals for the two crystallographically differ-
ent SiMe2 units and one for the central Si2Me2 unit.
,
and intermolecular Sn–Se contacts of 3.76–4.09 A are

144
U. Herzog et al. / Journal of Organometallic Chemistry 630 (2001) 139–148
These reactions are surprisingly clean, no other sili-
con containing by-products have been observed. These
reactions show again the high stability of five-mem-
bered rings in these systems even though heterocycles
with four silicon and one chalcogen atom are formed.
While we have already published the formation and
the molecular structure of the sulfur compound 5a, see
Fig. 9 [4], we now succeeded in the preparation of the
selenium (5b) and tellurium (5c) derivatives. The NMR
data of 5a–c are summarized in Table 7. Remarkable
are the relatively drastic changes of the 29Si-NMR
chemical shifts of the branching SiMe units from E=S
to E=Te even though the first coordination sphere at
these silicon atoms remains unchanged. As also ob-
served for other silselenanes and -telluranes [5,9] the
1
125Te-NMR parameters (l and JESi) follow the corre-
sponding 77Se-NMR data of the analogous selenium
compounds by a factor of 2.5–2.7.
3. Experimental
3.1. NMR and GC–MS measurements
Fig. 7. (a) 29Si-NMR chemical shifts of 2a as a function of tempera-
ture (−80 to +60 °C). (b) 1H-NMR chemical shifts of 2a as a
function of temperature (−80 to +60 °C).
All NMR spectra were recorded on a Bruker DPX
400 in CDCl3 solution and with TMS as internal stan-
1
dard for H, 13C and 29Si. External Me4Sn, Ph2Se2 (lSe
460 ppm) and Ph2Te2 (lTe 422 ppm) in CDCl3 were
used as standards for 119Sn, 77Se and 125Te.
In order to obtain a sufficient signal-to-noise ratio of
1
1
1,2
29Si-NMR spectra for resolving JSiC, JSiSi
J
,
J
or
SiSe
satellites 29Si INEPT spectra were also recorded.
observed [7]. On the other hand, no intermolecular
1,2
SiTe
77Se, 125Te and 119Sn spectra were determined using an
IGATED pulse program.
contacts are formed in the case of the five-membered
t
tin chalcogen heterocycles Bu2Sn(E)2Snt2Bu4 (E=S, Se,
t
Te). The bulky Bu substituents prevent such contacts,
Temperature dependent NMR spectra of 2a were
done in a solution of 60 vol% THF and 40 vol% CDCl3
force the five-membered ring into a planar (E=S) or
almost planar (E=Se) conformation and increase the
Sn–E bond lengths [8].
1
and TMS as internal standard. H- and 29Si-INEPT-
NMR spectra were taken over a temperature range
from −80 to +60 °C in steps of 10 °C.
29Si-CP-MAS-NMR spectra were recorded on a
Bruker MSL 300 using the CPCYCL pulse program,
spinning frequency 3000 Hz, contact time 5 ms, calibra-
tion with external Q8M8.
2.3. 3,7-Dichalcogena-1,2,4,5,6,8-hexasila-
bicyclo[3.3.0]octanes (5a–c)
A different class of silchalcogenanes is accessible
from the doubly branched hexasilane (ClMe2Si)2-
SiMeSiMe(SiMe2Cl)2:
Mass spectra were measured on a Hewlett–Packard
5971 (ionization energy 70 eV, column 30 m×0.25

U. Herzog et al. / Journal of Organometallic Chemistry 630 (2001) 139–148
145
Fig. 8. Intermolecular contacts between tin and selenium in 3c.
mm×0.25 mm, phenylmethylpolysiloxane, column tem-
perature 80 °C (3 min)/20 K min−1, He flow of 0.5 ml
min−1).
calculated with the polarized 6-31G* basis set for C, H
and Si [19,20] and with effective core potentials for Ge,
Sn and Se [21]. All structures were identified as true
local minima by their Hessian matrices.
3.2. Crystal structure analyses
3.4. Starting materials
X-ray structure analysis measurements were per-
formed on a Bruker SMART CCD. Crystal data of 2b,
2e and 3c as well as data collection and refinement
details are given in Table 8.
H2S, Se, Te, triethylamine, 1 M LiBEt3H in THF
(super hydride), Me2SiCl2, Me2GeCl2, Me2SnCl2,
Ph2SnCl2 were commercially available. Compound 1
[22], (CH2)5C(SH)2 [6] and (ClMe2Si)2Si2Me2(SiMe2Cl)2
[23] were prepared as described previously. THF was
distilled from sodium potassium alloy prior to use. The
other solvents were dried over KOH or sodium wire.
All reactions were carried out under argon applying
standard Schlenk techniques.
The unit cell dimensions were determined with the
program SMART [10]. For data integration and refine-
ment of the unit cell parameters the program SAINT [10]
was used. The space group was determined with the aid
of the programs XPREP [10] (2e and 3c) and ABSEN [11]
(2b). All data were corrected for absorption applying
SADABS [12]. The structures were solved using direct
methods (SHELX-97 [13] for 2e and 3c, SIR97 [14] for
2b), refined using least-squares methods (SHELX-97) and
drawn using ZORTEP [15]. The ellipsoids at the non-hy-
drogen atoms are at the 50% probability level. The
protons of the methyl groups in 2b could be located but
not refined to sufficient quality. They have been gener-
ated using the FIX 137 command. Because of the
mirror plane in 2b the hydrogen positions at C2, C4
and C5 are duplicated.
3.5. Preparation of R2M(S)2Si2Me2(S)2MR2 (2a–d)
(MR2=SiMe2, GeMe2, SnMe2, SnPh2)
In a typical experiment 2 mmol of the corresponding
dichloro compound (Me2SiCl2, Me2GeCl2, Me2SnCl2 or
Ph2SnCl2) was dissolved in 40 ml of hexane (or toluene
in the cases of the organotin chlorides) and 0.456 g (2
3.3. Theoretical methods
The ab initio molecular orbital calculations were
carried out using the GAUSSIAN 98 series of programs
[16]. Geometries were fully optimized at the DFT level,
using Becke’s three-parameter hybrid exchange func-
tional and the correlation functional of Lee et al.
(B3LYP) [17,18]. Geometry optimizations, harmonic
frequencies, and zero-point vibrational energies were
Fig. 9. Molecular structure of 5a [4].

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U. Herzog et al. / Journal of Organometallic Chemistry 630 (2001) 139–148
Table 7
NMR data (ppm, Hz) of the 3,7-dichalcogena-1,2,4,5,6,8-hexasilabicyclo[3.3.0]octanes E(Me2Si)2Si2Me2(SiMe2)2E (E=S, Se, Te (5a–c)
Table 8
Crystal data of 2b, 2e and 3c as well as data collection and refinement details
2b
2e
3c
Crystal system
Space group
Unit cell dimensions
Orthorhombic
Pnma
Triclinic
Orthorhombic
Pbcn
(
P1
,
a (A)
12.2673(9)
9.9225(8)
13.7735(10)
90
90
90
1676.5(2); 4
1.663
4.196
6.92390(10)
9.4610(2)
15.6112(3)
78.0530(10)
85.9290(10)
71.0050(10)
946.01(3); 2
1.330
9.81560(10)
14.2553(2)
13.1109(2)
90
90
90
1834.53(4); 4
2.533
10.762
,
b (A)
,
c (A)
h (°)
i (°)
k (°)
3
,
Volume (A ); Z
Dcalc. (g cm−3
Linear absorption coefficient
(mm−1
)
0.618
)
Radiation used
Mo–Ka
Mo–Ka
Mo–Ka
Temperature (K)
173(2)
173(2)
173(2)
Scan method
v scans
v scans
v scans
Absorption correction
Max/min transmission
Measured reflections
Independent reflections
Observed reflections
Rint
Empirical
Empirical
Empirical
0.519/0.487
6286
2517
2171
0.902/0.693
7668
5143
3792
0.119/0.052
13047
2715
2170
0.0206
0.0253
0.0516
q Range for collection (°)
Completeness to qmax (%)
Refinement method
Final R1 (I\2|(I))
R1 (all data)
2.22–30.69
1.33–30.67
2.52–30.84
91.9
88.0
93.9
Full-matrix least-squares on F2
Full-matrix least-squares on F2
Full-matrix least-squares on F2
0.0216
0.0270
0.0349
0.0591
0.0278
0.0405
H-locating and refining
DIFMAP
/
REFALL
DIFMAP
/
REFALL
DIFMAP/mixed
1.081
0.961/−1.079
Goodness-of-fit on F2
1.046
0.436/−0.899
1.007
0.381/−0.273
−3
,
Max/min e-density (e A
)
mmol) of compound 1 was added. With stirring, a
stream of dried H2S was passed through the solution
while 1.66 ml (12 mmol) of NEt3 was slowly added by
a syringe. A white precipitation of triethylammonium
chloride appeared immediately. After stirring for 1 h
the mixture was filtered and the solvent removed to
yield the bicyclo[3.3.0]octanes as a white crystalline
residue. The products were recrystallized from hot satu-
rated solutions in hexanes to give single crystals suit-
able for X-ray analysis.
2a: m.p. 75–77 °C, 2b: m.p. 127 °C, 2c: m.p. 184–
187 °C, 2d: m.p. 130 °C.
2a: GC–MS (m/e, rel. int.): 330 (M+, 36), 315
(Me5Si4S4, 26), 165 (Me3Si2S2, 100), 73 (Me3Si, 20).

U. Herzog et al. / Journal of Organometallic Chemistry 630 (2001) 139–148
147
2b: GC–MS: 420 (M+ (74Ge72Ge), 1.5), 405
(Me754Ge72GeSi2S4, 73), 301 (Me754GeSi2S3, 30), 211
(Me734GeSiS2, 100), 181 (Me74GeSiS2, 21), 165
(Me3Si2S2, 51), 135 (MeSi2S2, 10), 119 (Me734Ge, 36),
105 (Me3SiS, 24), 89 (Me74Ge, 16), 73 (Me3Si, 74). (The
isotopic patterns of all fragments fitted the natural
abundance of 70Ge:72Ge:73Ge:74Ge:76Ge=20.5:27.4:
7.8:36.5:7.8 [24].)
2c: Anal. Calc. for C6H18S4Si2Sn2: C, 14.07; H, 3.54;
S, 25.05; Found: C, 14.78; H, 3.59; S, 24.89%.
A molar ratio of Me2MCl2 to 1 of 1:1 instead of 2:1
was applied in order to prevent the formation of the
six-membered heterocycles (Me2MS)3 as by-products.
Under the reaction conditions excess 1 forms the tetra-
cyclic cage compound Me6Si6S6 [4], which is insoluble
in hexane and can therefore be removed together with
the ammonium salt by filtration.
As described for the selenium compounds a mixture
of 0.114 g (0.5 mmol) of 1 and 1 mmol of Me2MCl2
dissolved in 5 ml of hexane (or toluene in the case of
Me2SnCl2) was added to the Li2Te suspension. The
analogous work-up yielded the tellurium containing
bicyclo[3.3.0]octanes 4a–c as light yellow crystalline
residues which are extremely air sensitive and turn
black within seconds but are stable under argon at r.t.
for weeks.
3.8. 3,7-Dichalcogena-1,2,4,5,6,8-hexasilabicyclo[3.3.0]-
octanes (5a–c)
The preparation of 5a starting from the doubly
branched hexasilane, H2S and NEt3 has already been
described in Ref. [4]. The addition of 0.23 g (0.5 mmol)
of (ClMe2Si)2Si2Me2(SiMe2Cl)2 to a suspension of 1
mmol Li2Se or Li2Te (prepared as described above) and
work-up as described in Section 3.5 yielded the sele-
nium compound 5b as relatively low melting point
crystalline needles (m.p. 60 °C) and the tellurium
derivative 5c as a light yellow, extremely air sensitive
oil.
3.6. (CH2)5C(S)2Si2Me2(S)2C(CH2)5 (2e)
A total of 0.228 g (1 mmol) of compound 1 was
dissolved in 40 ml of hexane, 0.296 g (2 mmol) of
(CH2)2C(SH)2 and 0.55 ml (4 mmol) of NEt3 were
added under stirring. After 1 h the mixture was filtered
from the precipitated ammonium salt and the solvent
removed to yield 2e as colorless crystals without any
by-products. The product was recrystallized from hot
hexane, m.p. 130 °C.
5a: GC–MS (m/e, relative intensity): 382 (M+, 73),
367 (Me9Si6S2, 38), 323 (Me7Si5S2CH2, 32), 309
(Me7Si5S2, 61), 277 (Me7Si5S, 13), 249 (Me7Si4S, 19),
131 (Me5Si2, 16), 73 (Me3Si, 100), 59 (Me2SiH, 15).
5b: GC–MS: 478 (M+, 19), 463 (Me9Si680Se2, 15),
419 (Me7Si580Se2CH2, 9), 405 (Me7Si580Se2CH2, 13), 325
(Me7Si580Se, 14), 297 (Me7Si480Se,11), 267 (Me5Si480Se,
6), 239 (Me5Si380Se, 7), 159 (Me5Si3, 11), 131 (Me5Si2,
23), 73 (Me3Si, 100), 59 (Me2SiH, 12). (The isotopic
patterns of all fragments fitted the natural abundance
of 76Se:77Se:78Se:80Se:82Se=9.2:7.6:23.7:49.8:8.8 [24].)
3.7. Me2M(E)2Si2Me2(E)2MMe2 (3a–4c) (M=Si,
Ge, Sn; E=Se, Te)
3.7.1. Selenium compounds (3a–c)
A total of 0.16 g (2 mmol) of black selenium powder
was reacted with a mixture of 4 ml of a 1 M solution of
Li[BEt3H] in THF and an additional 5 ml of THF with
stirring. The selenium dissolved within a few seconds
with formation of a white suspension of Li2Se. A
mixture of 0.114 g (0.5 mmol) of 1 and 1 mmol of
Me2MCl2 dissolved in 5 ml of hexane (or toluene in the
case of Me2SnCl2) was added to the suspension. The
precipitation of Li2Se disappeared almost immediately.
After stirring for 30 min at room temperature (r.t.) the
solvents were removed in vacuo and replaced by 10 ml
of hexane. The solution was separated from precipi-
tated LiCl. Removal of the solvent produced 3a–c as
colorless crystalline powders. Crystals of 3c were grown
from toluene solution.
4. Supplementary material
Crystallographic data for the structural analysis have
been deposited with the Cambridge Crystallographic
Data Centre, CCDC no. 163663 for compound 2b,
CCDC no. 163664 for compound 2e and CCDC no.
163665 for compound 3c. 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).
3.7.2. Tellurium compounds (4a–c)
Acknowledgements
A total of 0.25 g (2 mmol) of tellurium powder (200
mesh) was added to a mixture of 4 ml of a 1 M solution
of Li[BEt3H] in THF and an additional 5 ml of THF
under stirring. After 5 min the tellurium started to react
with formation of a deep purple solution which became
dark red after 1 h at r.t.
The authors thank the Deutsche Forschungsgemein-
schaft for financial support. Special thanks are given to
the Computing Centre of the TU Bergakademie
Freiberg for supplying disk space and computing time.
Furthermore, the authors thank Prof. H. Lang, Chair

148
U. Herzog et al. / Journal of Organometallic Chemistry 630 (2001) 139–148
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