Syntheses and coordination chemistry of di-, tri-, and tetrastibanes, R2Sb(SbR′)nSbR2 (n=0, 1, 2)

Article abstract of DOI:10.1016/S0022-328X(03)00320-6

Syntheses of the stibanes, ^tBu₂Sb(SbMe) _nSb^tBu₂ [n = 1 (1), 2 (2)], (^tBu₂Sb)₂ (3), Mes₂ Sb(SbPh)_nSbMes₂ [n = 1 (4), 2 (5)] and of comp

Full text of DOI:10.1016/S0022-328X(03)00320-6

Journal of Organometallic Chemistry 677 (2003) 15ꢁ20
/
www.elsevier.com/locate/jorganchem
Syntheses and coordination chemistry of di-, tri-, and tetrastibanes,
R Sb(SbR?) SbR (nꢀ0, 1, 2)
/
2
n
2
Hans Joachim Breunig *, Ioan Ghesner, Mihaiela Emilia Ghesner, Enno Lork
Institut f u¨ r Anorganische und Physikalische Chemie, Universit a¨ t Bremen, Fachbereich 2, Postfach 330 440, D-28334 Bremen, Germany
Received 24 January 2003; received in revised form 11 March 2003; accepted 20 March 2003
Abstract
t
t
t
Syntheses of the stibanes, Bu
complexes with stibane ligands, [(CO)
8) (RꢀCH SiMe ) are reported. The crystal structures of 6 and 8 were determined by X-ray diffraction.
2003 Elsevier Science B.V. All rights reserved.
2
Sb(SbMe)
n
Sb Bu
2
[nꢀ
(6), [Cr(CO)
/
1 (1), 2 (2)], ( Bu
2
Sb)
2
(3), Mes
2
Sb(SbPh)
n
SbMes
2
[nꢀ
/
1 (4), 2 (5)] and of
5
Cr] (Me
2
2
Sb)
2
4
(Me Sb(SbR)
2
2
SbMe )] (7), [Cr(CO)
2
4
(Ph
2
SbꢀSbPhꢀ
/
/
SbRꢀSbPh )]
/
2
(
/
2
3
#
Keywords: Antimony; Chromium complexes; X-ray structure analyses
1
. Introduction
formation and structures of complexes with di- and
tetrastibane ligands.
Organometallic compounds with antimonyꢁ
mony single bonds are well known as distibanes,
R Sb) and cyclostibanes, (RSb) (nꢀ3ꢁ6) [1]. Much
/
anti-
(
/
/
2. Results and discussion
2
2
n
less developed is the chemistry of catena-stibanes,
R(nꢂ2)Sbn that are of interest as one-dimensional
substances [2]. Previously known examples [3,4] of
catena-stibanes are ill-defined polymers or components
of ring-chain equilibria (Eq. (1)).
2.1. Syntheses of sterically protected stibanes
Tri- and tetrastibanes bearing terminal tert-butyl
t
groups form by reduction of Bu SbCl and MeSbCl
2
2
(
(
2:1 molar ratio) with magnesium in tetrahydrofuran
t
Eq. (2)). The novel catena-stibanes, Bu Sb(Sb-
cyclo-(SbR?) ꢂR SbꢀSbR
n
2
2
2
Xcatena-R Sbꢀ(SbR?) ꢀSbR
(1)
t
2
n
2
Me) Sb Bu [nꢀ
/1 (1), 2 (2)] are obtained as an yellow
n
2
air sensitive liquid which is readily soluble in organic
solvents. The tristibane 1 which corresponds to the
stoichiometry of the reagents is formed in 30% yield.
The unexpected formation of 2 (13%) is probably related
to the sterically less congested situation in this tetra-
stibane. The remaining products of the reduction are
brown solids which are insoluble in hydrocarbons. They
probably contain highly polymeric congeners of 1 and 2.
ꢀ
Recently we were able to trap and to fully characterize
the first tetrastibanes as ligands in chromium carbonyl
complexes [4]. The phosphorus analogues of catena-
stibanes have received more attention and several well
defined examples [5,6] and also complexes with catena-
phosphane or -arsane ligands [7,8] were reported.
Famous extended one-dimensional systems are the
ladder structure of methyl arsenic [9] and the linear
chains of tetramethyldistibane [10]. We report here on
the protection of catena-tri- and tetrastibanes by bulky
ꢂMeSbCl ꢂMg=THF; 25
C
2
R SbCl
R Sb(SbMe) SbR
(2)
2
2
n
2
ꢃMgCl2
t
organic groups ( Bu, Mes, Me SiCH ) and on the
3
t
2
where Rꢀ
/
Bu; 1: nꢀ
/
1; 2: nꢀ
/2.
Attempts to separate 1 and 2 by column chromato-
graphy or other methods led to decomposition. The
1
novel catena-stibanes were identified by their H-NMR
*
18-4042.
Corresponding author. Tel.: ꢂ
/
49-421-218-2266; fax: ꢂ49-421-
/
2
0
E-mail address: breunig@chemie.uni-bremen.de (H.J. Breunig).
spectra in C D (Fig. 1a). For each stibane there are
6
6
022-328X/03/$ - see front matter # 2003 Elsevier Science B.V. All rights reserved.
doi:10.1016/S0022-328X(03)00320-6

16
H.J. Breunig et al. / Journal of Organometallic Chemistry 677 (2003) 15ꢁ20
/
1
ment of the H-NMR signals. The high reactivity of the
novel catena-stibanes is also reflected in the mass
spectra, which show signals for fragment ions of 1 and
for various decomposition products.
In other approaches for the syntheses of catena-
t
stibanes with terminal Bu Sb groups we also investi-
2
t
gated the reactions of [( Bu Sb) Sb][K(pmdeta)]
2
2
(
pmdetaꢀ
/
pentamethyldiethylenetriamine) [11] with
80
30 8C. We were able to prove the formation of 1
MeI or Me SiCH Cl in THF or toluene between ꢃ
and ꢃ
and a rearrangement product, Bu Sb CH SiMe by
NMR methods, and mass spectrometry but found that
the reactions were not useful for synthetic purposes.
Also reactions of cyclostibanes, (RSb) (Rꢀ
CH SiMe , nꢀ4, 5) with ( Bu Sb) (3) were investigated
/
3
2
/
t
3
2
2
3
t
/
Bu, Rꢀ
/
n
t
/
2
3
2 2
in NMR tube experiments in C D . At room tempera-
6
6
ture no reaction occurred even with excess of 3. Heating
the solutions leads to decomposition of the distibane
reagent. The synthesis of 3 was achieved in 83% yield
and high purity in a new way simply by adding
t
Bu SbCl to LiAlH . The reverse procedure (i.e. addi-
2
4
t
t
tion of LiAlH4 to Bu SbCl) gives Bu SbH [12].
2
2
Previously reported methods for the preparation of 3
12,13] are more complicated and we found it difficult to
obtain a pure product.
[
Catena-tri- and tetra-stibanes exist also with mesityl
substituents in terminal positions. Reaction of
Mes SbLi with PhSbCl at ꢃ70 8C in a 2:1 stoichiome-
/
2
2
1
Fig. 1. H-NMR spectra of 1 (ꢄ
/
6 6
) and 2 (m) in C D ; above: a fresh
try (Eq. (3)) gives 4 in 16% together with 5 in 4% yield.
The remaining products are insoluble materials, prob-
ably polymeric arylstibanes.
sample; below: sample after 1 day at room temperature with formation
t
of Bu SbMe (") and other products.
2
ꢀ
three characteristic signals, a pair of singlet signals of
t
equal intensity for the diastereotopic Bu groups and
ꢂPhSbCl =THF; ꢃ70
C
2
Mes SbLi
Mes Sb(SbPh) SbMes
2 n 2
2
ꢃLiCl
singlet signals for the methyl groups.
Separate signals for the meso- and d, l form of the
tetrastibane 2 were not observed. Most likely only one
of the isomers is present in solution. In an alternative
explanation the inversion of configuration at the central
antimony atoms might be assumed. This process is
however unlikely to be fast at the NMR time scale. 1
and 2 are the first catena-stibanes which exist in solution
in the absence of di- and cyclo-stibanes. The sterical
(3)
where 4: nꢀ
/
1; 5: nꢀ2
/
Compounds 4 and 5 are air sensitive, but stable in an
inert atmosphere at room temperature for several days.
1
The H-NMR spectra show the characteristic pattern
for the diastereotopic mesityl groups of the peripheral
Mes Sb unit, i.e. three sets of two singlets for the ortho
methyl protons, para methyl protons and for the meta
protons for each compound. In the EI mass spectra the
2
t
influence of the Bu groups is sufficient to protect the
terminal Sbꢀ
/
Sb bonds and also to disfavour the
t
formation of ( Bu Sb) (3) during the syntheses. Despite
ꢂ
decomposition product Mes PhSb was identified.
2
2
2
Also the dehalogenation of a mixture of (Me3-
SiCH ) SbBr and MeSbCl with magnesium at room
temperature leads orange soluble products and black
solids. The former probably consist of tri- and tetra-
the sterical protection 1 and 2 are not stable at room
temperature for a long time. They decompose in the
course of hours with migration of methyl groups and
2
2
2
t
formation of Bu SbMe and other products. This
2
stibanes, catena-R Sb(SbMe) SbR (nꢀ
/
1, 2; Rꢀ
/
2
n
2
1
decomposition can be followed in the H-NMR spectra
CH SiMe ), the latter of polymeric stibanes. However,
2
3
t
where the two singlets assigned to Bu SbMe become
2
the sterical protection of the oligo stibanes by terminal
trimethylsilylmethyl groups is not sufficient and decom-
position occurs already during the work-up procedures
SbR (RꢀCH SiMe ) [14] and
a black polymeric form of methylantimony, (MeSb)x
the most intense signals after 1 day. The spectra (Fig. 1)
show that the sterically more congested tristibane 1
decomposes faster than 2. The varying 1:2 ratio during
the decomposition confirms unambiguously the assign-
with formation of R Sbꢀ
/
/
2
2
2 3

H.J. Breunig et al. / Journal of Organometallic Chemistry 677 (2003) 15ꢁ
/
20
17
[15]. In Eq. (4) features a new synthetic path for this
interesting material.
bane studied by X-ray crystallography. The coordina-
tion of the distibane leads to wider angles and shorter
bonds at the antimony atoms (Me Sb /6: SbC 92.2ꢁ
/
4
2
2
9
5.28/99.2(18)ꢁ
/
100.34(16)8,
CSbSb
Sb 2.84/2.8097(9) A). These
94.27ꢁ94.658/
/
˚
9
6.41(11)ꢁ102.44(11)8; Sbꢀ
/
/
changes of the geometry probably result from an
3
increase of s-orbital participation from the p config-
ð4Þ
uration of the antimony atoms in Me
3
4
Sb
2
to closer to
Cr (2.625 A) distances in 6 compare
˚
sp in 6. The Sbꢀ
/
˚
well with those found in 7 (Sbꢀ
unusual feature of 6 is a substantial deviation (dihedral
angle lp-SbꢀSb-lpꢀ1608, lpꢀlone pair of electrons at
Sb) from the ideal antiperiplanaric (trans) conformation
Sb-lpꢀ1808) which was found in solid Me Sb
10] and [(CO) M] (Ph Sb) (Mꢀ
/Cr 2.6087 A [4]). An
2
.2. Complexes with stibane ligands
For the study of the role of the organic groups in the
chemistry of catena-stibanes it is useful to compare
compounds with reverse positions of the organic sub-
stituents. Tri- and tetrastibanes with terminal methyl-
/
/
/
(
lp-Sbꢀ
/
/
4
2
[
/
Cr [17], W [18]) Table
5
2
2
2
1
.
The formation of 7 is remarkable because the tetra-
stibane is only a minor component in the initial stibane
and
central
trimethylsilylmethyl-groups,
i.e.
CH SiMe ) were
Me Sb(SbR) SbMe (nꢀ
found only in equilibria with Me Sbꢁ
/
3, 4; Rꢀ
/
2
n
2
2
3
mixture and also because Cr(CO) units do not form
4
/
SbMe2 and
2
easily from [THFCr(CO) ] at low temperatures. In fact
5
cyclo-(RSb) (nꢀ4, 5). After successfully trapping the
/
n
tetrastibane from the equilibrium mixture we tried to
isolate also the tristibane by complexation and reacted
Table 1
Crystallographic data and measurements for 6×
/C
6
H
6
and 8
the equilibrium mixture with [THFCr(CO) ] in THF.
5
However instead of the formation of a tristibane
complex, the coordination of the distibane and the
tetrastibane occurred and [(CO) Cr] (Me Sb) (6) [16]
Compound
6×
/
C
6
H
6
8
Empirical formula
C
C
14
H
12Cr
2
O
10Sb×
/
4 4
C38CrH36O Sb Si
5
2
2
2
6
H
6
and
CH SiMe ) (7) [4] were obtained in 60 and 8% yield.
cyclo-[Cr(CO) Me Sb(SbR) SbMe ]
(Rꢀ
/
4
2
2
2
Formula weight
Colour
765.84
Yellow
1123.76
Orange
2
3
Crystal size, (mm)
Unit cell dimensions
0.5ꢄ
/
0.35ꢄ
/
0.3
0.5ꢄ
/
0.4ꢄ0.3
/
The structure of the distibane complex was determined
by an X-ray diffraction study on single crystals of 6×
C H . The molecular structure is depicted in Fig. 2. 6 is
/
˚
a (A)
15.233(3)
11.556(2)
16.73(3)
90
11.27(2)
12.549(3)
15.296(3)
83.94(3)
72.60(3)
81.63(3)
triclinic
6
6
˚
b (A)
the first transition metal complex of tetramethyldisti-
˚
c (A)
a (8)
b (8)
g (8)
Crystal system
Space group
Z
107.15(3)
90
monoclinic
¯
P1
1
P2 /c
/
4
2
Diffractometer
˚
stoe IPDS
0.71073
173(2)
39 116
5486
stoe IPDS
0.71073
173(2)
29 045
7379
/
a
MoꢁK (A)
Temperature (K)
Reflections collected
Independent reflections
R
int
0.0455
98.2
0.0525
92.9
Completeness to u (%)
Absorptions coefficient
2.696
2.940
ꢃ1
(
mm
)
Absorption correction
DIFABS
DIFABS
a
Final R indices
R
1
ꢀ/
0.0254
R
1
ꢀ
/
0.0216
0.0431
0.0343,
0.0450
[
I ꢀ
/
2s(I)]
R indices (all data)
wR
2
ꢀ
/
0.0669
wR
2
ꢀ
/
a
R
1
ꢀ/
0.0325,
R
1
ꢀ
/
wR
1.010
5486/0/343
0.66
2
ꢀ
/0.069
wR
0.883
7379/0/452
0.636, ꢃ0.498
2
ꢀ
/
2
Fig. 2. ORTEP-like representation at 50% probability of 6 showing the
Goodness-of-fit on F
Data/restraints/parameters
˚
atomic numbering scheme. Selected distances (A) and angles (8):
Sb(1)ꢀSb(2) 2.8097(9), Sb(1)ꢀC(1) 2.132(4), Sb(1)ꢀC(2) 2.150(4),
Sb(2)ꢀC(3) 2.141(3), Sb(2)ꢀC(4) 2.135(3), Sb(1)ꢀCr(1) 2.629(9),
Sb(2)ꢀCr(2) 2.621(8), C(1)ꢀSb(1)ꢀC(2) 99.20(18), C(3)ꢀSb(2)ꢀC(4)
00.34(16), Sb(1)ꢀSb(2) 122.39(3), Cr(2)ꢀSb(2)ꢀSb(1)
Cr(1)ꢀ
18.33(2).
/
/
/
Largest difference peak and 1.051, ꢃ
˚
hole (e A
/
/
ꢃ3
/
/
/
)
/
/
/
/
/
a
Definition of the
2
R
values:
R
1
ꢃ1
ꢀ
ꢀ
/
SjjF
0
ꢃ
/
jF
c
jj/SjF
0
j; wR
2
ꢀ/
1
1
/
/
/
/
2
2
2
2
1/2
]} with w
2
2
2
{
[wS(F
/
/
ꢃ
/
F
/
)/
]/S[w(F
/
)/
/
s (F )ꢂ
/
/
/(aP) ꢂbP.
/
0
c
0
0

18
H.J. Breunig et al. / Journal of Organometallic Chemistry 677 (2003) 15ꢁ20
/
3
3
˚
[
efficient for trapping the tetrastibanes.
In a re-examination of the synthesis of cyclo-
nbdCr(CO) ] (nbdꢀ
/
norbornadiene) is much more
2.183(3) A) correspond to sp hybridization and p
configurations, respectively, for the four- and three-
Sb bond
4
coordinate antimony atoms. The average Sbꢀ
/
[
Cr(CO) (Ph Sbꢀ
/
SbRꢀ
/
SbRꢀ
/
SbPh2)] (Rꢀ
/
CH SiMe )
2
distance of 2.8409 A˚ is consistent with normal single
bonds. A remarkable feature of the crystal structure of 8
is the pair wise association of two enantiomers through
4
2
3
from cyclo-(Me SiCH Sb) (nꢀ
/
4, 5), (Ph Sb)2 and
2
3
2
n
[
nbdCr(CO) ] [4] we have isolated cyclo-[Cr(CO) -
4
4
(
Ph Sbꢀ
/
SbPhꢀ
/
SbRꢀ
/
SbPh )] (Rꢀ
/
CH SiMe ) (8), an
3
˚
a short intermolecular contact (3.636 A) between the
Sb(2) atoms which bear parallel phenyl groups. Close
2
2
2
interesting side product formed by migration of sub-
stituents. This novel complex contains the first tetra-
stibane ligand with two different chiral antimony centers
and where four optical isomers are possible. An X-ray
diffraction study revealed that only two isomers, the
enantiomers of the threo form are present in crystals of
intermolecular Sb
/
ꢁ ꢁ ꢁ
/
Sb contacts were observed repeat-
edly in crystal structures of distibanes, cyclostibanes, or
complexes with cyclo-Sb ligands [19]. They usually lead
3
to extended arrays. Dimeric association is a new
phenomenon which is favored in the case of 8 because
with exception of Sb(2) all the antimony atoms are
sterically shielded.
The present results mark two important steps in the
development of catena-stibane chemistry: (i) the first
antimony compound with two different Sb chiral centers
was isolated and (ii) tri- and tetrastibanes which are not
components of ring chain equilibria (Eq. (1)) were
synthesized and characterized in solution. However for
further progress the thermal stability of the catena-
8
. The structure (Fig. 3) features a five membered
chelate ring where the Sb(2)ꢀSb(3) unit is twisted by
Sb(4) plane.
Cr bond lengths in 8 (2.6109(11), 2.6065(11)
/
2
38 out of the Sb(1)ꢀ
The Sbꢀ
/
Crꢀ
/
/
˚
˚
Cr 2.596(8), 2.588(8) A in 7
4]). The angles around the antimony atoms (Sb(1)
A) lie in the usual range (Sbꢀ
/
[
9
6.94(13)ꢁ
3.70(1)ꢁ95.82(1); Sb(3) 91.94(1)ꢁ
C bond lengths (four-coordinate Sbꢀ
/
116.66(1); Sb(4) 95.86(1)ꢁ
97.22(4)8) and the
C 2.14(3)ꢁ
2.175(3)ꢁ
/116.49(1); Sb(2)
9
/
/
Sbꢀ
2
/
/
/
˚
A
.15(3)
and three-coordinate Sbꢀ
/
C
/
Fig. 3. ORTEP-like representation at 50% probability of (S,S)-8 and (R,R)-8, showing the dimeric association and atom numbering scheme for
˚
(
S,S)-8. Selected distances (A) and angles (8): Sb(1)ꢀ
Sb(4)ꢀC 2.140(3)ꢁ2.144(4), Sb(2)ꢀC(31) 2.175(3), Sb(3)ꢀ
1.62(3), C(31)ꢀSb(2)ꢀSb(3) 93.7(1), Sb(2)ꢀSb(1)ꢀCr(1) 120.79(3), C(41)ꢀ
1.94(1), Sb(1)ꢀSb(2)ꢀSb(3) 95.16(3), CꢀSb(4)ꢀSb(3) 95.86(1)ꢁ105.3(1), Cꢀ
Sb(4) 97.22(4), C(51)ꢀSb(4)ꢀC(61) 98.88(14), C(31)ꢀSb(2)ꢀSb(1) 95.82(1).
/
Sb(2) 2.8609(1), Sb(2)ꢀ
C(41) 2.183(3), Sbꢀ
Sb(3)ꢀ
Sb(1)ꢀ
/
Sb(3) 2.8207(11), Sb(3)ꢀ
Cr 2.6065(11)ꢁ2.6109(11), Sb(2)
Sb(2) 95.92(11), Sb(3)ꢀSb(4)ꢀ
Sb(2) 99.08(9)ꢁ103.31(1), C(11)ꢀ
/
Sb(4) 2.8411(8), Sb(1)ꢀ
ꢁ ꢁ ꢁSb(2a) 3.636, Sb(1)ꢀ
Cr(1) 121.89(3), C(41)ꢀ
Sb(1)ꢀ
/
C 2.149(3)ꢀ
Cr(1)ꢀ
Sb(3)ꢀ
/
2.150(3),
/
/
/
/
/
/
/
/
/
/
Sb(4)
Sb(4)
9
9
/
/
/
/
/
/
/
/
/
/
/
/
/
/
/
/
/
/
/
/
C(21) 96.94(13), Sb(2)ꢀ
/
Sb(3)ꢀ
/
/
/
/
/

H.J. Breunig et al. / Journal of Organometallic Chemistry 677 (2003) 15ꢁ
/
20
19
stibanes should be increased by choosing less mobile
substituents.
3.3. catena-Mes Sb(SbPh) SbMes (4: nꢀ
/
1, 5: nꢀ
/
2)
2
n
2
A solution of 0.28 g (1.0 mmol) PhSbCl in 60 ml of
2
THF was added dropwise to a solution of 0.82 g (2.3
mmol) Mes SbLi in 40 ml THF at ꢃ
/
70 8C. The solution
2
3
. Experimental
mixture was stirred 1 h at ꢃ70 8C and then allowed to
/
warm slowly to r.t. Thereafter, the solvent was removed
in vacuo and the residue extracted with 100 ml of
petroleum ether. The orange petroleum ether solution
NMR spectra were run on a Bruker DPX 200
spectrometer. Chemical shifts are reported in d units
1
(
ppm) referenced to C D H (7.15 ppm, H) and C D
6 5 6 6
was reduced to 10 ml, combined with Al O (1 g), dried
2
1
128.0 ppm, C). Mass spectra were recorded on
3
3
(
to a flowing powder under reduced pressure and placed
Finnigan MAT CH7 (A) and Finnigan MAT 8222
spectrometers. The pattern of antimony-containing
ions was compared with theoretical values. The reac-
tions and manipulations were performed in an inert
atmosphere of dry argon. (Me SiCH ) SbBr [20],
on a chromatography column (8ꢄ2 cm, Al O , activity
level II). With petroleum ether/toluene (16/4) an orange
broad fraction was eluted. Removal of the solvent gives
/
2
3
0.2 g of a mixture of 16% of catena-Mes SbSb(Ph)-
SbMes and 4% of catena-Mes Sb(Sbh) SbMes as an
2
3
2 2
2
2
2
2
MeSbCl [21], PhSbCl [22] and Mes SbLi [23] were
2
1
orange oil. H-NMR (C D , 200 MHz): catena-
2
2
6
6
prepared according to reported procedures.
Mes Sb(SbPh) SbMes : 2.03 (s, 6H, CH -p), 2.12 (s,
2
2
2
3
6
6
H, CH -p), 2.29 (s, 12H, CH -o), 2.54 (s, 12H, CH -o),
3 3 3
t
t
.62 (s, 4H, C H -m), 6.77 (s, 4H, C H -m), 6.98ꢁ
/7.10
3
.1. catena- Bu Sb(SbMe) Sb Bu (1: nꢀ
/
1, 2: nꢀ
/2)
6
2
6
2
2
n
2
(m, 6H, SbC H -mꢂ
/
p), 7.40ꢁ
/
7.45 (m, 4H, SbC H -o).
6
5
6
5
t
.93 g (18.15 mmol) Bu SbCl in 25 ml THF and 1.89
catena-Mes SbSbPhSbMes : 2.06 (s, 6H, CH -p), 2.10
3
4
2
2
2
g (9.08 mmol) MeSbCl2 in 15 ml THF were added
simultaneously making use of two dropping funnels to
(s, 6H, CH
o), 6.65 (s, 4H, C
7.10 (m, 3H, SbC
SbC -o). MS (EI, 70 eV, 136 8C): 436 (46) [Mes -
2
3
-p), 2.32 (s, 12H, CH
3
-o), 2.47 (s, 12H, CH -
3
H
-m), 6.73 (s, 4H, C
H
-m), 6.98ꢁ
/
6
2
6
2
0
.5 g (20.83 mmol) Mg filings and the mixture was
6
H
5
-mꢂp), 7.65ꢁ7.70 (m, 2H,
/
/
stirred for 5 h at room temperature (r.t.). Removal of
the solvent in vacuo and extraction of the brown residue
6
H
5
ꢂ
ꢂ
ꢂ
PhSb ], 359 (10) [Mes Sb ], 316 (58) [MesPhSb ], 195
ꢂ
2
ꢂ
ꢂ
with 4ꢄ/120 ml petroleum ether gave an orange solu-
(100) [MesSb ], 119 (66) [Mes ], 77 (16) [Ph ].
tion. Evaporation of the solvent gave 2.56 g of an
1
orange oil containing 30% of 1 and 13% of 2. H-NMR
(
CCH ), 1.53 (s, 18 H, CCH ). 2: 1.35 (s, 6H, SbCH ),
C D , 200 MHz), 1: 1.05 (s, 3H, SbCH ), 1.46 (s, 18 H,
6 6 3
3
.4. Reaction of MeSbCl and R SbBr with Mg (Rꢀ
/
2
2
3
3
3
CH SiMe )
2
3
1
.42 (s, 18 H, CCH ), 1.51 (s, 18 H, CCH ). MS (EI, 70
3 3
t
ꢂ
t
ꢂ
eV, 100 8C): 550 (4) [ Bu MeSb ], 472 (1) [ Bu Sb ],
3
3
4
2
To 0.35 g (14.58 mmol) magnesium filings activated
with 0.5 ml 1,2-dibromomethane were added simulta-
t
30 (7) [ Bu MeSb ], 388 (1) [ Bu Me Sb ], 374 (3)
ꢂ
t
ꢂ
4
[
3 2 2 2 2
t
ꢂ
ꢂ
t
ꢂ
Bu MeSb ], 259 (6) [MeSb ], 194 (2) [ BuMeSb ],
2 2 2
neously 5.43 g (14.44 mmol) (Me SiCH ) SbBr in 35 ml
3
t
ꢂ
ꢂ
t
ꢂ
2 2
1
79 (2) [ BuSb ], 151 (2) [Me Sb ], 57 (100) [ Bu ].
2
THF and 1.5 g (7.21 mmol) MeSbCl in 15 ml THF
2
making use of two dropping funnels. The reaction
mixture was stirred for 2 h at r.t. until the magnesium
had reacted. Thereafter, the solvent was removed in
vacuo and the black remaining product mixture was
t
t
Sb Bu (3)
3
.2. Bu Sbꢀ
/
2
2
t
A solution of 3.6 g (13.26 mmol) of Bu SbCl in Et O
2
2
washed with 3ꢄ100 ml petroleum ether, giving an
/
(
suspension of LiAlH (0.55 g, 14.47 mmol) in Et O (30
70 ml) was added dropwise to a cold (ꢃ
/
80 8C)
orange solution. During the extraction from the orange
petroleum ether solution a black solid product precipi-
tate and the solution becomes yellow. 2.77 g (65%) of a
4
2
ml). The mixture was warmed to ꢃ
at this temperature and 1 h at ꢃ
then filtered through a cooled (ꢃ
/
50 8C, stirred for 2 h
/
30 8C. The solution was
30 8C) frit covered
/
yellowꢁ
obtained.
SiCH Sb]
with A: 0.67, B: 0.97 (8 H, CH
70 eV, 238 8C) black product: 546 (1.75) [Me Sb ], 531
4 4
/
orange oil and 0.31 g of a black powder was
1
with kieselguhr. Removal of the solvent under reduced
pressure (20 mbar) gave 2.6 g (83%) of 3 as a yellow
solid, decomposing above 7 8C. Attempts were made to
H-NMR (C
: 0.17 (s, 36 H, (CH )
3 3
6
D
6
,
200 MHz): [(Me
Si), AB spin system
13 Hz). MS (EI,
3
-
)
2
2
2
2
, JHH
ꢀ
/
2
ꢂ
grow single crystals from THF or Et O solutions but
2
1
only amorphous solids were obtained. H-NMR (C D ,
ꢂ
ꢂ
ꢂ
(1.5) [Me
395 (69) [Me
289 (34) [Me
Sb
], 501 (1.8) [MeSb
], 410 (100) [Me
], 304 (62) [Me
Sb
Sb
],
6
6
3
4
4
3
3
1
00 MHz): 1.36 (s, 36 H, CH3). C-NMR (C D , 200
3
ꢂ
ꢂ
ꢂ
2
2
2
Sb
3
], 365 (54) [Sb
ꢂ
3
4
],
6
6
ꢂ
MHz): 22.27 (s, CMe ), 23.85 (s, CH ). MS (CI ,
neg
3
Sb
], 274 (19) [Me Sb ], 259 (26)
2 2 2
3
3
t
ꢃ
4
t
ꢃ
2
ꢂ
ꢂ
ꢂ
NH , 36 8C): 658 (25) [ Bu Sb ], 415 (30) [ Bu Sb ],
[MeSb ], 244 (20) [Sb ], 166 (11) [Me Sb ], 151
2 2 3
3
3
3
t
59 (100) [ Bu Sb ].
ꢃ
ꢂ
3
(100) [Me Sb ].
2
2
2

20
H.J. Breunig et al. / Journal of Organometallic Chemistry 677 (2003) 15ꢁ20
/
3
.5. cyclo-[Cr(CO) (Ph Sbꢀ
/
SbPhꢀ
/
SbRꢀ/SbPh )]
2
Acknowledgements
4
2
(
Rꢀ
/
CH SiMe ) (8)
2
3
We thank Prof. Dr C.S. Silvestru from the Babes-
Bolyai University in Cluj-Napoca, Romania for helpful
discussions and the University Bremen for financial
support.
The reaction of a mixture of 0.37 g (0.35 mmol)
Me SiCH Sb) and 0.49 g (0.88 mmol) (Ph Sb) with
(
3
2
5
2
2
0
.22 g (0.88 mmol) [nbdCr(CO) ] in 20 ml of toluene and
4
the work-up procedures were performed as already
reported [4]. However, the separation of the reaction
products by column chromatography (Al O , activity
References
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/
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121 123
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6
6
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6
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/
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2
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[
C H -mꢂ
/p), 134.15, 134.52, 134.74, 135.14 (s, C H -
5
6
5
6
(
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2
20.40 (s, CO ), 221.39 (s, CO ), 233.98 (s, CO ). MS
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ꢂ
ꢂ
(
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(
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4 2 4 2
ꢂ
4
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ꢂ
[
ꢂ
ꢂ
[
Ph SbCr ], 275 (60) [Ph Sb ], 154 (100) [Ph ], 135
2 2 2
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ꢂ
ꢂ
(
35) [PhSi(CH ) ], 77 (29) [Ph ], 52 (17) [Cr ]. IR
3 3
toluene): 2279 s, 2002 vs, 1907 vs cmꢃ1 (n(CO)).
(
1
55.
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[
4
[
[
[
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4
. Supplementary material
Crystallographic data have been deposited with the
Cambridge Crystallographic Data Center, CCDC-
C H and CCDC-201826 for
[
[
20] D.G. Hendershot, A.D. Berry, J. Organomet. Chem. 449 (1993)
1
21] H. Althaus, Ph.D. Thesis, Universit a¨ t Bremen, 2000.
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2
compound 8. Copies of this information can be obtained
01825 for compound 6×
/
6
6
[22] N. Nunn, D.B. Sowerby, D.M. Wesolek, J. Organomet. Chem.
251 (1983) C45.
free of charge from: The Director, CCDC, 12 Union
[
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http://www.ccdc.cam.ac.uk).
/
44-1223-
3
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