Synthesis and characterization of three homoleptic bismuth silanolates: [Bi(OSiR3)3] (R = Me, Et, iPr)

Article abstract of DOI:10.1002/zaac.200500264

The bismuth tris(triorganosilanolates) [Bi(OSiR₃)₃] (1, R = Me; 2, R = Et; 3, R = iPr) were prepared by reaction of R ₃SiOH with [Bi(OtBu)₃]. Compound 1 crystallizes in the triclinic space group P1 with Z = 2 and the lattice constants a = 10.323(1) A, b = 13.805(1) A, c = 21.096(1) A and α = 91.871(4)°, β = 94.639(3)°, γ = 110.802(3)°. In the solid state compound 1 is a trimer as result of weak intermolecular bismuth-oxygen interactions with Bi-O distances in the range 2.686(6)-3.227(3) A. The coordination at the bismuth atoms Bi(1) and Bi(3) is best described as 3+2 coordination whereas Bi(2) shows a 3+3 coordination. The intramolecular Bi-O distances fall in the range 2.041(3)-2.119(3) A. Compound 3 crystallizes in the orthorhombic space group Pbcm with Z = 4 and the lattice constants a = 7.201(1) A, b = 23.367(5) A and c = 20.893(1) A, whereas the triethylsilyl-derivative 2 is liquid. In contrast to [Bi(OSiMe₃) ₃] (1) compound 3 is monomeric in the solid state, but shows similar intramolecular Bi-O distances in the range 1.998(2)-2.065(5) A. The bismuth silanolates are highly soluble in common organic solvents and strongly moisture sensitive. Compound 1 shows the lowest thermal stability.

Full text of DOI:10.1002/zaac.200500264

Synthesis and Characterization of Three Homoleptic Bismuth Silanolates:
Bi(OSiR ) ] (R ؍ Me, Et, iPr)
[
3
3
Sanna Paalasmaa, Dirk Mansfeld, Markus Schürmann and Michael Mehring*
Dortmund, Fachbereich Chemie der Universität
Received June 3rd, 2005.
Abstract. The bismuth tris(triorganosilanolates) [Bi(OSiR
R ϭ Me; 2, R ϭ Et; 3, R ϭ iPr) were prepared by reaction of
SiOH with [Bi(OtBu) ]. Compound 1 crystallizes in the triclinic
space group P1 with Z ϭ 2 and the lattice constants a ϭ
3
)
3
] (1,
space group Pbcm with Z ϭ 4 and the lattice constants a ϭ
˚
˚
˚
7.201(1) A, b ϭ 23.367(5) A and c ϭ 20.893(1) A, whereas the trie-
thylsilyl-derivative 2 is liquid. In contrast to [Bi(OSiMe ] (1) com-
R
3
3
3 3
)
¯
pound 3 is monomeric in the solid state, but shows similar intramo-
˚
˚
˚
˚
10.323(1) A, b ϭ 13.805(1) A, c ϭ 21.096(1) A and Ͱ ϭ 91.871(4)°,
lecular BiϪO distances in the range 1.998(2)Ϫ2.065(5) A. The bi-
β ϭ 94.639(3)°, γ ϭ 110.802(3)°. In the solid state compound 1 is
smuth silanolates are highly soluble in common organic solvents
and strongly moisture sensitive. Compound 1 shows the lowest
thermal stability.
a trimer as result of weak intermolecular bismuth-oxygen interac-
˚
tions with BiϪO distances in the range 2.686(6)Ϫ3.227(3) A. The
coordination at the bismuth atoms Bi(1) and Bi(3) is best described
as 3ϩ2 coordination whereas Bi(2) shows a 3ϩ3 coordination.
The intramolecular BiϪO distances fall in the range
Keywords: Bismuth; Silanolate; Crystal structure; Coordination
Compound
˚
2.041(3)Ϫ2.119(3) A. Compound 3 crystallizes in the orthorhombic
Introduction
anolate) is probably one of the most promising candidates
with respect to materials synthesis. Its preparation via met-
athesis reaction of BiCl with NaOSiMe was already re-
Metal alkoxides have found numerous applications as precur-
sors for metal oxide-based materials prepared via the sol gel
process or via chemical vapor deposition [1]. In contrast, me-
tal silanolates as precursors for materials have received less
attention, although their potential for materials synthesis was
recognized more than three decades ago and a large number
of metallasiloxanes were studied e.g. as model compounds
for silicate materials [2, 3]. However, it was demonstrated
only recently that metal silanolates are promising molecular
precursors for metal oxide and metal silicate nanoparticles
as well as mixed metal oxide materials prepared under mild
conditions [4]. Homoleptic heavy metal derivatives of the
type [M(OSiR ) ] (M ϭ Sn, Pb, Hg; R ϭ Me, Ph) are of
3
3
ported in 1968 by Schmidbaur [5]. However, difficulties to
obtain analytically pure [Bi(OSiMe ) ] were described. Our
3
3
attempts to prepare this compound through the salt-elimin-
ation method failed and gave sodium bismuth oxoclusters
instead [14]. Previously, we reported on the synthesis of
bismuth silanolates by reaction of the readily available
[
Bi(OtBu) ] with the corresponding triorganosilanol [11, 12].
3
This route precludes the incorporation of sodium or halide
contamination in the final material. Here we report
on the extension of this strategy towards the synthesis of
[
Bi(OSiR ) ] (1, R ϭ Me; 2, R ϭ Et; 3, R ϭ iPr) and describe
3 3
3
2
the molecular structures of compounds 1 and 3.
interest, because they readily eliminate R SiOSiR at moder-
3
3
ate temperatures to give the corresponding metal oxides or
metal oxosilanolates [5, 6Ϫ10]. It should be possible to con-
trol the thermal stability of main group metal silanolates as
well as their solubility by variation of the organic groups
attached to silicon in order to synthesize tailor-made metal
oxoclusters or metal oxide particles. We are currently follow-
ing this approach towards bismuth oxide-based materials [11,
Results and Discussion
Syntheses
The bismuth silanolates [Bi(OSiR ) ] (1, R ϭ Me; 2, R ϭ
Et; 3, R ϭ iPr) were prepared from [Bi(OtBu) ] and the
corresponding silanol in toluene (eq. (1)). Apparently, upon
addition of the silanol to the bismuth alkoxide suspension
some of the solid material was consumed, but we never ob-
served a clear solution. After filtration of the reaction mix-
ture all volatiles were evaporated to give solid [Bi(OSiMe ) ]
3
3
3
12], which are of interest for a variety of applications in areas
such as catalysis, sensing and electronics [13]. Among the
bismuth tris(triorganosilanolates), bismuth tris(trimethylsil-
3
3
(
1), liquid [Bi(OSiEt ) ] (2) and oily [Bi(OSiiPr ) ] (3),
3 3 3 3
which solidified upon cooling to 4 °C.
*
Dr. M. Mehring
Anorganische Chemie II,
Fachbereich Chemie der Universität Dortmund
Otto-Hahn-Str. 6
D-44221 Dortmund (Germany)
Fax: ϩ49 (0) 231 755-5048
E-mail: michael.mehring@uni-dortmund.de
Z. Anorg. Allg. Chem. 2005, 631, 2433Ϫ2438
DOI: 10.1002/zaac.200500264
 2005 WILEY-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim
2433

S. Paalasmaa, D. Mansfeld, M. Schürmann, M. Mehring
The moisture sensitive compounds 1؊3 are soluble in com-
80-0627), with some Bi (SiO ) (JCPDS No. 76-1726). No-
4
4 3
mon organic solvents such as toluene, THF, Et O and
tably, the thermally induced decomposition of [Bi(OSi-
2
CH Cl . In contrast to [Bi(OSiMe tBu) ] [11] attempts at
Me tBu) ] results in the exclusive formation of Bi SiO
2
2
2
3
2
3
12
20
purifying the bismuth silanolates 1؊3 by Kugelrohr-distil-
lation in high-vacuum (10 mbar, temperature range
[11]. Compounds 2 and 3 exhibit higher thermal stability
compared with 1 which was already recognized during our
attempts to distillate the bismuth silanolates. However, ther-
mogravimetric analyses of liquid [Bi(OSiEt ) ] (2) were not
Ϫ3
1
20Ϫ180 °C) failed. Instead, we obtained dark brown resi-
dues and colorless distillates indicating partial decompo-
3
3
sition. In case of the ethyl- and i-propyl derivatives 2 and
reproducible. The DTA-TG analysis of [Bi(OSiiPr ) ] (3)
3 3
3
, respectively, the distillates were composed of the bismuth
shows two steps in the temperature ranges 150Ϫ180 °C and
180Ϫ350 °C. The total weight loss of 77 % indicates that
partial evaporation of a bismuth-containing compound,
most likely the bismuth silanolate 3, takes place. The yellow
residue consists mainly of Bi12SiO20 (JCPDS No. 80-0627),
silanolates and the corresponding silanols, whereas in case
of the methyl derivative 1 Me SiOSiMe was exclusively ob-
tained.
Interestingly, it was reported previously that salt-elimin-
ation starting from SnCl and NaOSiMe as well as the
3
3
but some Bi (SiO ) (JCPDS No. 76-1726) and Ͱ-Bi O
2
3
4 4 3 2 3
reaction of [Sn(OMe) ] with Me SiOH gave [Sn O(OSi-
(JCPDS No. 71-2274) are also formed, as indicated by pow-
der XRD.
2
3
2
Me ) ] and Me SiOSiMe instead of [Sn(OSiMe ) ] [8].
3
2 n
3
3
3 2 2
However, the latter compound is accessible in high yield
either by the reaction of di(cyclopentadienyl)tin with Me3-
SiOH or by reaction of [Sn{N(SiMe ) } ] with carbon diox-
Molecular structures
3
2 2
ide [8, 15]. Heating of pure [Sn(OSiMe ) ] at 180 °C results
3
2
Single crystals of [Bi(OSiMe ) ] (1) suitable for X-ray dif-
fraction analysis were grown from a highly concentrated
3
3
in a clean conversion to [Sn O (OSiMe ) ] [10]. In case of
6
4
3 4
the corresponding lead compound [Pb(OSiMe ) ], reports
3
2
toluene solution at 4 °C. Compound 1 crystallizes in the
on its chemical properties and thermal stability are ambigu-
ous [5, 7, 9, 16] and its molecular structure is still unknown.
However, the formation of the lead oxosilanolate
¯
space group P1 with three crystallographically independent
molecules in the unit cell. These molecules are associated by
weak intermolecular bismuthϪoxygen interactions to give a
trimer in the solid state (Fig. 1). In solution only one type
[
[
[
Pb O (OSiMe ) ] was observed upon heating to 80 °C of
7
2
3 10
Pb{N(SiMe ) } ] in presence of tBuNCO. Most likely
1
3
2 2
of Me Si groups is detected by variable temperature H
3
Pb(OSiMe ) ] is formed as the initial product, which de-
1
3
2
NMR spectra. A minor shift of the H NMR signal was
composes to give the lead oxosilanolate [9]. We assume that
such condensation reactions also take place upon heating of
observed upon lowering the temperature, but even at
Ϫ60 °C the linewidth did not change significantly. We also
obtained single crystals of [Bi(OSiiPr ) ] (3) from the neat
[
Bi(OSiMe ) ] (1), as was indicated by the following NMR
3 3
3
3
experiments. Heating a toluene-d solution of 1 in a sealed
8
compound at 4 °C (Fig. 3), but in contrast to 1 compound
NMR tube at 90 °C for 1 h resulted in a cloudy solution
3
3
is monomeric in the solid state. The bismuth silanolate
, which shows extensive disorder of the organic groups,
1
(
sample A). The H NMR spectrum showed two signals
at 0.15 ppm and 0.30 ppm assigned to Me SiOSiMe and
3
3
crystallizes in the space group Pbcm. Crystallographic data
of both compounds are listed in Table 1. Selected bond
angles and distances of compound 1 are given in Table 2
whereas those of 3 are listed in the caption of Figure 3.
The most striking feature of the molecular structure of 1
is the formation of a loosely associated trimer with the bis-
muth atoms in two different coordination environments.
The coordination geometry at the bismuth atoms Bi(1) and
Bi(3) is best described as 3ϩ2 coordination whereas Bi(2)
shows a 3ϩ3 coordination (Fig. 2).
BiϪOSiMe groups, respectively. The latter might be as-
3
signed to the starting material 1 and/or bismuth oxosilanol-
ates, which show fast exchange of their silanolate groups.
2
9
This assumption is further supported by Si NMR which
showed only one signal at 7.3 ppm being assigned to
Me SiOSiMe and by the observation that addition of a
3
3
small amount of Me SiOH to a toluene-d solution of
3
8
[
Bi(OSiMe ) ] (1) caused the 29Si NMR resonance of the
3 3
latter to disappear. Heating sample A for 12 h at 90 °C
results in the precipitation of a colorless solid. The NMR
Short intramolecular BiϪO bonds with distances in the
1
sample shows exclusively the H NMR resonance of
˚
range 2.041(3)Ϫ2.119(3) A and secondary intermolecular
Me SiOSiMe . Attempts to isolate a pure bismuth oxo-
BiϪO
bonds
with
distances
in
the
range
3
3
silanolate upon thermal treatment of the trimethylsilanolate
failed so far, but we have isolated several bismuth oxo
2.686(6)Ϫ3.227(3) A˚ are observed for the trimethyl-deriva-
tive 1. In comparison with the monomeric bismuth silanol-
1
˚
ates [Bi(OSiMe tBu) ] (BiϪO 2.003(14)Ϫ2.05(2) A) [11]
2 3
and [Bi(OSiiPr ) ] (3) (BiϪO 1.998(2)Ϫ2.065(5) A), the pri-
silanolates as a result of partial hydrolysis [11, 17].
˚
The DTA-TG analysis of [Bi(OSiMe ) ] (1) indicates that
3
3
3 3
decomposition starts immediately after melting at approxi-
mately 80 °C. The weight loss observed is close to the calcu-
lated value for the formation of Bi O and complete release
mary BiϪO bonds are only slightly elongated as a result of
the additional bismuthϪoxygen interactions. Interestingly,
2
3
the corresponding antimony compound [Sb(OSiMe ) ] is a
3 3 2
of Me SiOSiMe (obs. 51.1 %; calcd. 50.7 %). However, the
dimer in the solid state with three short SbϪO distances of
1.906(3)Ϫ1.954(2) A and a longer one of 2.897(2) A [18].
Its coordination environment was described as trigonal bi-
3
3
˚
˚
powder XRD pattern of the yellow residue is indicative for
the formation of a major product Bi SiO (JCPDS No.
1
2
20
2434
 2005 WILEY-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim
zaac.wiley-vch.de
Z. Anorg. Allg. Chem. 2005, 631, 2433Ϫ2438

Three Homoleptic Bismuth Silanolates
Figure 2 Compound 1: View of the bismuthϪoxygen polyhedra ob-
˚
served for Bi(1) and Bi(2) including bond distances given in A. The
5
BiO -polyhedron associated with Bi(3) is similar to that of Bi(1).
9
6.9(5)Ϫ97.9(7)°) [11] are significantly larger and correlate
with an increasing steric bulk of the R Si-moieties. Thus,
3
steric effects seem to have a greater influence on the
OϪBiϪO bond angles than weak BiϪO interactions as ob-
served in compound 1. The coordination geometry at the
bismuth atoms in the trimethylsilanolate-derivative 1 is best
described as a trigonal pyramid with three oxygen atoms
and a stereochemically active lone pair occupying the cor-
ners. Additional oxygen atoms associated with the silanol-
ate groups of neighboring molecules complete the coordi-
nation environment, but do not significantly influence the
coordination polyhedron at the bismuth atom in its first
coordination shell (Fig. 2). A similar bonding situation was
reported for [Bi(OSiPh ) (THF) ] which shows short coval-
3 3
Figure 1 Molecular structure of [Bi(OSiMe ) ] (1) indicating the
atom numbering scheme; H atoms are omitted for clarity. A trimer
results from weak intermolecular BiϪO interactions.
3
3
3
˚
pyramidal with the lone pair occupying an equatorial posi-
tion. In compound 1 the OϪBiϪO bond angles associated
with the primary bonds are in the range
ent BiϪO bonds of 2.04(1) A, long BiϪO secondary bonds
˚
of 2.95(1) A to the THF ligands and OϪBiϪO angles of
93.0(5)° associated with the primary bonds [19].
The central structural unit of the trimer 1 is based on
8
3.60(11)Ϫ95.40(15)° with an average value of 91.9°. The
OϪBiϪO bond angles in the monomeric bismuth silanolate
the [M (µ -OR) (µ-OR) ] fragment (A), which is a common
3 3 2 3
[
Bi(OSiiPr ) ] (3) (see Figure 3) with an average value of
3 3
9
3.1° (OϪBiϪO 84.61(13)Ϫ101.81(13)°) and those of
˚
Table 2 Selected bond lengths/A and angles/deg for [Bi(OSiMe
(1).
3 3
) ]
[
Bi(OSiMe tBu) ] with an average value of 97.3° (OϪBiϪO
2
3
Bi(1)ϪO(1)
Bi(1)ϪO(4)
Bi(1)ϪO(6)
Bi(1)ϪO(7)
Bi(1)ϪO(9)
Bi(2)ϪO(1)
Bi(2)ϪO(3)
Bi(2)ϪO(4)
O(1)ϪBi(1)ϪO(4)
O(1)ϪBi(1)ϪO(9)
O(1)ϪBi(1)ϪO(7)
O(1)ϪBi(1)ϪO(6)
O(4)ϪBi(1)ϪO(6)
O(4)ϪBi(1)ϪO(7)
O(4)ϪBi(1)ϪO(9)
O(6)ϪBi(1)ϪO(7)
O(6)ϪBi(1)ϪO(9)
O(7)ϪBi(1)ϪO(9)
O(1)ϪBi(2)ϪO(3)
O(1)ϪBi(2)ϪO(4)
O(1)ϪBi(2)ϪO(5)
O(1)ϪBi(2)ϪO(7)
O(1)ϪBi(2)ϪO(8)
O(3)ϪBi(2)ϪO(4)
O(3)ϪBi(2)ϪO(5)
O(3)ϪBi(2)ϪO(7)
2.826(3)
2.078(3)
2.877(3)
2.092(3)
2.073(3)
2.908(3)
2.041(3)
3.230(3)
Bi(2)ϪO(5)
Bi(2)ϪO(7)
Bi(2)ϪO(8)
Bi(3)ϪO(1)
Bi(3)ϪO(2)
Bi(3)ϪO(5)
Bi(3)ϪO(6)
Bi(3)ϪO(7)
O(3)ϪBi(2)ϪO(8)
O(4)ϪBi(2)ϪO(5)
O(4)ϪBi(2)ϪO(7)
O(4)ϪBi(2)ϪO(8)
O(5)ϪBi(2)ϪO(7)
O(5)ϪBi(2)ϪO(8)
O(7)ϪBi(2)ϪO(8)
O(1)ϪBi(3)ϪO(2)
O(1)ϪBi(3)ϪO(5)
O(1)ϪBi(3)ϪO(6)
O(1)ϪBi(3)ϪO(7)
O(2)ϪBi(3)ϪO(5)
O(2)ϪBi(3)ϪO(6)
O(2)ϪBi(3)ϪO(7)
O(5)ϪBi(3)ϪO(6)
O(5)ϪBi(3)ϪO(7)
O(6)ϪBi(3)ϪO(7)
2.100(3)
Table 1 Crystallographic data for [Bi(OSiMe
3 3
) ] (1) and [Bi(OSi-
3.227(3)
2.050(3)
2.100(2)
2.063(3)
2.686(3)
2.119(3)
2.706(3)
95.40(15)
126.53(9)
53.09(7)
iPr ] (3).
3 3
)
Empirical formula
Formula weight
Crystal system
Space group
C
27
H
81Bi
3
O
9
Si
9
C
27
H63BiO
3
Si
3
1429.67
triclinic
P1
a ϭ 10.323(1)
b ϭ 13.805(1)
c ϭ 21.096(1)
Ͱ ϭ 91.871(4)
β ϭ 94.639(3)
729.02
orthorhombic
Pbcm
a ϭ 7.201(1)
b ϭ 23.367(5)
c ϭ 20.893(4)
¯
˚
Cell constants/A and °
87.60(9)
162.03(10)
69.07(9)
59.10(8)
117.19(11)
76.57(9)
144.69(10)
87.58(11)
94.79(12)
70.64(10)
113.33(10)
93.20(11)
99.04(11)
67.87(7)
69.14(9)
55.13(7)
157.37(12)
123.99(12)
92.72(12)
154.05(11)
γ ϭ 110.802(3)
2795.3(3)
2
1.699
9.648
92.95(12)
108.53(12)
91.00(11)
74.00(10)
83.60(11)
71.55(9)
105.91(11)
95.45(12)
160.28(10)
149.00(10)
78.63(8)
Volume/A3
Z
d
˚
3515.6(12)
4
1.377
5.140
0.20 x 0.10 x 0.10
2.96 to 27.47
56808
calcd/g·cmϪ3
Absorption coefficient/mm
Crystal size/mm
Ϫ1
0.19 x 0.12 x 0.10
Theta range for data collection/° 2.91 to 27.48
No. of reflections collected
No. of unique reflections
R indices
37114
12782 [Rint ϭ 0.039] 4142 [Rint ϭ 0.059]
R1 ϭ 0.0249
R1 ϭ 0.0205
[
I > 2sigma(I)]
R indices (all data)
Largest diff. peak and hole (e·A ) 0.879 / Ϫ0.874
wR2 ϭ 0.0567
Ϫ3
wR2 ϭ 0.0300
0.871 / Ϫ1.024
74.04(10)
˚
Z. Anorg. Allg. Chem. 2005, 631, 2433Ϫ2438
zaac.wiley-vch.de
 2005 WILEY-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim
2435

S. Paalasmaa, D. Mansfeld, M. Schürmann, M. Mehring
Conclusion
Our previous attempts to prepare bismuth silanolates using
metathesis routes often led to incorporation of alkali metals
into the final product [14]. Here we have shown that bis-
muth silanolates such as [Bi(OSiR ) ] (1, R ϭ Me; 2, R ϭ
3
3
Et; 3, R ϭ iPr) alternatively can be prepared in high yield
starting from the readily available [Bi(OtBu) ] and the cor-
3
responding silanol. For both structurally characterized
compounds 1 and 3 the lone pair at the bismuth atom is
suggested to be stereochemically active. In contrast to bis-
muth alkoxides the tendency for aggregation in solution as
well as in the solid state can be almost neglected for bis-
muth silanolates 1-3, which makes them highly soluble in
common organic solvents. With respect to the synthesis of
thin bismuth oxide or bismuth silicate films the thermal sta-
bility of the bismuth silanolates seems to be insufficient for
their use in a conventional MOCVD process, but their high
solubility makes the bismuth silanolates potential precur-
sors for applications based on the sol-gel process or liquid
injection MOCVD.
3 3
Figure 3 Molecular structure of [Bi(OSiiPr ) ] (3) indicating the
atom numbering scheme; H atoms are omitted for clarity. Selected
structural parameters:
˚
˚
˚
Bi(1)ϪO(1) 1.998(2) A, Bi(1)ϪO(2) 2.065(5) A, Bi(1)ϪO(3) 2.005(5) A;
O(1)ϪBi(1)ϪO(2)
O(2)ϪBi(1)ϪO(3) 92.79(13)°.
84.61(13)°,
O(1)ϪBi(1)ϪO(3)
101.81(13)°,
Experimental Section
motif observed in a large number of homo- and heteromet-
General procedures and instrumentation
allic metal alkoxides such as [Pr(OCMe CF3)3]3 [20],
2
All manipulations were performed under exclusion of oxygen and
moisture using the Schlenk type technique and argon atmosphere.
Solvents were distilled from appropriate drying agents prior to use.
[Bi(OtBu) ] [28] and Me SiOH [29] were prepared according to lit-
[
Ln (OtBu) (THF) ] (Ln ϭ La, Nd) [21], [M (OtBu) -
3 9 2 3 9
(
HOtBu) ] (M ϭ Y, La) [22], [Ba Zr(OtBu) (THF) ] [23],
2 2 8 2
[
[
NaTh (OtBu) ] [24], [Sr Ti(OiPr) (HOiPr) ] [25] and
2 9 2 8 3
3
3
Ti Tl(OEt) (OCH tBu) ] [26]. However, such a pro-
3 3
erature procedures. Et SiOH (ABCR) and iPr SiOH (ABCR) were
2
3
2
6
nounced difference for the bridging metalϪoxygen dis-
tances is unusual for homometallic alkoxides and might be
interpreted as a result of the stereochemical activity of the
lone pair at the bismuth atom and is indicative for a low
Lewis-acidity.
used as received. Elemental analyses were performed on an instru-
ment from Carlo Erba Strumentzione (model 1106). No satisfactory
elemental analysis was obtained for 1 as a result of its moisture
sensitivity. Thermal analyses were recorded using a thermoanalyzer
TA1 from Mettler Instrumente AG. The DTA-TG measurements
Ϫ1
were performed at a heating rate of 6 °C min to a maximum
temperature of 700 °C in an atmosphere of flowing argon using
Al O as reference material. The residues were examined by powder
2 3
x-ray diffraction using a Phillips PW1050/25 diffractometer. NMR
spectra were recorded on Bruker AC 200 and Bruker DRX 400
spectrometer. Chemical shifts δ are given in ppm and were refer-
4
enced against Me Si. The IR spectra were run as Nujol mulls and
absorption bands assigned to the compounds in the range
Ϫ1
4
00Ϫ1400 cm are listed.
Synthesis ؊ General procedure
Compounds 1؊3 were prepared according to the same procedure:
A solution of the triorganosilanol in approximately 50 ml toluene
The above-mentioned examples of metal alkoxides with a
core structure of type A nicely demonstrate that coordi-
nation of additional alcohol molecules is very common and
was also reported for bismuth alkoxides [27], but it is rarely
observed in metal silanolates. Besides the lone pair at the
bismuth atom being stereochemically active, this might be
another reason for the formation of the unprecedented
molecular structure of 1 showing a hexacoordinate (3ϩ3
coordination) and two pentacoordinate (3ϩ2 coordination)
bismuth atoms within a weakly bonded aggregate.
3
is slowly added to a cloudy solution of [Bi(OtBu) ] in approxi-
mately 70 ml toluene and the solution is stirred at room tempera-
ture overnight. The quantities used were: 10.8 g (25.3 mmol) [Bi(-
OtBu)
OtBu)
OtBu)
3
3
3
] and 6.8 g (75.9 mmol) Me
] and 8.3 g (62.8 mmol) Et
] and 5.0 g (28.7 mmol) iPr
3
SiOH; 9.0 g (21.0 mmol) [Bi(-
SiOH; 4.1 g (9.6 mmol) [Bi(-
SiOH. All volatiles were
3
3
removed in vacuo at 40 °C. The residue was dissolved in pentane
and solid material was filtered off. The solvent was removed in
vacuo and the residue dried at 40 °C to give solid [Bi(OSiMe
3 3
) ]
(1), liquid [Bi(OSiEt ) ] (2) and oily [Bi(OSiiPr ) ] (3). The latter
3
3
3 3
solidified upon cooling to 4 °C.
2436
 2005 WILEY-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim
zaac.wiley-vch.de Z. Anorg. Allg. Chem. 2005, 631, 2433Ϫ2438

Three Homoleptic Bismuth Silanolates
Synthesis of [Bi(OSiMe ) ] (1)
Road, Cambridge, CB2 1EZ, UK (Fax: ϩ44 1223 336033; e-mail:
deposit@ccdc.cam.ac.uk).
3
3
9 3 3
Yield: 10.6 g (88 %), m.p. 77 °C. Anal. Calcd. for C H27BiO Si
Acknowledgement. We acknowledge the Deutsche Forschungsgeme-
inschaft, the Fonds der Chemischen Industrie, the Fachbereich
Chemie der Universität Dortmund and Professor Dr. K. Jurkschat
for support of this work. S. P. is grateful to the department of
chemistry at the University of Joensuu (Finnland) and the foun-
dation of Heikki and Hilma Honkanen for financial support as
well as for receipt of an ERASMUS-grant.
(476.6): C, 22.7; H, 5.7. Found: C, 20.0; H, 5.2 %.
1
H NMR (400.13 MHz, toluene-d
8
, 23 °C) δ ϭ 0.30 (s, FWHM 5.8 Hz,
); H NMR (400.13 MHz, toluene-d , Ϫ60 °C) δ ϭ 0.37 (s, FWHM
); C{ H} NMR (100.63 MHz, toluene-d ) δ ϭ 4.4 (JCϪSi
) δ ϭ 11.1. IR (Nujol) ν˜ /
1
CH
5
3
8
1
3
1
.2 Hz, CH
6 Hz) (SiCH
3
8
ϭ
9
1
5
3
). 2 Si{ H} NMR (79.49 MHz, C
D
6 6
Ϫ1
cm ϭ 1301w, 1259sh, 1247s, 1177w, 1056w, 934s, 896s, 866s, 839s, 746m,
30sh, 679w, 622w, 538w (b), 499sh, 449w.
7
Synthesis of [Bi(OSiEt ) ] (2)
3
3
References
3 3
Yield: 12.0 g (95 %). Anal. Calcd. for C18H45BiO Si (602.8): C,
[
1] A good overview is provided by the recent review articles: (a)
S. Mathur, H. Shen, in Encyclopedia of Nanoscience and Nano-
technology, Vol. 4 (Ed.: H. S. Nalwa), American Scientific Pub-
lishers, 2004, 131Ϫ191; (b) M. Veith, J. Chem. Soc., Dalton
Trans. 2002, 2405Ϫ2412; (c) A. Singh, R. C. Mehrotra, Coord.
Chem. Rev. 2004, 248, 101Ϫ118; (d) L. G. Hubert-Pfalzgraf,
J. Mater. Chem. 2004, 14, 3113Ϫ3123; (e) U. Schubert, in
Comprehensive Coordination Chemistry II (Eds.: J. A. McLev-
erty, T. J. Meyer), Elsevier Ltd., Oxford, 2004, 629Ϫ656; (f) J.
A. Crayston, in Comprehensive Coordination Chemistry II
35.9; H, 7.5. Found: C, 36.2; H, 8.0 %.
1
H NMR (400.13 MHz, C
6
D
6
) δ ϭ 0.65 (quart, 18 H, CH
); C{ H} NMR (100.63 MHz, C ) δ ϭ 7.5 (CH ), 8.4 (CH
6 6
6 Hz). Si{ H} NMR (79.49 MHz, C D
) δ ϭ 14.1. IR (Nujol) ν˜ /cm
2
), 1.07 (t, 27 H,
13
1
CH
3
6
D
6
3
2
, JCϪSi
ϭ
ϭ
29
1
Ϫ1
5
1
6
414m, 1261sh, 1238m, 1015m, 972w, 922m, 875s, 848sh, 737s, 720sh, 696w,
78w, 651w, 581w, 558w, 520w, 455w.
Synthesis of [Bi(OSi-iPr ) ] (3)
3
3
3 3
Yield: 5.5 g (79 %), m.p. 35 °C. Anal. Calcd. for C27H63BiO Si
(
2
Eds.: J. A. McLeverty, T. J. Meyer), Elsevier Ltd., Oxford,
004, 711Ϫ730; (g) R. C. Mehrotra, A. Singh, Prog. Inorg.
Chem. 1997, 46, 239Ϫ454.
[2] Selcted references: (a) H. Schmidbaur, Angew. Chem. 1965, 77,
06Ϫ216; Angew. Chem., Int. Ed. Engl. 1965, 4, 201Ϫ211; (b)
F. Schindler, H. Schmidbaur, Angew. Chem. 1967, 79,
97Ϫ708, Angew. Chem., Int. Ed. Engl. 1967, 6, 683Ϫ694; (c)
F. Schindler, H. Schmidbaur, U. Krüger, Angew. Chem. 1965,
7, 865, Angew. Chem., Int. Ed. Engl. 1965, 4, 876; (d) S. N.
(729.0): C, 44.5; H, 8.7. Found: C, 44.1; H, 8.7 %.
1
H NMR (200.13 MHz, C
6
D
6
) δ ϭ 1.11 (sept., 9 H, CH), 1.19 (d, 54 H,
); C{ H} NMR (50.31 MHz, C ) δ ϭ 14.6 (CH), 18.7 (CH ).
) δ ϭ 11.4. IR (Nujol) ν˜ /cm ϭ 1366m,
13
1
CH
3
6
D
6
3
29
1
Ϫ1
6 6
Si{ H} NMR (59.62 MHz, C D
2
1
5
252m, 1160w, 1072w, 992w, 950w, 915w, 872m (b), 800w, 677m, 660sh,
91w, 572w, 520w, 459w.
6
7
Structure determination
Borisov, M. G. Voronkov, E. Y. Lukevits, Organosilicon Heter-
opolymers and Hetero Compounds, Plenum, New York, 1970;
(e) H. Schmidbaur, J. Adlkofer, A. Shiotani, Chem. Ber. 1972,
105, 3389Ϫ3396; (f) M. Veith, C. Mathur, V. Huch, J. Chem.
Soc., Dalton Trans. 1997, 995Ϫ999; (g) P. S. Coan, J. C. Huff-
man, K. G. Caulton, Inorg. Chem. 1992, 31, 4207Ϫ4209; (h)
T. Greiser, O. Jarchow, K. H. Klaska, E. Weiss, Chem. Ber.
1978, 111, 3360Ϫ3366.
Intensity data for the colorless crystals were collected on a Nonius
KappaCCD diffractometer with graphite-monochromated Mo Kα
radiation at 143 K (1) and 173 K (3). The data collection covered
almost the whole sphere of reciprocal space with 4 sets (1) and 5
sets (3) at different κ-angles and 421 frames (1) and 512 frames (3)
via ω-rotation (∆/ω ϭ 1°) at two times 70 s (1) and 75 s (3) per
frame. The crystalϪdetector distance was 3.4 cm. Crystal decay was
monitored by repeating the initial frames at the end of data collec-
tion. Analyzing the duplicate reflections there was no indication
for any decay. The structures were solved by direct methods
SHELXS97 [30] and successive difference Fourier syntheses. Re-
finement applied full-matrix least-squares methods SHELXL97
[3] For recent review articles see: (a) J. Beckmann, K. Jurkschat,
Coord. Chem. Rev. 2001, 215, 267Ϫ300; (b) R. Murugavel, A.
Voigt, M. G. Walawalkar, H. W. Roesky, Chem. Rev. 1996, 96,
2205Ϫ2236; (c) F. J. Feher, T. A. Budzichowski, Polyhedron
1995, 14, 3239Ϫ3253; (d) R. Murugavel, V. Chandrasekhar, H.
W. Roesky, Acc. Chem. Res. 1996, 29, 183Ϫ189; (e) L. King,
A. C. Sullivan, Coord. Chem. Rev. 1999, 189, 19Ϫ57; (f) V.
Lorenz, A. Fischer, S. Giessmann, J. W. Gilje, Y. Gun’ko, K.
Jacob, F. T. Edelmann, Coord. Chem. Rev. 2000, 206,
321Ϫ368.
[4] (a) J. Jarupatrakorn, M. P. Coles, T. D. Tilley, Chem. Mater.
2005, 17, 1818Ϫ1828; (b) K. L. Fujdala, T. D. Tilley, Chem.
Mater. 2002, 14, 1376Ϫ1384; (c) C. G. Lugmair, K. L. Fujdala,
T. D. Tilley, Chem. Mater. 2002, 14, 888Ϫ898; (d) K. L.
Fujdala, T. D. Tilley, Chem. Mater. 2001, 13, 1817Ϫ1827; (e)
R. Rulkens, J. L. Male, K. W. Terry, B. Olthof, A. Khodakov,
A. T. Bell, E. Iglesia, T. D. Tilley, Chem. Mater. 1999, 11,
2966Ϫ2973; (f) K. W. Terry, K. Su, T. D. Tilley, A. L. Rheing-
old, Polyhedron 1998, 17, 891Ϫ897; (g) W. A. Wojtczak, M. J.
Hampden-Smith, E. N. Duesler, Inorg. Chem. 1996, 35,
6638Ϫ6639; (h) J. Hambrock, S. Rabe, K. Merz, A. Birkner,
A. Wohlfart, R. A. Fischer, M. Driess, J. Mater. Chem. 2003,
13, 1731Ϫ1736; (i) M. J. McGeary, R. C. Wedlich, P. S. Coan,
[31]. The H atoms were placed in geometrically calculated positions
using a riding model with Uiso constrained at 1.2 times Ueq of the
carrier C atom for non-methyl and 1.5 times Ueq of the carrier C
atom for methyl groups. Atomic scattering factors for neutral
atoms and real and imaginary dispersion terms were taken from
International Tables for X-ray Crystallography. Absorption correc-
tion was carried out with multi-scan using SCALEPACK [32]
(1, Tmin ϭ 0.262, Tmax ϭ 0.445; 3, Tmin ϭ 0.426, Tmax ϭ 0.627).
One methyl group in 1 is disordered over two positions with occu-
pancies of 0.4 (C(91B) and 0.6 (C(91A). All atoms in 3 except Bi(1)
and O(1) occupy two symmetry related positions and were refined
with an occupancy of 0.5. Bi(1) and O(1) occupy a special position.
Attempts to refine disorder at O(1) failed. The figures were created
by SHELXTL [33]. Crystallographic data for the structures re-
ported in this paper have been deposited with the Cambridge Crys-
tallographic Data Centre as supplementary material publication no.
CCDC-272445 (1) and CCDC-272444 (3). Copies of the data can
be obtained free of charge on application to CCDC, 12 Union
Z. Anorg. Allg. Chem. 2005, 631, 2433Ϫ2438
zaac.wiley-vch.de
 2005 WILEY-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim
2437

S. Paalasmaa, D. Mansfeld, M. Schürmann, M. Mehring
K. Folting, K. G. Caulton, Polyhedron 1992, 11, 2459Ϫ2473;
j) A. Roy, S. Polarz, S. Rabe, B. Rellinghaus, H. Zahres, F. E.
[16] W. Patnode, F. C. Schmidt, J. Am. Chem. Soc. 1945, 67,
2272Ϫ2273.
(
Kruis, M. Driess, Chem. Eur. J. 2004, 10, 1565Ϫ1575.
5] H. Schmidbaur, M. Bergfeld, Z. Anorg. Allg. Chem. 1968,
[17] Manuscript in preparation; parts of the results were presented
at the Chemiedozententagung 2005, 6.Ϫ9.03.2005, Munich,
Germany, abstract B38.
[
363, 84Ϫ88.
[
6] (a) H. Schmidbaur, M. Bergfeld, F. Schindler, Z. Anorg. Allg.
Chem. 1968, 363, 73Ϫ83; (b) M. J. McGeary, R. H. Cayton,
K. Folting, J. C. Huffman, K. G. Caulton, Polyhedron 1992,
[18] M. Baier, K. Angermaier, H. Schmidbaur, Z. Naturforsch.
1994, 49b, 855Ϫ858.
[
[
[
19] M.-C. Massiani, R. Papiernik, L. G. Hubert-Pfalzgraf, J.-C.
Daran, Polyhedron 1991, 10, 437Ϫ445.
20] D. C. Bradley, H. Chudzynska, M. B. Hursthouse, M. Motev-
alli, R. W. Wu, Polyhedron 1993, 12, 2955Ϫ2960.
21] (a) W. J. Evans, M. S. Sollberger, T. P. Hanusa, J. Am. Chem.
Soc. 1988, 110, 1841Ϫ1850; (b) J. Gromada, A. Mortreux, T.
Chenal, J. W. Ziller, F. Leising, J. F. Carpentier, Chem. Eur. J.
11, 1369Ϫ1382; (b) C. Gaffney, P. G. Harrison, T. J. King, J.
Chem. Soc., Chem. Comm. 1980, 1251Ϫ1252.
[
[
[
7] W.-W. Du Mont, M. Grenz, Chem. Ber.-Recl. 1981, 36,
1
180Ϫ1181.
8] W.-W. Du Mont, M. Grenz, Z. Naturforsch. 1983, 38b,
13Ϫ114.
1
2002, 8, 3773Ϫ3788.
9] C. S. Weinert, I. A. Guzei, A. L. Rheingold, L. R. Sita, Or-
ganometallics 1998, 17, 498Ϫ500.
[
22] (a) M. Veith, S. Mathur, A. Kareiva, M. Jilavi, M. Zimmer, V.
Huch, J. Mater. Chem. 1999, 9, 3069Ϫ3079; (b) D. C. Bradley,
H. Chudzynska, M. B. Hursthouse, M. Motevalli, Polyhedron
[
[
10] L. R. Sita, R. Xi, G. P. A. Yap, L. M. Liable-Sands, A. L.
Rheingold, J. Am. Chem. Soc. 1997, 119, 756Ϫ760.
11] D. Mansfeld, M. Mehring, M. Schürmann, Angew. Chem.
1
991, 10, 1049Ϫ1059.
23] M. Veith, S. Mathur, V. Huch, T. Decker, Eur. J. Inorg. Chem.
998, 1327Ϫ1332.
[
2005, 116, 250Ϫ254, Angew. Chem., Int. Ed. Engl. 2005, 44,
1
245Ϫ249.
[
[
24] D. L. Clark, J. G. Watkin, Inorg. Chem. 1993, 32, 1766Ϫ1772.
25] I. Baxter, S. R. Drake, M. B. Hursthouse, K. M. A. Malik, D.
M. P. Mingos, J. C. Plakatouras, D. J. Otway, Polyhedron 1998,
[
[
12] D. Mansfeld, M. Mehring, M. Schürmann, Z. Anorg. Allg.
Chem. 2004, 630, 1795Ϫ1797.
13] Selected references: (a) K. H. Whitmire, Chemtracts Ϫ Inorg.
Chem. 1995, 7, 167Ϫ181; (b) J. H. Thurston, T. O. Ely, D.
Trahan, K. H. Whitmire, Chem. Mater. 2003, 15, 4407Ϫ4416;
17, 625Ϫ639.
[
[
26] T. J. Boyle, C. A. Zechmann, T. M. Alam, M. A. Rodriguez,
C. A. Hijar, B. L. Scott, Inorg. Chem. 2002, 41, 946Ϫ957.
27] (a) T. J. Boyle, D. M. Pedrotty, B. Scott, J. W. Ziller, Polyhedron
(
c) C. Limberg, M. Hunger, W. Habicht, E. Kaifer, Inorg.
Chem. 2002, 41, 3359Ϫ3365; (d) A. Cabot, A. Marsal, J. Ar-
biol, J. R. Morante, Sensor Actuat. B Chem. 2004, 99, 74Ϫ89;
1998, 17, 1959Ϫ1974; (b) V. G. Kessler, N. Y. Tiurova, E. P.
Turevskaya, Inorg. Chem. Commun. 2002, 5, 549Ϫ551.
28] W. J. Evans, J. J. H. Hain, J. W. Ziller, J. Chem. Soc., Chem.
Commun. 1989, 1628Ϫ1629.
(e) B. H. Park, B. S. Kang, S. D. Bu, T. W. Noh, J. Lee, W. Jo,
[
[
Nature 1999, 401, 682Ϫ684; (f) C. A. Paz de Araujo, J. D.
Cuchiaro, L. D. McMillan, M. C. Scott, J. F. Scott, Nature
29] L. H. Sommer, E. W. Pietrusza, F. C. Whitmore, J. Am. Chem.
1995, 374, 627Ϫ629; (g) R. K. Grasselli, J. D. Burrington, Adv.
Soc. 1946, 68, 2282Ϫ2284.
Catal. 1981, 30, 133Ϫ163; (h) P. Lee, Y. Gao, H. S. Sheu, V.
Petricek, R. Restori, Science 1989, 244, 62Ϫ63.
[
[
30] G. M. Sheldrick, Acta Crystallogr. 1990, A46, 467Ϫ473.
31] G. M. Sheldrick, University of Göttingen 1997.
[
[
14] M. Mehring, D. Mansfeld, M. Schürmann, in Organosilicon
Chemistry VI Ϫ From Molecule to Material (Eds.: N. Auner,
J. Weis), Wiley-VCH, in press.
[32] Z. Otwinowski, W. Minor, in Macromolecular Crystallography,
Part A, Vol. 276 (Eds.: C. W. Carter Jr, R. M. Sweet), Aca-
demic Press, New York, 1997, 307Ϫ326.
15] L. R. Sita, J. R. Babcock, R. Xi, J. Am. Chem. Soc. 1996,
[33] G. M. Sheldrick, Release 5.1 Reference Manual, Bruker AXS,
118, 10912Ϫ10913.
Inc., Madison, Wisconsin, USA 1997.
2438
 2005 WILEY-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim
zaac.wiley-vch.de
Z. Anorg. Allg. Chem. 2005, 631, 2433Ϫ2438