Neutral pentacoordinate silicon(IV) complexes with silicon-chalcogen (S, Se, Te) bonds

Article abstract of DOI:10.1002/chem.200900592

The neutral pentacoordinate silicon(IV) complexes 1 (SiS₂ONC skeleton), 2 (SiSeSONC), 3 (SiTeSONC), 6/9 (SiSe₂O₂C), 7 (SiSe₂S₂C), and 8/10 (SiSe4C) were synthesized and structurally characterized by u

Full text of DOI:10.1002/chem.200900592

FULL PAPER
DOI: 10.1002/chem.200900592
Neutral Pentacoordinate Silicon(IV) Complexes with Silicon–Chalcogen
(S, Se, Te) Bonds
Bastian Theis, Stefan Metz, Christian Burschka, Rꢀdiger Bertermann, Stefan Maisch, and
Reinhold Tacke*[a]
Dedicated to Professor Helmut Werner on the occasion of his 75th birthday
Abstract: The neutral pentacoordinate silicon(IV) complexes 1 (SiS2ONC skele-
ton), 2 (SiSeSONC), 3 (SiTeSONC), 6/9 (SiSe2O2C), 7 (SiSe2S2C), and 8/10
(SiSe4C) were synthesized and structurally characterized by using single-crystal X-
ray diffraction and multinuclear solid-state and solution-state (except for 6–9)
NMR spectroscopy. With the synthesis of compounds 1–3 and 6–10, it has been
demonstrated that pentacoordinate silicon compounds with soft chalcogen ligand
atoms (S, Se, Te) can be stable in the solid state and in solution.
Keywords: chalcogens · coordina-
tion chemistry · pentacoordination ·
silicon · tridentate ligands
Introduction
dination sphere. Most surprisingly, the oxygen analogue of 2
(Se/O exchange) and 3 (Te/O exchange), compound 4, could
not be synthesized. Although 4 contains a hard oxygen
ligand atom instead of the soft selenium (2) or tellurium
ligand atom (3), we were not able to prepare the pentacoor-
dinate silicon complex 4; instead, we obtained the isomeric
tetracoordinate silicon compound 5.
Small, strongly electronegative (hard) ligand atoms, such as
fluorine, oxygen, nitrogen, and carbon, are generally regard-
ed to be ideal candidates for pentacoordination of the hard
silicon(IV) coordination center.[1] However, pentacoordinate
silicon compounds with chloro or bromo ligands have also
been described in the literature (see for example, ref. [2]),
and recently, we have even succeeded in synthesizing a pen-
tacoordinate silicon(IV) complex that contains a soft iodo li-
gand.[2d] In addition, there are also a few reports on penta-
[3]
[2d,4]
ꢀ
ꢀ
coordinate silicon compounds with Si P or Si S bonds.
Obviously, contrary to the widely held view, the hard sili-
ACHTUNGTRENNUNGcon(IV) coordination center also tolerates soft ligand atoms.
We have now succeeded in synthesizing a further series of
novel pentacoordinate silicon(IV) complexes with soft
ꢀ
ꢀ
ligand atoms, compounds 1 (two Si S bonds), 2 (one Si S
ꢀ
ꢀ
ꢀ
and one Si Se bond), and 3 (one Si S and one Si Te bond),
showing that even soft selenium and tellurium ligand atoms
ꢀ
are tolerated. Pentacoordinate silicon compounds with Si
[5]
ꢀ
Se and Si Te bonds have not previously been reported.
Compounds 2 (SiSeSONC skeleton) and 3 (SiTeSONC skel-
eton) contain five different ligand atoms in the silicon coor-
In our search for novel Si coordination polyhedra with
soft ligand atoms, we have also succeeded in synthesizing
the zwitterionic l5Si-silicon(IV) complexes
6
and
9
[a] Dipl.-Chem. B. Theis, Dr. S. Metz, Dr. C. Burschka,
Dr. R. Bertermann, S. Maisch, Prof. Dr. R. Tacke
Universitꢀt Wꢁrzburg, Institut fꢁr Anorganische Chemie
Am Hubland, 97074 Wꢁrzburg (Germany)
Fax : (+49)931-888-4609
(SiSe2O2C skeletons), 7 (SiSe2S2C skeleton), and 8 and 10
(SiSe4C skeletons). The synthesis of these compounds was
realized by using the “zwitterion trick” (in this context, see
ref. [4c]). Compounds 8 and 10 are especially remarkable as
they contain one carbon ligand atom and four soft selenium
E-mail: r.tacke@mail.uni-wuerzburg.de
Chem. Eur. J. 2009, 15, 7329 – 7338
ꢂ 2009 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
7329

ligand atoms bound to the hard silicon(IV) coordination
center, and 10 is even stable in solution.
lent each of phenol (instead of benzenethiol or benzenesele-
nol) and triethylamine afforded 5 (54% yield). The crystal-
line bulk material was a mixture of two diastereomers, one
of which was characterized by single-crystal X-ray diffrac-
tion.
Results and Discussion
The identities of 1·CH3CN, 2·CH3CN, 3, and 5 were estab-
lished by elemental analyses, solid- and solution-state NMR
spectroscopy, and crystal structure analyses.
Syntheses: Compounds 1 and 2 were synthesized according
to Scheme 1 by treating the pentacoordinate chlorosili-
Compounds 6–10 were synthesized according to Scheme 3
by treatment of the corresponding trihydridosilanes 12[6a]
and 13[6b] with two molar equivalents of 2-selenylphenol
Scheme 1. Syntheses of compounds 1–3.
ACHTUNGTRENNUNG
ACHTUNGTRENNUNG
equivalent of triethylamine to give the crystalline solids
1·CH3CN (74% yield) and 2·CH3CN (77% yield). Alterna-
tively, compound 1·CH3CN could also be prepared by treat-
ing 11 with S-(trimethylsilyl)benzenethiol (60% yield;
Scheme 1).
Compound 3 was synthesized analogously by treatment of
1 with phenyl trimethylsilyl telluride (Scheme 1) and was
isolated as the extremely air- and moisture-sensitive solvate
3·CH3CN (55% yield). In addition, solvent-free 3 (which is
somewhat more stable) was also prepared by using a modi-
fied crystallization method (69% yield; for details, see the
Experimental Section).
Scheme 3. Syntheses of compounds 6–10.
(14), 2-selenylbenzenethiol (15), and benzene-1,2-diselenol
(16), respectively, as the ligands. The syntheses were per-
formed at 208C by using dichloromethane (9) or acetonitrile
(6–8 and 10) as the solvent. Compounds 6–10 were isolated
as crystalline solids (yields: 6 68%, 7 65%, 8 79%, 9 65%,
10 80%), and their identities were established by elemental
analyses, solid-state NMR spectroscopy, solution-state NMR
spectroscopy (10 only), and crystal structure analyses. Com-
pounds 6–10 are sensitive to moisture and air (oxygen) but
can be stored at 208C under glovebox conditions for a
period of several months.
Surprisingly, compound 11 did not react with trimethyl-
ACHTUNGTRENNUNG(phenoxy)silane under the same conditions used for the syn-
thesis of 1 and 3, and could be reisolated almost quantita-
tively (Scheme 2). Treatment of 11 with one molar equiva-
Ligand 14 was synthesized for the first time, to the best of
our knowledge, and was isolated as an oily liquid (49%
yield; Scheme 4). The syntheses of the known ligands 15 and
Scheme 2. Synthesis of compound 5.
Scheme 4. Syntheses of compounds 14–16.
7330
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ꢂ 2009 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
Chem. Eur. J. 2009, 15, 7329 – 7338

Pentacoordinate Silicon(IV) Complexes
FULL PAPER
16 were carried out according to Scheme 4 by using the pro-
cedure outlined in ref. [7]. Based on this report, we have de-
veloped a detailed and reliable synthetic protocol for the
synthesis of 15 and 16 (yields: 15 65%, 16 54%). The identi-
ties of 14–16 were established by elemental analyses and so-
lution-state NMR spectroscopy. All these ligands are sensi-
tive to air (oxygen) but can be stored at ꢀ208C under an
argon atmosphere over a period of at least 6 months.
chlorosilicon(IV) complex 11 and its iodo and trifluorome-
thanesulfonato derivatives (Cl/I and Cl/OSO2CF3 exchange,
respectively) in which the oxygen and sulfur atoms of the
S,N,O ligand occupy equatorial sites of the trigonal-bipyra-
midal Si coordination polyhedron.[2d] It is reasonable to
assume that this change in stereochemistry, which was also
observed in solution (see below), is mainly based on elec-
tronic effects because the steric demand of the XPh (X=S,
Se, Te) groups is similar to that of the Cl, I, and OSO2CF3 li-
gands.
Crystal structure analyses: Compounds 1·CH3CN, 2·CH3CN,
3, and 5–10 were structurally characterized by single-crystal
X-ray diffraction. The crystal data and experimental param-
eters used for the crystal structure analyses are given in
Tables 1 and 2. The molecular structures of 1–3 and 5–10 in
the crystal are shown in Figures 1–4; selected bond lengths
and angles are given in the respective legends.
The Si coordination polyhedra of the pentacoordinate sili-
con(IV) complexes 1–3 are distorted trigonal bipyramids,
with the oxygen and sulfur atoms of the tridentate S,N,O
ligand in the axial positions (see Figure 1). The S-Si-O
angles range from 167.90(4) to 170.23(4)8, and the sum of
the equatorial bond angles amounts to between 359.3 and
359.78. The coordination mode of the tridentate ligand of 1–
3 is totally different from that observed for the related
ꢀ
The Si XPh bond lengths for 1·CH3CN (X=S), 2·CH3CN
(X=Se), and 3 (X=Te) are 2.1881(6), 2.3201(3), and
2.5184(4) ꢃ, respectively. These bond lengths are very simi-
ꢀ
lar to the respective sums of the covalent radii (Si S 2.21,
[8]
ꢀ
ꢀ
ꢀ
Si Se 2.34, Si Te 2.54 ꢃ). The Si Se bond length of
ꢀ
2·CH3CN (2.3201(3) ꢃ) is similar to the equatorial Si Se
bond lengths observed for compounds
6
and 8–10
(2.2846(4)–2.3439(8) ꢃ; see below). Pentacoordinate silicon
ꢀ
ꢀ
compounds with Si Se and Si Te bonds have not yet been
described in the literature. As can be seen from Table 3, ex-
change of the XPh (X=S, Se, Te) group of 1·CH3CN,
ꢀ
ꢀ
2·CH3CN, and 3 only slightly affects the analogous Si S, Si
ꢀ
ꢀ
O, Si N, and Si C bond lengths of these compounds. In con-
trast, replacement of the chloro ligand of 11 by an iodo or
Table 1. Crystallographic data for compounds 1·CH3CN, 2·CH3CN, 3, and 5–8.
1·CH3CN
2·CH3CN
3
5
6
7
8
formula
Mr [gmolꢀ1
T [K]
C25H24N2OS2Si C25H24N2OSSeSi C23H21NOSSiTe
C23H21NO2SSi C20H19NO2Se2Si C20H19NS2Se2Si C20H19NSe4Si
]
460.67
507.57
515.16
403.56
491.37
523.49
617.29
193(2)
98(2)
101(2)
193(2)
193(2)
193(2)
193(2)
l
G
0.71073
monoclinic
P21/c (14)
7.2119(8)
24.155(3)
14.1455(14)
98.370(12)
2438.0(5)
4
0.71073
monoclinic
P21/c (14)
7.1535(2)
23.9810(6)
14.1167(3)
98.3670(10)
2395.92(10)
4
0.71073
monoclinic
P21/n (14)
7.3408(2)
16.8311(4)
17.9108(4)
94.3530(10)
2206.56(9)
4
0.71073
monoclinic
C2/c (15)
19.813(3)
12.2057(11)
19.693(4)
119.008(18)
4165.0(11)
8
0.71073
monoclinic
P21/c (14)
9.938(2)
12.996(3)
15.330(3)
95.67(3)
1970.2(7)
4
0.71073
monoclinic
P21/c (14)
10.240(2)
13.637(3)
15.604(3)
106.08(3)
2093.6(7)
4
0.71073
orthorhombic
P212121 (19)
6.5504(13)
16.095(3)
20.240(4)
90
2133.9(7)
4
1.921
crystal system
space group (no.)
a [ꢃ]
b [ꢃ]
c [ꢃ]
b [8]
V [ꢃ3]
Z
1calcd [gcmꢀ3
1.255
0.287
1.407
1.724
1.551
1.510
1.287
0.231
1.657
3.828
1.661
3.793
m [mmꢀ1
6.938
F000
968
1040
1024
1696
976
1040
1184
crystal dimensions [mm]
2q range [8]
index ranges
0.5ꢄ0.3ꢄ0.3
5.70–58.18
ꢀ9ꢁhꢁ9
ꢀ32ꢁkꢁ33
ꢀ19ꢁlꢁ19
30843
0.30ꢄ0.10ꢄ0.09 0.204ꢄ0.176ꢄ0.096 0.5ꢄ0.4ꢄ0.4 0.5ꢄ0.5ꢄ0.4
0.6ꢄ0.2ꢄ0.08
5.10–58.28
ꢀ13ꢁhꢁ13
ꢀ18ꢁkꢁ18
ꢀ21ꢁlꢁ21
29679
0.40ꢄ0.25ꢄ0.25
4.76–58.10
ꢀ8ꢁhꢁ8
ꢀ21ꢁkꢁ21
ꢀ27ꢁlꢁ27
30820
3.38–72.56
ꢀ11ꢁhꢁ11
ꢀ39ꢁkꢁ39
ꢀ22ꢁlꢁ23
63367
3.32–66.2
ꢀ11ꢁhꢁ11
ꢀ25ꢁkꢁ25
ꢀ27ꢁlꢁ27
97838
5.26–58.14
ꢀ26ꢁhꢁ26
ꢀ16ꢁkꢁ16
ꢀ26ꢁlꢁ26
26049
5.34–58.26
ꢀ13ꢁhꢁ13
ꢀ17ꢁkꢁ17
ꢀ20ꢁlꢁ20
32768
reflns collected
independent reflns
Rint
6404
0.0382
11551
8362
5514
5250
5143
0.0585
5584
0.0404
0.0527
0.0636
0.0463
0.0798
restraints
43
151
0
0
0
114
0
parameters
315
1.054
363
1.031
255
1.080
0.0232/1.5920
0.0255
0.0628
255
1.033
240
1.037
230
1.058
0.0386/2.0312
0.0405
0.0956
240
1.075
0.0319/0.2462
0.0238
0.0564
S[a]
weight parameters a/b[b]
0.0399/1.0736 0.0409/0.6952
0.0396
0.0957
0.0719/0.6613 0.0563/0.0000
0.0427
0.1231
[c]
R1 [I>2s(I)]
0.0348
0.0873
0.0337
0.0919
wR2[d] (all data)
absolute structur
parameter
ꢀ0.008(9)
max/min residual electron
0.336/ꢀ0.235
0.985/ꢀ0.346
1.916/ꢀ0.563
0.492/ꢀ0.251 0.876/ꢀ1.002
0.665/ꢀ0.403
0.527/ꢀ0.425
density [eꢃꢀ3
]
2
2
2
[a] S={S[w
(Fo ꢀFc2)2]/
E
E
(Fo ,0)+2Fc2]/3. [c] R1 =
2
2
SjjFo jꢀjFc jj/SjFo j. [d] wR2 ={S[w
U
(Fo )2]}0.5
ACHTUNGTERNNUNG .
Chem. Eur. J. 2009, 15, 7329 – 7338
ꢂ 2009 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
www.chemeurj.org
7331

R. Tacke et al.
Table 2. Crystallographic data for compounds 9 and 10.
9
10
formula
Mr [gmolꢀ1
T [K]
C17H19NO3Se2Si C17H19NOSe4Si
]
471.34
597.26
100(2)
193(2)
l
N
0.71073
orthorhombic
Pbca (61)
19.255(4)
9.2112(18)
20.130(4)
90
3570.3(12)
8
1.754
0.71073
monoclinic
P21/c (14)
13.8787(18)
11.6100(12)
13.0991(17)
103.679(15)
2050.8(4)
4
crystal system
space group (no.)
a [ꢃ]
b [ꢃ]
c [ꢃ]
b [8]
V [ꢃ3]
Z
1calcd [gcmꢀ3
1.934
7.218
m [mmꢀ1
4.225
F000
1872
1144
crystal dimensions [mm]
2q range [8]
index ranges
0.2ꢄ0.15ꢄ0.08 0.5ꢄ0.4ꢄ0.3
4.04–66.66
ꢀ29ꢁhꢁ29
ꢀ14ꢁkꢁ14
ꢀ30ꢁlꢁ30
216549
4.62–58.24
ꢀ18ꢁhꢁ18
ꢀ15ꢁkꢁ15
ꢀ17ꢁlꢁ17
27916
reflns collected
independent reflns
Rint
6860
5447
0.0541
0.0418
restraints
0
0
parameters
220
1.073
0.0225/1.9603
0.0185
0.0494
228
1.013
0.0320/0.0525
0.0253
0.0574
S[a]
weight parameters a/b[b]
[c]
R1 [I>2s(I)]
wR2[d] (all data)
max/min residual electron density
0.585/ꢀ0.300
0.482/ꢀ0.552
[eꢃꢀ3
]
2
[a] S={S[w
parameters.
G
ACHTUNGTRENNUNG
2
2
[b] wꢀ1 =s
2(Fo )+(aP)2 +bP;
P=[maxACHNUTGTRENNUNG
2
2
[c] R1 =SjjFo jꢀjFc jj/SjFo j. [d] wR2 ={S[w
E
(Fo )2]}0.5
.
trifluoromethanesulfonato ligand significantly affects these
bond lengths.[2d]
Compound 5 has a slightly distorted tetrahedral Si coordi-
nation polyhedron, with X-Si-X (X=C, N, O) angles in the
Figure 1. Molecular structures of a) 1 in the crystal of 1·CH3CN, b) 2 in
the crystal of 2·CH3CN, and c) 3; displacement ellipsoids drawn at the
ꢀ
range of 104.05(7) to 114.34(7)8 and Si X bond lengths
ꢀ
shorter than those in the pentacoordinate compounds
1·CH3CN, 2·CH3CN, and 3 (see Figure 2).
50%probability level. Selected bond lengths [ꢃ] and angles [8] for 1: Si
ꢀ
ꢀ
ꢀ
ꢀ
S1 2.2935(6), Si S2 2.1881(6), Si O 1.7676(10), Si N 1.8592(12), Si C1
1.8782(16); S1-Si-S2 81.89(2), S1-Si-O 167.90(4), S1-Si-N 84.85(4), S1-Si-
C1 98.87(5), S2-Si-O 92.85(4), S2-Si-N 127.66(4), S2-Si-C1 121.65(5), O-
Si-N 89.86(5), O-Si-C1 93.17(6), N-Si-C1 110.33(6). Selected bond lengths
The Si coordination polyhedra of the zwitterionic penta-
coordinate silicon(IV) complexes 6 and 8–10 are distorted
trigonal bipyramids (trigonal bipyramid!square pyramid
transition: 6 24.2% (pivot atom: C1), 8 10.8% (pivot atom:
Se3), 9 8.5% (pivot atom: C1), 10 16.9% (pivot atom:
C1)),[9] in which each bidentate ligand spans one axial and
one equatorial site (see Figure 3 and Table 4). The Si coordi-
nation polyhedron of 7 is a somewhat distorted square pyra-
mid, with the carbon ligand in the apical position (see Fig-
ure 4a).
ꢀ
ꢀ
ꢀ
[ꢃ] and angles [8] for 2: Si Se 2.3201(3), Si S 2.2893(4), Si O 1.7644(8),
ꢀ
ꢀ
Si N 1.8545(10), Si C1 1.8757(12); Se-Si-S 81.793(13), Se-Si-O 92.76(3),
Se-Si-N 125.76(3), Se-Si-C1 122.29(4), S-Si-O 168.68(3), S-Si-N 85.09(3),
S-Si-C1 98.48(4), O-Si-N 90.15(4), O-Si-C1 92.82(5), N-Si-C1 111.61(5).
ꢀ
ꢀ
Selected bond lengths [ꢃ] and angles [8] for 3: Si Te 2.5184(4), Si S
ꢀ
ꢀ
ꢀ
2.3248(5), Si O 1.7774(11), Si N 1.8431(13), Si C1 1.8757(14); Te-Si-S
82.424(15), Te-Si-O 93.77(4), Te-Si-N 125.14(4), Te-Si-C1 126.01(5), S-Si-
O 170.23(4), S-Si-N 84.51(4), S-Si-C1 95.47(5), O-Si-N 90.42(5), O-Si-C1
94.04(6), N-Si-C1 108.13(6).
In the case of 6 (SiSe2O2C skeleton), the oxygen atoms
O1 and O2 occupy the axial positions, in accordance with
the VSEPR concept. In contrast, compound 9 (SiSe2O2C
skeleton), which differs from 1 only in the (ammonio)or-
ganyl group, shows a non-VSEPR structure, with the seleni-
um atom Se2 and the oxygen atom O1 in the axial positions
(in this context, see ref. [4c]).
ꢀ
As can be seen from Table 4, the equatorial Si Se bond
lengths of 6 and 8–10 are in the range of 2.2846(4) to
2.3439(8) ꢃ. These bond lengths are very similar to the sum
of the covalent radii of silicon and selenium (2.34 ꢃ),[8]
ꢀ
whereas the axial Si Se bond lengths are significantly
longer (2.4585(9)–2.5797(4) ꢃ). The longest axial Si Se
ꢀ
7332
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ꢂ 2009 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
Chem. Eur. J. 2009, 15, 7329 – 7338

Pentacoordinate Silicon(IV) Complexes
FULL PAPER
ꢀ
Table 3. Comparison of the Si X (X=S, O, N, C) bond lengths [ꢃ] of
1·CH3CN, 2·CH3CN, and 3.
Table 4. Selected bond lengths [ꢃ] and angles [8] of compounds 6 and 8–
10.
ꢀ
Si X
1·CH3CN
2·CH3CN
3
6
8
9
10
[a]
ꢀ
ꢀ
Si S
2.2935(6)
1.7676(10)
1.8592(12)
1.8782(16)
2.2893(4)
1.7644(8)
1.8545(10)
1.8757(12)
2.3248(5)
1.7774(11)
1.8431(13)
1.8757(14)
Si Seax
2.4585(9),
2.5049(9)
2.2957(9),
2.3051(10)
2.5797(4)
2.4715(7),
2.5088(7)
2.2935(7),
2.2988(7)
ꢀ
Si O
ꢀ
ꢀ
Si N
Si Seeq
2.3221(8),
2.3439(8)
1.7669(17),
1.7874(16)
2.2846(4)
1.7419(8)
ꢀ
Si C1
ꢀ
Si Oax
ꢀ
[a] Si S1 for 1·CH3CN.
ꢀ
Si Oeq
ꢀ
Si C
1.6798(8)
1.9183(11)
176.60(3)[c]
1.919(2)
1.917(3)
1.928(2)
Xax-Si-Yax
171.92(9)[a]
175.43(4)[b]
173.84(3)[b]
[a] X, Y=O. [b] X, Y=Se. [c] X=Se, Y=O.
bond lengths were observed for 9 (2.5797(4) ꢃ) and 10
(2.5088(7) ꢃ), which can be explained by the intramolecular
ꢀ
N H···Se hydrogen bonds (see Figures 3c and 3d). In the
ꢀ
case of 6, an intramolecular N H···O hydrogen bond also
ꢀ
leads to a strong differentiation between the two axial Si O
bond lengths (1.7669(17) vs. 1.7874(16) ꢃ; see Figure 3a).
The four basal ligand atoms of the slightly distorted
square-pyramidal Si coordination polyhedron of 7 are disor-
dered in the crystal. Due to the similar covalent radii and
electronegativities of sulfur and selenium, these ligand
atoms can replace each other leading to different isomers.
The major isomer (occupancy about 70%) is depicted in
Figure 4a; the possible minor isomers (total occupancy
about 30%) are shown in Figure 4b. As expected, the two
Figure 2. Molecular structure of 5 (displacement ellipsoids drawn at the
ꢀ
50% probability level). Selected bond lengths [ꢃ] and angles [8]: Si O1
ꢀ
ꢀ
ꢀ
1.6375(13), Si O2 1.6327(12), Si N 1.7159(13), Si C1 1.8437(18); O1-Si-
O2 108.25(7), O1-Si-N 104.05(7), O1-Si-C1 113.33(7), O2-Si-N 114.34(7),
O2-Si-C1 105.68(7), N-Si-C1 111.38(7).
Figure 3. Molecular structures of a) 6, b) 8, c) 9, and d) 10; displacement ellipsoids drawn at the 50% probability level. Selected bond lengths [ꢃ] and
ꢀ
ꢀ
ꢀ
ꢀ
ꢀ
angles [8] for 6: Si Se1 2.3439(8), Si Se2 2.3221(8), Si O1 1.7669(17), Si O2 1.7874(16), Si C1 1.919(2); Se1-Si-Se2 128.00(3), Se1-Si-O1 89.40(6), Se1-
Si-O2 88.10(6), Se1-Si-C1 113.35(7), Se2-Si-O1 85.82(6), Se2-Si-O2 89.68(6), Se2-Si-C1 118.63(7), O1-Si-O2 171.92(9), O1-Si-C1 93.75(9), O2-Si-C1
ꢀ
ꢀ
ꢀ
94.30(9). Intramolecular N H···O2 hydrogen bond: N H 0.86(4), H···O2 1.96(3), N···O2 2.713(3), N H···O2 146(3). Selected bond lengths [ꢃ] and angles
ꢀ
ꢀ
ꢀ
ꢀ
ꢀ
[8] for 8: Si Se1 2.5049(9), Si Se2 2.3051(10), Si Se3 2.2957(9), Si Se4 2.4585(9), Si C1 1.917(3); Se1-Si-Se2 89.49(3), Se1-Si-Se3 92.44(3), Se1-Si-Se4
175.43(4), Se1-Si-C1 88.13(9), Se2-Si-Se3 120.73(4), Se2-Si-Se4 86.64(3), Se2-Si-C1 123.16(11), Se3-Si-Se4 91.62(3), Se3-Si-C1 116.11(11), Se4-Si-C1
ꢀ
ꢀ
ꢀ
91.95(10). Intramolecular bifurcated N H···Se1/Se2 hydrogen bond: N H 0.84(5), H···Se1 2.76(5), N···Se1 3.364(3), H···Se2 2.85(5), N···Se2 3.595(3), N
ꢀ
ꢀ
ꢀ
ꢀ
H···Se1 130(4), N H···Se2 149(4), Se1···H···Se2 74.3(12). Selected bond lengths [ꢃ] and angles [8] for 9: Si Se1 2.2846(4), Si Se2 2.5797(4), Si O1
ꢀ
ꢀ
1.7419(8), Si O2 1.6798(8), Si C1 1.9183(11); Se1-Si-Se2 86.308(17), Se1-Si-O1 91.25(3), Se1-Si-O2 121.78(3), Se1-Si-C1 121.88(4), Se2-Si-O1 176.60(3),
Se2-Si-O2 86.64(3), Se2-Si-C1 93.57(3), O1-Si-O2 92.65(4), O1-Si-C1 89.73(4), O2-Si-C1 116.21(5). Intramolecular N H···Se2 hydrogen bond: N H
0.908(18), H···Se2 2.407(18), N···Se2 3.1404(10), N H···Se2 137.8(15). Selected bond lengths [ꢃ] and angles [8] for 10: Si Se1 2.5088(7), Si Se2 2.2988(7),
ꢀ
ꢀ
ꢀ
ꢀ
ꢀ
ꢀ
ꢀ
ꢀ
Si Se3 2.2935(7), Si Se4 2.4715(7), Si C1 1.928(2); Se1-Si-Se2 91.61(2), Se1-Si-Se3 83.67(2), Se1-Si-Se4 173.84(3), Se1-Si-C1 96.01(7), Se2-Si-Se3
ꢀ
125.79(3), Se2-Si-Se4 87.39(3), Se2-Si-C1 116.12(8), Se3-Si-Se4 91.99(2), Se3-Si-C1 118.09(8), Se4-Si-C1 89.88(7). Intramolecular N H···Se1 hydrogen
ꢀ
ꢀ
bond: N H 0.87(4), H···Se1 2.49(4), N···Se1 3.209(2), N H···Se1 140(3).
Chem. Eur. J. 2009, 15, 7329 – 7338
ꢂ 2009 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
www.chemeurj.org
7333

R. Tacke et al.
Scheme 5. Equilibrium reactions of compounds 1–3 and 5 in solution (A:
pentacoordination; B: tetracoordination).
Table 5. Solution-state 29Si NMR spectroscopic data [ppm] of compounds
1–3 and 5.[a]
d29Si (A)
d29Si (B)[b]
A/B ratio[c]
1
2
3
5
ꢀ79.7
ꢀ82.7
ꢀ93.3
–
ꢀ23.8, ꢀ22.2
ꢀ20.5, ꢀ18.4
–
ꢀ56.4, ꢀ56.2
75:25
93:7
traces of B
0:100
[a] Solvent CD2Cl2, T=238C. [b] Two diastereomers. [c] Ratios deter-
1
mined by H NMR spectroscopy.
Figure 4. a) Molecular structure of the major isomer of 7 (displacement
ellipsoids drawn at the 50% probability level). Selected bond lengths [ꢃ]
ꢀ
ꢀ
ꢀ
ꢀ
and angles [8]: Si Se1 2.378(3), Si Se2 2.381(2), Si S1 2.208(8), Si S2
ꢀ
2.245(9), Si C31 1.916(3); Se1-Si-Se2 83.09(7), Se1-Si-S1 89.7(3), Se1-Si-
1
within the experimental detection limits; however, H NMR
S2 154.0(3), Se1-Si-C31 103.65(12), Se2-Si-S1 147.5(4), Se2-Si-S2 89.1(3),
spectroscopy experiments indicate that traces of the tetra-
coordinate species exist. On the other hand, when com-
pound 5 (Si–OPh) was dissolved, only the tetracoordinate
species B could be detected. These results indicate that the
chalcogen atoms stabilize the pentacoordination in the fol-
lowing order: Te>Se>S>O; that is, the softer the chalco-
gen ligand atom, the more favored the pentacoordinate spe-
cies A is. This is in sharp contrast to what one would expect
if it is assumed that hard ligand atoms should favor penta-
coordination of the hard silicon(IV) coordination center
(O>S>Se>Te).
Se2-Si-C31 104.22(11), S1-Si-S2 83.7(4), S1-Si-C31 108.3(4), S2-Si-C31
ꢀ
ꢀ
102.3(3). Intramolecular bifurcated N H···S1/S2 hydrogen bond: N H
0.96(6), H···S1 2.45(6), N···S1 3.307(12), H···S2 2.61(6), N···S2 3.319(12),
ꢀ
ꢀ
N H···S1 148(4), N H···S2 131(4), S1···H···S2 71.8(16). b) Coordination
polyhedra of the three possible minor isomers of 7 in the crystal.
ꢀ
Si Se bond lengths of the major isomer of 7 (2.378(3) and
2.381(2) ꢃ) are somewhat longer in the equatorial case and
ꢀ
shorter in the axial case than the Si Se bond lengths of 6
and 8–10.
Solid- and solution-state NMR spectroscopic studies: Com-
pounds 1·CH3CN, 2·CH3CN, and 3 were characterized by
solid-state 13C, 15N, 29Si, 77Se (2·CH3CN only), and 125Te (3
only) NMR spectroscopy (see the Experimental Section).
The isotropic 29Si chemical shifts obtained in the solid-state
VACP/MAS NMR measurements reflect the presence of
pentacoordinate silicon atoms (1·CH3CN d=ꢀ79.3,
2·CH3CN ꢀ82.6, 3 ꢀ90.6 ppm). These 29Si chemical shifts
are very similar to those obtained in solution (solvent
CD2Cl2; 1 d=ꢀ79.7, 2 ꢀ82.7, 3 ꢀ93.3 ppm) indicating simi-
lar structures in the solid state and in solution. The
29Si NMR spectra of 2·CH3CN show 77Se satellites with
1J(29Si,77Se) coupling constants of 121 (solid state) and
The ratio of A/B also depends on the solvent. Less polar
solvents (such as C6D6) favor the tetracoordinate species B
(e.g., compound 1, A/B ca. 35:65), whereas more polar sol-
vents (such as CD3CN) favor the pentacoordinate species A.
However, the NMR spectrum of 5 in CD3CN did not indi-
cate the existence of a pentacoordinate species.
Compounds 6–10 were also characterized by solid-state
13C, 15N, 29Si, and 77Se NMR spectroscopy (see Table 6 and
the Experimental Section). The NMR spectra obtained are
in agreement with the crystal structures of 6–10. The solid-
state 29Si NMR spectrum of 7 (Figure 5, left) does not reflect
the four different isomeric structures found in the crystal.
Probably because of the similar isotropic chemical shifts of
ꢀ
132 Hz (solution), thus confirming the existence of an Si Se
bond.[10] Likewise, the 29Si VACP/MAS NMR spectrum of 3
1
Table 6. Solid-state 29Si and 77Se NMR spectroscopic data [ppm] of com-
pounds 6–10.
shows 125Te satellites with a J(29Si,125Te) coupling constant
of 397 Hz; however, these satellites could not be detected in
d29Si
d77Se
solution.[11]
6
ꢀ68.2
ꢀ66.6
ꢀ70.7
ꢀ107.9
ꢀ72.1
ꢀ99.6
ꢀ31.4, ꢀ17.2
Solution-state NMR spectroscopic studies (solvent
CD2Cl2) of 1 (Si–SPh) and 2 (Si–SePh) revealed the exis-
tence of a dynamic equilibrium between the pentacoordi-
nate species A and the tetracoordinate species B (Scheme 5,
Table 5). In the case of 3 (Si–TePh), only the pentacoordi-
nate species A could be detected in the 29Si NMR spectrum
7[a]
7[b]
8
224.6, 255.8
199.1, 234.7
249.1, 285.1, 367.5, 411.1
28.3, 60.7
9
10
204.9, 264.8, 275.6, 299.9
[a] Relative intensity 92%. [b] Relative intensity 8%.
7334
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ꢂ 2009 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
Chem. Eur. J. 2009, 15, 7329 – 7338

Pentacoordinate Silicon(IV) Complexes
FULL PAPER
this series of compounds, pentacoordination with chalcogen
ligand atoms is favored in the following order: Te>Se>S>
O; that is, the softer the chalcogen ligand atom, the more fa-
vored pentacoordination is. This contrasts sharply with the
widely held view that pentacoordination of the hard sili-
AHCTUNGTREGcNNUN on(IV) coordination center is favored by hard ligand
atoms. Obviously, this classical concept is too simple to ex-
plain the trend found for this particular series of com-
pounds.
The high potential of soft ligand atoms to form stable
pentacoordinate silicon(IV) complexes is further supported
by the synthesis of compounds 6–10, which have SiSe2O2C
(6, 9), SiSe2S2C (7), or SiSe4C skeletons (8, 10). Based on
the approach reported here, the synthesis of further silicon–
selenium compounds of this type, with other element combi-
nations in the silicon coordination sphere, should be possi-
ble. These compounds can serve as a platform to extend our
knowledge about the stereochemistry and bonding situation
of pentacoordinate silicon(IV) complexes with soft ligand
atoms.
Figure 5. 29Si NMR spectra of compounds 7 (left; solid state) and 10
(right; in solution, solvent CD2Cl2).
these isomers (with shift differences similar to the linewidth
of the resonance signals detected), only two signals at d=
ꢀ66.6 and ꢀ70.7 ppm could be observed (estimated ratio,
92:8).
The selenium compounds 14–16, for which reliable syn-
thetic protocols have been developed, are also very promis-
ing ligand systems for studying the coordination chemistry
of other elements.
All attempts to characterize compounds 6–9 by solution-
state NMR spectroscopy failed owing to their poor solubility
in common organic solvents, but compound 10 was suitable
1
for solution-state studies (solvent CD2Cl2) by H, 13C, 29Si,
and 77Se NMR spectroscopy. The isotropic 29Si chemical shift
of 10 (d=ꢀ98.1 ppm; Figure 5, right) is very similar to that
obtained in the 29Si VACP/MAS NMR experiment (d=
ꢀ99.6 ppm), indicating that 10 exists in solution as well. The
A2X spin system observed for the SiC(HA)2NHX protons of
10 in the temperature range of 23 to ꢀ958C indicates that
the L and D enantiomers are not configurationally stable on
the NMR time scale. The 29Si NMR spectra of 10 show sele-
nium satellites in the solid state and in solution, which clear-
Experimental Section
General procedures: All syntheses were carried out under dry argon. The
organic solvents used were dried and purified according to standard pro-
cedures and stored under nitrogen. Compound 11 was synthesized ac-
cording to ref. [2d], and phenyl trimethylsilyl telluride was synthesized
according to known procedures by treating tellurium powder with phe-
nyllithium,[12] followed by treatment with chlorotrimethylsilane.[13] The so-
lution-state 1H, 13C, 29Si, 77Se, and 125Te NMR spectra were recorded at
238C by using a Bruker DRX-300 (1H 300.1 MHz, 13C 75.5 MHz, 29Si
59.6 MHz, 77Se 57.2 MHz; 14–16) or a Bruker Avance 500 NMR spec-
trometer (1H 500.1 MHz, 13C 125.8 MHz, 29Si 99.4 MHz, 77Se 95.4 MHz,
125Te 157.8 MHz; 1–3, 5, and 10), with CD2Cl2 as the solvent. Chemical
shifts were determined relative to internal CDHCl2 (1H; d=5.32 ppm),
internal CD2Cl2 (13C; d=53.8 ppm), external TMS (29Si; d=0 ppm), ex-
ternal Me2Se with 5% C6D6 (77Se; d=0 ppm), or an external solution of
Ph2Te2 (0.1m) in CDCl3 (125Te ; d=422 ppm). Assignment of the 13C NMR
spectroscopic data was supported by DEPT135 experiments. Solid-state
13C, 15N, 29Si, and 77Se VACP/MAS NMR spectra and 125Te{1H} HPDec/
MAS NMR spectra were recorded at 228C by using a Bruker DSX-400
NMR spectrometer with bottom layer rotors of ZrO2 (diameter 7 mm)
containing about 300 mg of sample (13C 100.6 MHz, 15N 40.6 MHz, 29Si
79.5 MHz, 77Se 76.3 MHz, 125Te 126.2 MHz; external standard TMS (13C,
29Si; d=0 ppm), glycine (15N; d=ꢀ342.0 ppm), Me2Se (77Se; d=0 ppm),
ly indicates the presence of covalent Si Se bonds. The 77Se
ꢀ
chemical shift of 10 in solution (d=243.3 ppm) is very simi-
lar to the average of the four isotropic 77Se chemical shifts
measured in the solid state (d=204.9, 264.8, 275.6,
299.9 ppm; average d=261.3 ppm). In this context, it should
be mentioned that the 77Se nucleus is a very sensitive probe;
as can be seen from Table 6, the isotropic 77Se chemical
shifts of the structurally related compounds 6–10 range from
d=ꢀ31.4 (6, SiSe2O2C skeleton) to 411.1 ppm (8, SiSe4C
skeleton).
or Te(OH)6 (
125Te ; d=685.5 and 692.2 ppm); contact time 1–2 ms (13C),
Conclusion
3 ms (15N), 3–5 ms (29Si), or 5 ms (77Se); 908 1H transmitter pulse length
3.6 ms; repetition time 4 s).
With the synthesis of the pentacoordinate silicon(IV) com-
Synthesis of 1·CH3CN
plexes
ACHTUNGTRENNUNG
1 (SiS2ONC skeleton), 2 (SiSeSONC), and 3
Method A: Triethylamine (234 mg, 2.31 mmol) and benzenethiol (255 mg,
2.31 mmol) were sequentially added in single portions to a stirred solu-
tion of 11 (800 mg, 2.31 mmol) in tetrahydrofuran (20 mL) at 208C and
the reaction mixture was stirred for 30 min at 208C. The resulting solid
was filtered off, washed with tetrahydrofuran (5 mL), and discarded. The
solvent of the filtrate (including the wash solution) was removed in
vacuo, then acetonitrile (5 mL) was added to the solid residue, and the
resulting solution was allowed to stand at ꢀ208C for 2 h. The precipitate
of silicon with soft chalcogen ligand atoms (S, Se, Te) is pos-
sible. These compounds exist in the solid state and in solu-
tion. Quite surprisingly, the corresponding oxygen analogue
4 (SiSO2NC skeleton) could not be synthesized, and the tet-
racoordinate silicon compound 5 was obtained instead. In
Chem. Eur. J. 2009, 15, 7329 – 7338
ꢂ 2009 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
www.chemeurj.org
7335

R. Tacke et al.
was dissolved (heating at ca. 608C), and the resulting solution was then
allowed to stand at 208C for 3 h and then at ꢀ208C for a further 24 h.
The yellow crystalline product was isolated by filtration, washed with n-
pentane (6 mL), and dried in vacuo (0.01 mbar, 208C, 10 min; yield:
with n-pentane (5 mL), and dried in vacuo (0.01 mbar, 208C, 30 min;
yield: 489 mg, 879 mmol, 55%). Except for additional CH3CN resonance
signals in the 1H and 13C NMR spectra, the solution-state NMR spectro-
scopic data of the product were identical to those of compound 3.
798 mg, 1.73 mmol, 75%).[14] M.p. >1108C (decomp.); 1H NMR:[15] d=
Synthesis of 3: Phenyl trimethylsilyl telluride (502 mg, 1.81 mmol) was
4
1.32 (d, J
G
added in
a single portion to a stirred suspension of 11 (500 mg,
ACTHNUTRGNEUNG
3H; C(N)CH3), 5.84 (q, 4J(1H,1H)=0.3 Hz, 1H; CCHC), 6.93–7.38 and
1.45 mmol) in acetonitrile (8 mL) at 208C and the reaction mixture was
stirred for 30 min at 208C. The undissolved residue was filtered off and
discarded, a few crystals of 3·CH3CN were added to the filtrate (sponta-
neous crystallization), and then the mixture was allowed to stand at 208C
for 4 h and then at 48C for a further 16 h. The orange crystalline product
was isolated by filtration, washed with n-pentane (7 mL), and dried in
vacuo (0.01 mbar, 208C, 2 h; yield: 512 mg, 994 mmol, 69%). M.p. >408C
7.74–7.76 ppm (m, 14H; SC6H4N, SC6H5, SiC6H5); 13C NMR: d=2.0
(CH3CN), 22.9 (C(O)CH3), 23.9 (C(N)CH3), 104.4 (CCHC), 116.9
(CH3CN), 123.0, 123.2, 127.0, 127.5 (2C), 128.0, 128.7 (2C), 129.2, 129.4,
129.6, 134.5 (2C), 135.1 (2C), 136.8, 139.6 and 140.2 (SC6H4N, SC6H5,
SiC6H5), 172.4 (C(N)CH3), 182.3 ppm (C(O)CH3); 29Si NMR: d=
ꢀ79.7 ppm; 13C VACP/MAS NMR: d=0.7 (CH3CN), 23.0 (CCH3), 24.3
(CCH3), 102.9 (CCHC), 119.3 (CH3CN), 123.1, 124.9, 127.1, 129.0, 130.4
134.2, 135.1, 136.3, 137.2, 138.3 and 138.9 (SC6H4N, SC6H5, SiC6H5), 172.1
(C(N)CH3), 181.2 ppm (C(O)CH3); 15N VACP/MAS NMR: d=ꢀ190.3
(SiNC), ꢀ126.5 ppm (CH3CN); 29Si VACP/MAS NMR: d=ꢀ79.3 ppm;
elemental analysis calcd (%) for C25H24N2OS2Si (Mr =460.70): C 65.18, H
5.25, N 6.08, S 13.92; found: C 64.4, H 5.2, N 5.6, S 13.7.[16]
1
4
(decomp.); H NMR: d=1.46 (d, J
(s, 3H; C(N)CH3), 5.92 (q, 4J(1H,1H)=0.3 Hz, 1H; CCHC), 6.95–6.98,
(1H,1H)=0.3 Hz, 3H; C(O)CH3), 2.36
ACHTUNGTRENNUNG
AHCTUNGTRENNUNG
7.05–7.11, 7.20–7.28, and 7.73–7.77 ppm (m, 14H; SC6H4N, TeC6H5,
SiC6H5); 13C NMR: d=23.3 (C(O)CH3), 24.1 (C(N)CH3), 104.4 (CCHC),
116.5, 123.28, 123.30, 127.4, 127.5 (2C), 128.2, 128.8, 128.9 (2C), 129.5,
134.5 (2C), 137.9, 140.5, 140.6 (2C), and 140.7 (SC6H4N, TeC6H5,
SiC6H5), 173.0 (C(N)CH3), 181.9 ppm (C(O)CH3); 29Si NMR: d=
ꢀ93.3 ppm (125Te satellites not detected); 125Te NMR: d=105.6 ppm; 13C
VACP/MAS NMR: d=21.3 (CCH3), 24.4 (CCH3), 104.0 (CCHC), 115.0,
125.4, 127.9, 129.5, 130.5, 131.4, 138.2, 139.4, and 141.8 (SC6H4N, TeC6H5,
SiC6H5), 172.5 (C(N)CH3), 182.2 ppm (C(O)CH3); 29Si VACP/MAS
NMR: d=ꢀ90.6 ppm (125Te satellites, 1J(29Si,125Te) =397 Hz); 125Te{1H}
HPDec/MAS NMR: d=75 ppm; elemental analysis calcd (%) for
C23H21NOSSiTe (Mr =515.18): C 53.62, H 4.11, N 2.72, S 6.22; found: C
53.1, H 4.1, N 2.8, S 6.3.
Method B: S-(Trimethylsilyl)benzenethiol (329 mg, 1.80 mmol) was
added in
a single portion to a stirred suspension of 11 (500 mg,
1.45 mmol) in acetonitrile (9 mL) at 208C and the reaction mixture was
stirred for 30 min at 208C. The undissolved residue was filtered off and
discarded, and the filtrate was allowed to stand at ꢀ208C for 48 h. The
yellow crystalline product was isolated by filtration, washed with n-pen-
tane (7 mL), and dried in vacuo (0.01 mbar, 208C, 10 min; yield: 402 mg,
873 mmol, 60%). The analytical data of the product were identical to
those obtained for the product synthesized via Method A.
Synthesis of 2·CH3CN: Triethylamine (176 mg, 1.74 mmol) and benzene-
selenol (272 mg, 1.73 mmol) were sequentially added in single portions to
a stirred solution of 11 (600 mg, 1.73 mmol) in tetrahydrofuran (15 mL)
at 208C and the reaction mixture was stirred for 30 min at 208C. The re-
sulting solid was filtered off, washed with tetrahydrofuran (5 mL), and
discarded. The solvent of the filtrate (including the wash solution) was
removed in vacuo, then acetonitrile (3 mL) was added to the solid resi-
due, and the resulting solution was allowed to stand at ꢀ208C for 2 h
before addition of acetonitrile (5 mL). The precipitate was dissolved
(heating of the mixture to ca. 608C), and the resulting solution was al-
lowed to stand at 208C for 4 h and then at ꢀ208C for a further 16 h. The
yellow–orange crystalline product was isolated by filtration, washed with
n-pentane (6 mL), and dried in vacuo (0.01 mbar, 208C, 1 h; yield:
Synthesis of 5: A solution of phenol (272 mg, 2.89 mmol) in tetrahydro-
furan (5 mL) was added dropwise over 5 min to a stirred suspension of
11 (1.00 g, 2.89 mmol) and triethylamine (293 mg, 2.90 mmol) in tetrahy-
drofuran (20 mL) at 208C and the reaction mixture was stirred for
30 min at 208C. The resulting solid was filtered off, washed with tetrahy-
drofuran (5 mL), and discarded. The solvent of the filtrate (including the
wash solution) was removed in vacuo, the residue was dissolved in n-pen-
tane (10 mL), the resulting mixture was stirred at 208C for 10 min, and
the remaining residue was filtered off and discarded. The filtrate was al-
lowed to stand at 48C for 4 h, and then the clear solution was separated
from the oily residue with a syringe and transferred into another flask.
This solution was then allowed to stand at 208C for 4 h (formation of
crystals) and then at ꢀ208C for a further 16 h. The colorless crystalline
product (a mixture of two racemates) was isolated by filtration, washed
with cold (ꢀ208C) n-pentane (5 mL), and dried in vacuo (0.01 mbar,
208C, 3 h; yield: 626 mg, 1.55 mmol, 54%). M.p. >858C (decomp.);
1H NMR (*: resonance signal of the major isomer): d=1.45* (s, 1.8H;
680 mg, 1.34 mmol, 77%).[14] M.p. >808C (decomp.); 1H NMR:[15] d=
4
1.38 (d, J
(1H,1H)=0.3 Hz, 3H; C(O)CH3), 1.96 (s, 3H; CH3CN), 2.35 (s,
3H; C(N)CH3), 5.87 (q, JACHTNUTGRNEUNG
(1H,1H)=0.3 Hz, 1H; CCHC), 6.94–6.97, 7.03–
4
7.08, 7.13–7.16, 7.20–7.30, 7.50–7.52, and 7.74–7.76 ppm (m, 14H;
SC6H4N, SeC6H5, SiC6H5); 13C NMR: d=2.0 (CH3CN), 23.0 (C(O)CH3),
24.0 (C(N)CH3), 104.4 (CCHC), 116.9 (CH3CN), 123.1, 123.3, 127.1,
127.5 (2 C), 128.1, 128.8 (2 C), 129.1, 129.4, 132.9, 134.5 (2 C), 136.3 (2
C), 137.9, 139.8, and 140.2 (SC6H4N, SeC6H5, SiC6H5), 172.7 (C(N)CH3),
182.1 ppm (C(O)CH3); 29Si NMR: d=ꢀ82.7 ppm (77Se satellites,
1J(29Si,77Se)=132 Hz); 77Se NMR: d=161.6 ppm; 13C VACP/MAS NMR:
d=0.9 (CH3CN), 22.9 (CCH3), 25.2 (CCH3), 102.3 (CCHC), 117.4
(CH3CN), 124.9, 125.2, 126.4, 127.4, 128.6, 129.3, 130.0, 130.7, 134.1,
135.1, 136.8, 137.1, and 141.7 (SC6H4N, SeC6H5, SiC6H5), 173.6
(C(N)CH3), 179.5 ppm (C(O)CH3); 15N VACP/MAS NMR: d=ꢀ186.4
(SiNC), ꢀ128.7 ppm (CH3CN); 29Si VACP/MAS NMR: d=ꢀ82.6 ppm
(77Se satellites, 1J(29Si,77Se)=121 Hz); 77Se VACP/MAS NMR: d=
181.9 ppm; elemental analysis calcd (%) for C25H24N2OSSeSi (Mr =
507.59): C 59.16, H 4.77, N 5.52, S 6.32; found: C 58.9, H 4.7, N 5.1, S 6.5.
C(N)CH3), 1.79 (s, 1.2H; C(N)CH3), 1.85 (d, 4J
C(O)CH3), 1.90* (d, 4J(1H,1H)=1.0 Hz, 1.8H; C(O)CH3), 5.04 (q,
4J(1H,1H)=1.1 Hz, 0.4H; CCHC), 5.08* (q, 4J(1H,1H)=1.0 Hz, 0.6H;
(1H,1H)=1.1 Hz, 1.2H;
ACHTUNGTRENNUNG
AHCTUNGTRENNUNG
A
ACHTUNGTRENNUNG
CCHC), 6.69–6.71, 6.76–6.86, 6.95–6.99, 7.08–7.21, 7.31–7.37, 7.45–7.48,
7.53–7.56, 7.59–7.63, 7.70–7.73, and 7.96–7.98 ppm (m, 14H; SC6H4N,
OC6H5, SiC6H5); 13C NMR (*: resonance signals of the major isomer):
d=21.4 (C(O)CH3), 21.6* (C(O)CH3), 34.0* (C(N)CH3), 34.6
(C(N)CH3), 77.5 (NCS), 78.2* (NCS), 106.2* (CCHC), 106.5 (CCHC),
113.3, 114.0*, 119.9 (2C), 120.6* (2C), 122.0, 122.1*, 122.6, 122.7*, 123.0,
123.5*, 125.2*, 125.3, 128.4*, 128.5* (2C), 128.8 (2C), 129.3, 129.68 (2C),
129.75*, 130.0* (2C), 130.3, 131.9*, 132.1, 135.3 (2C), 135.4* (2C),
143.7*, 143.8, 147.3, 147.5*, 153.1, and 153.4* ppm (SC6H4N, OC6H5,
SiC6H5, C(O)CH3); 29Si NMR (*: resonance signal of the major isomer):
d=ꢀ56.4* and ꢀ56.2 ppm; 13C VACP/MAS NMR: d=18.1 (C(O)CH3),
32.1 (C(N)CH3), 76.7 and 77.3 (NCS), 103.4 (CCHC), 113.6, 119.4, 120.6,
121.4, 123.5, 126.8, 127.7, 129.2, 134.3, 141.9, 142.3, 145.1, and 152.1 ppm
(SC6H4N, OC6H5, SiC6H5, C(O)CH3); 15N VACP/MAS NMR: d=
ꢀ285.6 ppm; 29Si VACP/MAS NMR: d=ꢀ57.8 and ꢀ57.4 ppm; elemen-
tal analysis calcd (%) for C23H21NO2SSi (Mr =403.58): C 68.45, H 5.24, N
3.47, S 7.95; found: C 68.3, H 5.2, N 3.5, S 7.9.
Synthesis of 3·CH3CN: Phenyl trimethylsilyl telluride (552 mg,
1.99 mmol) was added in a single portion to a stirred suspension of 11
(550 mg, 1.59 mmol) in acetonitrile (10 mL) at 208C and the reaction
mixture was stirred for 30 min at 208C. The undissolved residue was fil-
tered off and discarded, and the filtrate was then allowed to stand at
ꢀ208C for 2 h (precipitation of a yellow solid). The resulting suspension
was heated to 408C until a clear solution was obtained, which was then
allowed to stand at 208C for 4 h and then at ꢀ208C for a further 16 h.
The yellow–orange crystalline product was isolated by filtration, washed
Synthesis of 6: Compound 12[6a] (173 mg, 1.14 mmol) was added in a
single portion to a stirred solution of 14 (395 mg, 2.28 mmol) in acetoni-
trile (25 mL) at 208C and the reaction mixture was stirred for 20 min
7336
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Chem. Eur. J. 2009, 15, 7329 – 7338

Pentacoordinate Silicon(IV) Complexes
FULL PAPER
(evolution of hydrogen) and then allowed to stand at 208C for 2 d in the
absence of light. The resulting colorless crystalline solid was isolated by
filtration, washed with n-pentane (10 mL), and dried in vacuo (0.01 mbar,
208C, 2 h; yield: 381 mg, 775 mmol, 68%). M.p. >1808C (decomp.); 13C
VACP/MAS NMR: d=44.6 (NCH3), 47.2 (NCH3), 112.8, 114.0, 118.2,
121.7, 122.3, 123.5, 126.5, 126.9, 128.5, 129.5 (2C), 130.3, 130.8, 136.6
(2C), 146.3, 155.6, and 155.9 ppm (SeC6H4O, SiC6H4N); 15N VACP/MAS
NMR: d=ꢀ326.9 ppm; 29Si VACP/MAS NMR: d=ꢀ68.2 ppm (with 77Se
satellites);[17] 77Se VACP/MAS NMR: d=ꢀ31.4, ꢀ17.2 ppm; elemental
analysis calcd (%) for C20H19NO2Se2Si (Mr =491.38): C 48.89, H 3.90, N
2.85; found: C 48.5, H 3.9, N 3.0.
Synthesis of 7: Compound 12[6a] (174 mg, 1.15 mmol) was added in a
single portion to a stirred solution of 15 (434 mg, 2.29 mmol) in acetoni-
trile (10 mL) at 208C and the reaction mixture was stirred for 40 min at
208C (evolution of hydrogen) and then allowed to stand at 208C for 1 d
in the absence of light. Subsequently, the solution was covered with a
layer of n-pentane (5 mL) and then allowed to stand at 208C for two
weeks in the absence of light. The resulting colorless crystalline solid was
isolated by filtration, washed with n-pentane (3ꢄ5 mL), and dried in
vacuo (0.01 mbar, 208C, 3 h; yield: 392 mg, 749 mmol, 65%). M.p.
>1608C (decomp.); 13C VACP/MAS NMR: d=49.6 (br, NCH3) 120–
146 ppm (not well resolved, SeC6H4S, SiC6H4N); 15N VACP/MAS NMR:
d=ꢀ324.9 ppm; 29Si VACP/MAS NMR: ꢀ70.7 (relative intensity 8%),
ꢀ66.6 ppm (relative intensity 92%); 77Se VACP/MAS NMR: d=199.1
and 234.7 (relative intensity 8%), 224.6 and 255.8 ppm (relative intensity
92%); elemental analysis calcd (%) for C20H19NS2Se2Si (Mr =523.52): C
45.89, H 3.66, N 2.68, S 12.25; found: C 45.8, H 3.7, N 2.8, S 12.1.
Synthesis of 8: Compound 12[6a] (116 mg, 767 mmol) was added in a single
portion to a stirred solution of 16 (362 mg, 1.53 mmol) in acetonitrile
(5 mL) at 208C and the reaction mixture was stirred for 30 min at 208C
(evolution of hydrogen) and then allowed to stand at 208C for 3 d in the
absence of light. The resulting colorless crystalline solid was isolated by
filtration, washed with n-pentane (3ꢄ5 mL), and dried in vacuo
(0.01 mbar, 208C, 3 h; yield: 373 mg, 604 mmol, 79%). M.p. >1208C
(decomp.); 13C VACP/MAS NMR: d=47.0 (NCH3), 47.6 (NCH3), 119.6,
125.7, 126.6, 126.9, 127.3, 128.2, 129.4, 130.0, 131.6 (2C), 132.5, 139.5,
140.5 (2C), 141.5, 143.6, 145.8, and 146.0 ppm (SeC6H4Se, SiC6H4N); 15N
VACP/MAS NMR: d=ꢀ324.3 ppm; 29Si VACP/MAS NMR: d=
ꢀ107.9 ppm (with 77Se satellites);[17] 77Se VACP/MAS NMR: d=249.1,
285.1, 367.5, and 411.1 ppm; elemental analysis calcd (%) for
C20H19NSe4Si (Mr =617.30): C 38.91, H 3.10, N 2.27; found: C 39.0, H 3.1,
N 2.4.
Synthesis of 9: Compound 13[6b] (138 mg, 1.05 mmol) was added in a
single portion to a stirred solution of 14 (363 mg, 2.10 mmol) in dichloro-
methane (10 mL) at 208C and the reaction mixture was stirred for 15 min
at 208C (evolution of hydrogen) and then allowed to stand at 48C for 3 d
in the absence of light. The resulting colorless crystalline solid was isolat-
ed by filtration, washed with n-pentane (3ꢄ5 mL), and dried in vacuo
(0.01 mbar, 208C, 1 h; yield: 321 mg, 681 mmol, 65%). M.p. >1408C
(decomp.); 13C VACP/MAS NMR: d=53.0, 55.0, and 55.7 (SiCH2N,
NCH2C), 64.9 (2C) (OCH2C), 111.0, 114.7, 120.5, 121.3, 125.3 (2C),
127.4, 129.3 (2C), 133.2, 154.4, and 155.4 ppm (SeC6H4O); 15N VACP/
MAS NMR: d=ꢀ312.6 ppm; 29Si VACP/MAS NMR: d=ꢀ72.1 ppm
(with 77Se satellites);[17] 77Se VACP/MAS NMR: d=28.3, 60.7 ppm; ele-
mental analysis calcd (%) for C17H19NO3Se2Si (Mr =471.35): C 43.32, H
4.06, N 2.97; found: C 43.3, H 4.0, N 3.1.
(C-4/C-5, SeC6H4Se), 129.4 (C-3/C-6, SeC6H4Se), 141.3 ppm (C-1/C-2,
SeC6H4Se); 29Si NMR: d=ꢀ98.1 ppm (77Se satellites, 1J(29Si,77Se)=
109 Hz); 77Se NMR: d=243.3 ppm; 13C VACP/MAS NMR: d=54.3
(NCH2C), 56.2 (NCH2C), 61.8 and 62.2 (2C) (SiCH2N, OCH2C), 124.2,
125.4 (2C), 126.4, 127.9, 130.2, 131.0, 132.1, 139.4, 144.5, 144.9, and
145.6 ppm (SeC6H4Se); 15N VACP/MAS NMR: d=ꢀ308.5 ppm; 29Si
VACP/MAS NMR: d=ꢀ99.6 ppm (with 77Se satellites);[17] 77Se VACP/
MAS NMR: d=204.9, 264.8, 275.6, 299.9 ppm; elemental analysis calcd
(%) for C17H19NOSe4Si (Mr =597.27): C 34.19, H 3.21, N 2.35; found: C
33.8, H 3.2, N 2.5.
Synthesis of 14: 2-Bromophenol (4.33 g, 25.0 mmol) was added dropwise
over 15 min to a stirred mixture of a solution of sec-butyllithium (1.3m,
75.0 mmol) in cyclohexane/hexane (92:8; 57.7 mL), N,N,N’,N’-tetrame-
thylethane-1,2-diamine (5.81 g, 50.0 mmol), and n-hexane (30 mL) at
ꢀ408C and the reaction mixture was stirred for a further 30 min at
ꢀ408C. Subsequently, the reaction mixture was allowed to warm to 208C
over a period of 2 h and then stirred at this temperature for a further
30 min. The reaction mixture was cooled to 08C, then selenium powder
(1.97 g, 24.9 mmol) was added at this temperature in a single portion,
and the reaction mixture was allowed to warm to 208C over 30 min and
then stirred at this temperature for a further 24 h. The reaction mixture
was poured into cold (48C) hydrochloric acid (3m, 100 mL), the organic
layer was separated, the aqueous layer was extracted with n-pentane (5ꢄ
50 mL), and the combined organic extracts were dried over anhydrous
sodium sulfate. The solvents were removed by distillation under normal
pressure, and the residue was purified by fractional distillation in vacuo
to afford 14 as a colorless, oily liquid with an unpleasant odor (yield:
1
2.13 g, 12.3 mmol, 49%). B.p. 78–808C, 4 mbar; H NMR:[18] d=1.23–1.27
ACTHNUTRGNEUNG
(m, 77Se satellites, 1J(1H,77Se)=48 Hz, 1H; SeH), 6.06 (brs, 1H; OH),
6.79–6.87, 6.94–7.01, 7.21–7.30, and 7.53–7.60 ppm (m, 4H; SeC6H4O);
13C NMR: d=108.9 (C-2, SeC6H4O), 115.1 (C-6, SeC6H4O), 121.5 (C-4,
SeC6H4O), 131.1 (C-5, SeC6H4O), 137.4 (C-3, SeC6H4O), 156.6 ppm (C-1,
SeC6H4O); 77Se NMR: d=ꢀ24.0 ppm; elemental analysis calcd (%) for
C6H6OSe (Mr =173.07): C 41.64, H 3.49; found: C 41.9, H 3.8.
Synthesis of 15: A solution of n-butyllithium (2.5m, 122 mmol) in hex-
anes (48.9 mL) was added dropwise over 30 min to a stirred solution of
benzenethiol (6.14 g, 55.7 mmol) and N,N,N’,N’-tetramethylethane-1,2-di-
amine (7.12 g, 61.3 mmol) in n-hexane (100 mL) at 08C, and the resulting
mixture was stirred for a further 1 h. The reaction mixture was then al-
lowed to warm to 208C over 2 h and stirred at 208C for a further 3 d.
Subsequently, the mixture was cooled to 08C and selenium powder
(4.40 g, 55.7 mmol) was added in a single portion, and then the reaction
mixture was allowed to warm to 208C over 2 h and stirred for 2 d. The
mixture was poured into cold (48C) hydrochloric acid (3m, 160 mL), the
organic layer was separated, the aqueous layer was extracted with diethyl
ether (3ꢄ50 mL), and the combined organic extracts were dried over an-
hydrous sodium sulfate. The solvents were removed by distillation, and
the residue was purified by fractional distillation in vacuo to afford 15 as
a colorless, oily liquid with an unpleasant odor (yield: 6.82 g, 36.1 mmol,
65%). B.p. 98–1008C, 5 mbar; 1H NMR:[18] d=1.89–1.92 (m, 77Se satel-
ACTHNUTRGNEUNG
lites, 1J(1H,77Se)=55 Hz, 1H; SeH), 3.89–3.91 (m, 1H; SH), 6.98–7.06,
7.09–7.17, 7.34–7.41, and 7.48–7.55 ppm (m, 4H; SeC6H4S); 13C NMR:
d=127.2 (C-4, SeC6H4S), 127.6 (C-2, SeC6H4S), 127.9 (C-5, SeC6H4S),
131.1 (C-6, SeC6H4S), 133.7 (C-1, SeC6H4S), 134.4 ppm (C-3, SeC6H4S);
77Se NMR: d=134.8 ppm; elemental analysis calcd (%) for C6H6SSe
(Mr =189.14): C 38.10, H 3.20, S 16.95; found: C 38.5, H 3.3, S 16.8.
Synthesis of 10: Compound 13[6b] (134 mg, 1.02 mmol) was added in a
single portion to a stirred solution of 16 (482 mg, 2.04 mmol) in acetoni-
trile (15 mL) at 208C and the reaction mixture was stirred for 30 min at
208C (evolution of hydrogen and then allowed to stand at 208C for 4 d in
the absence of light. The resulting colorless crystalline solid was isolated
by filtration, washed with n-pentane (3ꢄ5 mL), and dried in vacuo
(0.01 mbar, 208C, 3 h; yield: 487 mg, 815 mmol, 80%). M.p. >1208C
(decomp.); 1H NMR:[18] d=3.10–3.20 (m, 2H; NCH2C), 3.29–3.36 (m,
Synthesis of 16: A solution of n-butyllithium (2.5m, 62.3 mmol) in hex-
anes (24.9 mL) was added dropwise within 20 min to a stirred solution of
benzeneselenol (4.44 g, 28.3 mmol) and N,N,N’,N’-tetramethylethane-1,2-
diamine (3.61 g, 31.1 mmol) in n-hexane (50 mL) at 08C, and the result-
ing mixture was stirred for a further 1 h at 08C. The reaction mixture was
then allowed to warm to 208C over 1 h and stirred for a further 20 h at
208C. The reaction mixture was cooled to 08C and selenium powder
(2.23 g, 28.2 mmol) was added in a single portion, and then the reaction
mixture was allowed to warm to 208C over 1 h and stirred at this temper-
ature for 4 d. The reaction mixture was poured into cold (48C) hydro-
chloric acid (3m, 80 mL), the organic layer was separated, the aqueous
layer was extracted with diethyl ether (3ꢄ60 mL), and the combined or-
ACTHNUTRGNEUNG
2H; NCH2C), 3.38 (d, 3J(1H,1H)=4.7 Hz, 2H; SiCH2N), 3.54–3.64 (m,
2H; OCH2C), 3.89–3.96 (m, 2H; OCH2C), 6.88–6.92 (m, 4H; H-4/H-5,
SeC6H4Se), 7.38–7.42 (m, 4H; H-3/H-6, SeC6H4Se), 9.0 ppm (brs, 1H;
NH); 13C NMR: d=55.7 (NCH2C), 61.3 (SiCH2N), 65.0 (OCH2C), 126.0
Chem. Eur. J. 2009, 15, 7329 – 7338
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7337

R. Tacke et al.
ganic extracts were dried over anhydrous sodium sulfate. The solvents
were removed by distillation at normal pressure, and the residue was pu-
rified by fractional distillation in vacuo to afford 16 as a colorless, oily
liquid with an unpleasant odor (yield: 3.64 g, 15.4 mmol, 54%). B.p. 94–
[4] a) R. Tacke, M. Mallak, R. Willeke, Angew. Chem. 2001, 113, 2401–
2403; Angew. Chem. Int. Ed. 2001, 40, 2339–2341; b) K. Naganuma,
T. Kawashima, J. Organomet. Chem. 2002, 643–644, 504–507; c) D.
Troegel, C. Burschka, S. Riedel, M. Kaupp, R. Tacke, Angew. Chem.
2007, 119, 7131–7135; Angew. Chem. Int. Ed. 2007, 46, 7001–7005,
and references therein; d) C.-W. So, H. W. Roesky, R. B. Oswald, A.
Pal, P. G. Jones, Dalton Trans. 2007, 5241–5244.
[5] Pentacoordination of silicon with a weak Si···Se interaction (Si···Se
3.1779(7) ꢃ) has been claimed (with the Se atom bound to two C
atoms), but the Si···Se distance is significantly longer than the sum
of covalent radii (2.34 ꢃ), and the 29Si chemical shift (d=ꢀ6.7 ppm)
also indicates only a weak Si···Se interaction; see: T. Saeki, A. Toshi-
mitsu, K. Tamao, Organometallics 2003, 22, 3299–3303.
[6] a) O. Seiler, M. Bꢁttner, M. Penka, R. Tacke, Organometallics 2005,
24, 6059–6062; b) R. Bertermann, A. Biller, M. Kaupp, M. Penka,
O. Seiler, R. Tacke, Organometallics 2003, 22, 4104–4110.
[7] A. Krief, L. Defrꢅre, Tetrahedron Lett. 1999, 40, 6571–6575.
[8] Data taken from: Holleman–Wiberg, Lehrbuch der Anorganischen
Chemie, 102nd ed., Walter de Gruyter, Berlin, 2007, p. 138.
[9] The Berry distortions were analyzed by using the PLATON program
system; A. L. Spek, PLATON, Utrecht University, Utrecht, The
Netherlands, 2008.
[10] U. Herzog, G. Rheinwald, Organometallics 2001, 20, 5369–5374.
[11] Because compound 3 reacts slowly with CD2Cl2 to give precursor 11
(almost quantitative transformation within 24 h), it was not possible
to increase the number of scans for the 29Si NMR measurement to
improve the signal-to-noise ratio.
ACTHNUTRGNEUNG
968C, 3 mbar; 1H NMR:[18] d=2.07–2.10 (m, 77Se satellites 1J(1H,77Se)=
54 Hz, 2H; SeH), 7.03–7.11 and 7.49–7.56 ppm (m, 4H; SeC6H4Se);
13C NMR: d=128.0 (C-4/C-5, SeC6H4Se), 129.9 (C-1/C-2, SeC6H4Se),
134.3 ppm (C-3/C-6, SeC6H4Se); 77Se NMR: d=160.2 ppm; elemental
analysis calcd (%) for C6H6Se2 (Mr =236.03): C 30.53, H 2.56; found: C
31.2, H 2.7.
Crystal structure analyses: Suitable single crystals of 1·CH3CN, 2·CH3CN,
3, and 5–10 were mounted in inert oil (perfluoropolyalkyl ether, ABCR)
on a glass fiber and then transferred to the cold nitrogen gas stream of
the diffractometer (Stoe IPDS (1·CH3CN, 5–8, and 10; graphite-mono-
chromated MoKa radiation, l=0.71073 ꢃ) or Bruker Nonius KAPPA
APEX II (2·CH3CN, 3, and 9; Montel mirror, MoKa radiation, l=
0.71073 ꢃ)). All structures were solved by direct methods (SHELXS-
97[19a]) and refined by full-matrix least-squares methods on F2 for all
unique reflections (SHELXL-97[19b]). For the CH hydrogen atoms, a
riding model was employed. CCDC-734846 (1·CH3CN), -734847
(2·CH3CN), -734848 (3), -734849 (5), -734850 (6), -734851 (7), -734852
(8), -734853 (9), and -734854 (10) contain the supplementary crystallo-
graphic data for this paper. These data can be obtained free of charge
from The Cambridge Crystallographic Data Centre via www.ccdc.cam.
ac.uk/data_request/cif.
[12] D. Seebach, A. K. Beck, Chem. Ber. 1975, 108, 314–321.
[13] K. Sasaki, Y. Aso, T. Otsubo, F. Ogura, Tetrahedron Lett. 1985, 26,
453–456.
[1] For selected reviews dealing with higher-coordinate silicon com-
pounds, see: a) R. R. Holmes, Chem. Rev. 1996, 96, 927–950; b) D.
Kost, I. Kalikhman in The Chemistry of Organic Silicon Compounds,
Vol. 2, Part 2 (Eds.: Z. Rappoport, Y. Apeloig), Wiley, New York,
1998, pp. 1339–1445; c) V. Pestunovich, S. Kirpichenko, M. Voron-
kov in The Chemistry of Organic Silicon Compounds, Vol. 2, Part 2
(Eds.: Z. Rappoport, Y. Apeloig), Wiley, New York, 1998, pp. 1447–
1537; d) C. Chuit, R. J. P. Corriu, C. Reye in Chemistry of Hyperva-
lent Compounds (Ed.: K.-y. Akiba), Wiley-VCH, Weinheim, 1999,
pp. 81–146; e) R. Tacke, M. Pꢁlm, B. Wagner, Adv. Organomet.
Chem. 1999, 44, 221–273; f) M. A. Brook, Silicon in Organic, Or-
ganometallic, and Polymer Chemistry, Wiley, New York, 2000,
pp. 97–114; g) R. Tacke, O. Seiler in Silicon Chemistry: From the
Atom to Extended Systems (Eds.: P. Jutzi, U. Schubert), Wiley-VCH,
Weinheim, 2003, pp. 324–337; h) D. Kost, I. Kalikhman, Adv. Orga-
nomet. Chem. 2004, 50, 1–106.
[14] Drying in vacuo over a longer period of time led to a partial loss of
acetonitrile.
1
[15] The reported H, 13C, and 29Si chemical shifts are those of the penta-
coordinate species.
[16] The accuracy of the elemental analysis is affected by the partial loss
of acetonitrile (even at storage at standard temperature and pres-
sure conditions).
[17] The solid-state 29Si NMR spectra of 6, 8, 9, and 10 show the exis-
tence of 1J(29Si,77Se) satellites in the range between 60–150 Hz. How-
ever, owing to overlapping satellites and satellites close to the main
29Si resonance signal, not all pairs of satellites expected from the re-
spective structures could be found.
[18] C1 is the atom bound to the XH group with the highest priority:
OH>SH>SeH.
[19] a) G. M. Sheldrick, SHELXS-97 Program for crystal structure solu-
tion, University of Gçttingen, Gçttingen, Germany, 1997; b) G. M.
Sheldrick, SHELXL-97 Program for crystal structure refinement,
University of Gçttingen, Gçttingen, Germany, 1997.
[2] For selected publications dealing with pentacoordinate silicon com-
ꢀ
ꢀ
pounds that contain Si Cl or Si Br bonds, see: a) A. R. Bassindale,
D. J. Parker, P. G. Taylor, N. Auner, B. Herrschaft, J. Organomet.
Chem. 2003, 667, 66–72; b) M. Driess, N. Muresan, K. Merz, Angew.
Chem. 2005, 117, 6896–6899; Angew. Chem. Int. Ed. 2005, 44, 6738–
6741; c) J. Wagler, Organometallics 2007, 26, 155–159; d) S. Metz, C.
Burschka, D. Platte, R. Tacke, Angew. Chem. 2007, 119, 7136–7139;
Angew. Chem. Int. Ed. 2007, 46, 7006–7009.
[3] H. H. Karsch, R. Richter, E. Witt, J. Organomet. Chem. 1996, 521,
185–190.
Received: March 5, 2009
Published online: July 3, 2009
7338
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ꢂ 2009 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
Chem. Eur. J. 2009, 15, 7329 – 7338