Neutral pentacoordinate halogeno- and pseudohalogenosilicon(iv) complexes with an sisoncx skeleton (x = f, cl, br, i, N, C): Synthesis and structural characterization in the solid state and in solution

Article abstract of DOI:10.1002/chem.201000152

A series of neutral pentacoordinate silicon(IV) complexes with an SiSONCX skeleton (X = F, Cl, Br, I, N, or C) was synthesized and structurally characterized by multinuclear solution-state and solid-state NMR spectroscopy and single-crystal X-ray diffraction. These compounds contain an identical tridentate dianionic S,N,O ligand, a monodentate (pseudo)halogeno ligand (F, Cl, Br, I, NCS, N₃, or CN), and a monodentate organyl ligand (methyl, phenyl, 4-(trifluoromethyl)phenyl, or pentafluorophenyl). For most of these compounds, a dynamic equilibrium between the pentacoordinate silicon(IV) complex and two isomeric tetracoordinate silicon species in solution was observed. Most surprisingly, comparison of two series of analogous compounds containing fluoro, chloro, bromo, or iodo ligands demonstrated that pentacoordination in these series of silicon(IV) complexes is favored in the rank order I≈Br> C1>F; i.e., increasing the softness of the halogeno ligand favors pentacoordination.

Full text of DOI:10.1002/chem.201000152

DOI: 10.1002/chem.201000152
Neutral Pentacoordinate Halogeno- and Pseudohalogenosilicon(IV)
Complexes with an SiSONCX Skeleton (X=F, Cl, Br, I, N, C): Synthesis and
Structural Characterization in the Solid State and in Solution
Stefan Metz, Bastian Theis, Christian Burschka, and Reinhold Tacke*[a]
Dedicated to Professor Hubert Schmidbaur on the occasion of his 75th birthday
Abstract: A series of neutral penta-
coordinate silicon(IV) complexes with
an SiSONCX skeleton (X=F, Cl, Br, I,
N, or C) was synthesized and structur-
ally characterized by multinuclear solu-
tion-state and solid-state NMR spec-
troscopy and single-crystal X-ray dif-
fraction. These compounds contain an
identical tridentate dianionic S,N,O
ligand, a monodentate (pseudo)halo-
geno ligand (F, Cl, Br, I, NCS, N3, or
CN), and
ligand (methyl, phenyl, 4-(trifluoro-
AHCTUNGTRENNmGUN ethyl)phenyl, or pentafluorophenyl).
For most of these compounds, a dy-
namic equilibrium between the penta-
coordinate silicon(IV) complex and
a
monodentate organyl
two isomeric tetracoordinate silicon
species in solution was observed. Most
surprisingly, comparison of two series
of analogous compounds containing
fluoro, chloro, bromo, or iodo ligands
demonstrated that pentacoordination
in these series of silicon(IV) complexes
is favored in the rank order IꢀBr>
Cl>F; i.e., increasing the softness of
the halogeno ligand favors pentacoor-
dination.
Keywords: halogens · pentacoordi-
nation · pseudohalogens · silicon ·
tridentate ligands
Introduction
Most of the penta- and hexacoordinate silicon(IV) com-
plexes reported in the literature contain hard ligand atoms,
such as fluorine, chlorine, oxygen, nitrogen, and/or
carbon.[1,2] In recent years, new perspectives for the chemis-
try of higher-coordinate silicon have been generated by in-
troducing soft chalcogen ligand atoms (sulfur, selenium, tel-
lurium) into the silicon(IV) coordination sphere.[2r,s,3] In this
context, the neutral pentacoordinate silicon(IV) complex 2
(SiSONCCl skeleton) has been synthesized and structurally
characterized both in the solid state and in solution.[3e] Com-
pound 2 is a versatile starting material for the synthesis of
other neutral pentacoordinate silicon(IV) complexes with
novel SiSONCX skeletons (X=O,[2r,3e] S,[2s] Se,[2s] Te,[2s] I[3e]).
For example, treatment of the chlorosilicon(IV) complex 2
with iodotrimethylsilane yields the corresponding iodosili-
AHCTUNGTRENNUNG
[a] Dr. S. Metz, Dr. B. Theis, Dr. C. Burschka, Prof. Dr. R. Tacke
Universitꢀt Wꢁrzburg
Institut fꢁr Anorganische Chemie
Am Hubland, 97074 Wꢁrzburg (Germany)
Fax : (+49)931-888-4609
E-mail: r.tacke@uni-wuerzburg.de
6844
ꢂ 2010 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
Chem. Eur. J. 2010, 16, 6844 – 6856

FULL PAPER
SONCCl skeletons), which are derivatives of 2 and 9 that
contain a 4-(trifluoromethyl)phenyl or pentafluorophenyl
moiety instead of the silicon-bound phenyl and methyl
group, respectively.
The aim of this study was to get information about the
impact of the halogeno/pseudohalogeno ligands of 1–7 and
8–11 on the structure of these compounds in the solid state
and in solution. In context with the structures in solution,
the potential equilibrium between these pentacoordinate sil-
icon(IV) complexes and their corresponding isomeric tetra-
coordinate species (see also reference [2s]) was of particular
interest. Furthermore, we made comparison of compounds
1–4 (SiPh group, electron-withdrawing) with their corre-
sponding analogues 8–11 (SiMe group, electron-donating) to
get information about the importance of the silicon-bound
organyl substituent of these compounds on the above-men-
tioned parameters. In this context, a comparison of the re-
lated compounds 2 (phenyl substituent), 12 (4-(trifluoro-
Scheme 2. Synthesis of compounds 8–11.
pared analogously to 1, 3, and 4, respectively, starting from
9.
A
Compounds 12 and 13 were obtained analogously to the
synthesis of 9 by treatment of trichloro[4-(trifluoromethyl)-
phenyl]silane (14) and trichloro(pentafluorophenyl)silane
(15), respectively, with one molar equivalent of 1-(2-methyl-
2,3-dihydrobenzothiazol-2-yl)propan-2-one and two molar
equivalents of triethylamine in tetrahydrofuran (Scheme 3).
great interest.
We report here on the synthesis of compounds 1, 3, and
5–13 and their structural characterization in the solid state
(crystal structure analysis, solid-state NMR spectroscopy)
and in solution (NMR spectroscopy). For reasons of com-
parison, compounds 2[3e] and 4[3e] were included in these
studies.
Results and Discussion
Syntheses: The fluorosilicon(IV) complex 1 was synthesized
by treatment of 2 with ammonium fluoride in tetrahydro-
ACHTUNGTRENNUNGfuran (Scheme 1). The related (pseudo)halogenosilicon(IV)
Scheme 3. Synthesis of compounds 12 and 13.
Compounds 1, 3, and 5–13 were isolated as yellow to
orange-colored crystalline solids (yields: 1, 57%; 3, 71%; 5,
86%; 6, 71%; 7, 61%; 8, 13% 9, 65%; 10, 68%; 11, 55%;
12, 65%; 13, 59%). Their identities were established by
using elemental analyses (C, H, N, S), multinuclear solution-
state and solid-state NMR spectroscopy, and single-crystal
X-ray diffraction.
Scheme 1. Synthesis of compounds 1, 3, and 5–7.
complexes 3 and 5–7 were obtained by reaction of 2 with
the corresponding (pseudo)halogenotrimethylsilane Me3SiX
(3, X=Br; 5, X=NCS; 6, X=N3; 7, X=CN) in acetonitrile.
The chlorosilicon(IV) complex 9 was obtained by treat-
Crystal structure analyses: Compounds 1, 3, and 5–13 were
structurally characterized by single-crystal X-ray diffraction.
The crystal data and the experimental parameters used for
the crystal structure analyses are given in Tables 1 and 2.
The molecular structures of 1, 3, and 5–13 in the crystal are
ment of trichloro
of 1-(2-methyl-2,3-dihydrobenzothiazol-2-yl)propan-2-one
and two molar equivalents of triethylamine in tetrahydro-
ACHTUNGTRENNUNGfuran (Scheme 2). The derivatives 8, 10, and 11 were pre-
ACHTUNGTRENNUNG(methyl)silane with one molar equivalent
Chem. Eur. J. 2010, 16, 6844 – 6856
ꢂ 2010 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
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6845

R. Tacke et al.
Table 1. Crystallographic data for compounds 1, 3, and 5–8.
1
3
5
6
7
8
empirical formula
C17H16FNOSSi
329.46
101(2)
C17H16BrNOSSi C18H16N2OS2Si
C17H16N4OSSi
352.49
193(2)
C18H16N2OSSi
336.48
193(2)
C12H14FNOSSi
267.39
173(2)
Mr [gmolꢁ1
T [K]
]
390.37
368.54
100(2)
193(2)
l
N
0.71073
monoclinic
P21/n (14)
7.7154(3)
15.0871(6)
13.6716(5)
97.699(2)
1577.07(10)
4
0.71073
monoclinic
P21/c (14)
10.8252(3)
8.6426(2)
17.4284(4)
96.076(2)
1621.40(7)
4
0.71073
monoclinic
P21/n (14)
11.4651(17)
12.7092(13)
12.4947(17)
90.558(17)
1820.5(4)
4
0.71073
0.71073
monoclinic
P21/n (14)
12.321(3)
10.077(2)
14.083(3)
105.27(3)
1686.7(6)
4
0.71073
crystal system
space group (no.)
monoclinic
P21/n (14)
10.9851(9)
9.8585(8)
15.2287(13)
91.742(10)
1648.5(2)
4
orthorhombic
P212121 (19)
8.5019(15)
9.9818(13)
15.248(2)
90
1294.1(3)
4
1.372
a [ꢀ]
b [ꢀ]
c [ꢀ]
b [8]
V [ꢃ3]
Z
1calcd [gcmꢁ3
m [mmꢁ1
(000)
1.388
0.292
688
1.599
2.738
792
1.345
0.365
768
1.420
0.281
736
1.325
0.268
704
0.338
560
F
crystal dimensions [mm]
2q range [8]
index ranges
0.34ꢄ0.29ꢄ0.21 0.22ꢄ0.13ꢄ0.11 0.4ꢄ0.4ꢄ0.4
0.5ꢄ0.5ꢄ0.5
4.92–56.22
ꢁ14ꢂhꢂ14,
ꢁ13ꢂkꢂ13,
ꢁ20ꢂlꢂ20
18696
0.4ꢄ0.3ꢄ0.2
5.30–58.10
ꢁ16ꢂhꢂ16,
ꢁ13ꢂkꢂ13,
ꢁ19ꢂlꢂ19
20593
0.5ꢄ0.5ꢄ0.4
4.88–58.14
ꢁ11ꢂhꢂ11,
ꢁ13ꢂkꢂ13,
ꢁ20ꢂlꢂ20
18671
4.04–72.48
ꢁ11ꢂhꢂ12,
ꢁ25ꢂkꢂ24,
ꢁ22ꢂlꢂ21
78402
3.78–56.64
ꢁ14ꢂhꢂ14,
ꢁ11ꢂkꢂ11,
ꢁ23ꢂlꢂ23
49475
5.78–56.08
ꢁ15ꢂhꢂ15,
ꢁ16ꢂkꢂ16,
ꢁ16ꢂlꢂ16
20657
reflns collected
independent reflns
Rint
7571
4043
4374
3951
0.0268
4431
0.0407
3444
0.0359
0.0581
0.0502
0.0494
parameters
201
1.091
0.0444/0.3882
0.0302
0.0900
201
1.052
0.0302/0.7958
0.0206
0.0575
219
1.047
0.0674/0.2605
0.0407
0.1119
219
1.039
0.0504/0.6042
0.0339
0.0915
210
1.061
0.0632/0.1056
0.0343
0.0984
157
1.074
0.0384/0.4512
0.0302
0.0770
S[a]
weight parameters a/b[b]
[c]
R1 [I>2s(I)]
wR2[d] (all data)
Flack parameter
ꢁ0.01(7)
max./min. residual electron density [eꢃꢁ3
]
+0.587/ꢁ0.290
+0.503/ꢁ0.304
+0.331/ꢁ0.508
+0.387/ꢁ0.402
+0.331/ꢁ0.199
+0.284/ꢁ0.227
2
2
2
[a] S={S[w
N
(nꢁp)}0.5; n=number of reflections; p=number of parameters. [b] wꢁ1 =s
A
(Fo ,0)+2Fc2]/3. [c] R1 =
2
SjjFo jꢁjFc jj/SjFo j. [d] wR2 ={S[w
(Fo )2]}0.5
ACHTUNGTERNNUNG .
Table 2. Crystallographic data for compounds 9–13.
9
10
11
12
13
empirical formula
C12H14ClNOSSi
283.84
100(2)
C12H14BrNOSSi
328.30
100(2)
C12H14INOSSi
375.29
193(2)
C18H15ClF3NOSSi
413.91
183(2)
C17H11ClF5NOSSi
435.87
173(2)
Mr [gmolꢁ1
T [K]
]
l
N
0.71073
0.71073
0.71073
monoclinic
P21/n (14)
11.067(2)
8.9631(18)
14.945(3)
99.94(3)
1460.2(5)
4
0.71073
0.71073
crystal system
space group (no.)
monoclinic
P21/n (14)
17.9248(8)
8.5692(3)
18.1280(8)
107.924(2)
2649.34(19)
8
monoclinic
P21/n (14)
18.1454(13)
8.6297(6)
18.1794(12)
108.843(4)
2694.1(3)
8
monoclinic
P21/n (14)
8.1896(10)
14.650(3)
14.984(2)
93.838(16)
1793.7(5)
4
orthorhombic
P212121 (19)
11.1904(10)
12.4881(17)
12.7298(12)
90
1778.9(3)
4
1.627
a [ꢀ]
b [ꢀ]
c [ꢀ]
b [8]
V [ꢃ3]
Z
1calcd [gcmꢁ3
m [mmꢁ1
(000)
1.423
0.519
1184
1.619
3.278
1328
1.707
2.403
736
1.533
0.433
848
0.457
880
F
crystal dimensions [mm]
2q range [8]
index ranges
0.13ꢄ0.07ꢄ0.03
2.80–62.64
ꢁ25ꢂhꢂ25,
ꢁ12ꢂkꢂ12,
ꢁ26ꢂlꢂ26
112870
0.3ꢄ0.3ꢄ0.1
3.86–56.98
ꢁ24ꢂhꢂ23,
ꢁ11ꢂkꢂ11,
ꢁ23ꢂlꢂ24
49700
0.5ꢄ0.4ꢄ0.2
5.32–58.16
ꢁ15ꢂhꢂ15,
ꢁ11ꢂkꢂ11,
ꢁ20ꢂlꢂ20
20260
0.4ꢄ0.3ꢄ0.3
5.56–58.18
ꢁ10ꢂhꢂ10,
ꢁ20ꢂkꢂ20,
ꢁ20ꢂlꢂ20
25507
0.4ꢄ0.4ꢄ0.3
4.56–58.12
ꢁ15ꢂhꢂ12,
ꢁ17ꢂkꢂ17,
ꢁ16ꢂlꢂ17
13702
reflns collected
independent reflns
Rint
8564
0.0559
6555
0.0477
3744
0.0342
4576
0.0322
4704
0.0508
parameters
313
1.033
0.0294/1.5730
0.0323
0.0781
314
1.071
0.0284/3.7850
0.0306
0.0758
157
1.096
0.0376/0.9388
0.0258
0.0681
237
1.110
0.0524/0.5376
0.0327
0.0927
246
1.067
0.0571/0.2612
0.0351
0.0949
S[a]
weight parameters a/b[b]
[c]
R1 [I>2s(I)]
wR2[d] (all data)
Flack parameter
0.00(6)
max./min. residual electron density [eꢃꢁ3
]
+0.442/ꢁ0.302
+0.644/ꢁ0.860
+0.452/ꢁ0.891
+0.406/ꢁ0.353
+0.350/ꢁ0.465
2
2
2
[a] S={S[w
N
(nꢁp)}0.5; n=number of reflections; p=number of parameters. [b] wꢁ1 =s
G
(Fo ,0)+2Fc2]/3. [c] R1 =
2
SjjFo jꢁjFc jj/SjFo j. [d] wR2 ={S[w
(Fo )2]}0.5
ACHTUNGTERNNUNG .
6846
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Chem. Eur. J. 2010, 16, 6844 – 6856

Pentacoordinate (Pseudo)halogenosilicon(IV) Complexes
FULL PAPER
Figure 1. Molecular structure of 1 in the crystal (probability level of dis-
ꢁ
placement ellipsoids 50%). Selected bond lengths [ꢃ] and angles [8]: Si
Figure 3. Molecular structure of 5 in the crystal (probability level of dis-
ꢁ
ꢁ
ꢁ
ꢁ
ꢁ
S
2.1712(3), Si F 1.6687(5), Si O 1.6967(6), Si N 2.0096(6), Si C1
placement ellipsoids 50%). Selected bond lengths [ꢃ] and angles [8]: Si
ꢁ
ꢁ
ꢁ
ꢁ
1.8745(7); S-Si-F 86.725(19), S-Si-O 123.28(2), S-Si-N 85.126(18), S-Si-C1
121.82(2), F-Si-O 87.59(3), F-Si-N 168.46(3), F-Si-C1 97.11(3), O-Si-N
90.06(3), O-Si-C1 114.89(3), N-Si-C1 94.13(3).
S1 2.1548(7), Si O 1.6788(13), Si N1 1.9684(13), Si N2 1.8729(17), Si
ꢁ
ꢁ
C1 1.8697(16), N2 C2 1.138(2), C2 S2 1.6082(18); S1-Si-O 128.49(5), S1-
Si-N1 86.48(4), S1-Si-N2 86.62(6), S1-Si-C1 116.66(6), O-Si-N1 91.90(6),
O-Si-N2 85.03(7), O-Si-C1 114.76(7), N1-Si-N2 168.30(7), N1-Si-C1
95.24(7), N2-Si-C1 96.31(8), Si-N2-C2 175.23(16), N2-C2-S2 178.33(17).
Figure 2. Molecular structure of 3 in the crystal (probability level of dis-
ꢁ
placement ellipsoids 50%). Selected bond lengths [ꢃ] and angles [8]: Si
ꢁ
ꢁ
ꢁ
ꢁ
Br 2.4051(4), Si S 2.1501(5), Si O 1.6802(10), Si N 1.9851(12), Si C1
1.8579(13); Br-Si-S 84.544(15), Br-Si-O 86.78(4), Br-Si-N 167.41(3), Br-Si-
C1 97.63(4), S-Si-O 127.61(4), S-Si-N 86.51(4), S-Si-C1 119.83(4), O-Si-N
91.71(5), O-Si-C1 112.51(5), N-Si-C1 94.50(5).
Figure 4. Molecular structure of 6 in the crystal (probability level of dis-
ꢁ
placement ellipsoids 50%). Selected bond lengths [ꢃ] and angles [8]: Si
ꢁ
ꢁ
ꢁ
ꢁ
S 2.1537(5), Si O 1.6768(10), Si N1 2.0071(12), Si N2 1.8573(14), Si C1
ꢁ
ꢁ
1.8507(14), N2 N3 1.134(2), N3 N4 1.137(3); S-Si-O 133.52(4), S-Si-N1
84.88(4), S-Si-N2 84.35(5), S-Si-C1 116.73(5), O-Si-N1 90.38(5), O-Si-N2
88.90(6), O-Si-C1 109.71(6), N1-Si-N2 164.41(6), N1-Si-C1 93.65(5), N2-
Si-C1 101.24(7), Si-N2-N3 128.66(12), N2-N3-N4 174.6(2).
shown in Figures 1–11; selected bond lengths and angles are
given in the respective figure legends.
The Si-coordination polyhedra of the neutral pentacoordi-
nate silicon(IV) complexes 1, 3, and 5–13 are similar to
those of 2 and 4 and are best described as distorted trigonal
bipyramids. The sulfur and oxygen atoms of the tridentate
S,N,O ligand and the carbon atom of the respective organyl
substituent occupy the equatorial positions, whereas the ni-
trogen atom of the tridentate S,N,O ligand and the (pseu-
do)halogeno ligand occupy the two axial positions. The axial
N-Si-X angles (X=F, Cl, Br, I, NCS, N3, CN) of 1–13 are in
ꢁ
Table 3. Comparison of the Si X (X=F, Cl, Br, I) bond lengths [ꢃ] of
1–4 and 8–11.
ꢁ
ꢁ
ꢁ
ꢁ
Compounds Si F
Si Cl
Si Br
Si I
2.7396(8)[a]
2.8225(7)
1–4
8–11
1.6687(5) 2.1954(4)[a]
1.6673(12) 2.2158(5),
2.2273(5)[b]
2.4051(4)
2.4291(8),
2.4469(8)[b]
[a] Ref. [3e]. [b] Molecules I and II.
Chem. Eur. J. 2010, 16, 6844 – 6856
ꢂ 2010 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
www.chemeurj.org
6847

R. Tacke et al.
Figure 5. Molecular structure of 7 in the crystal (probability level of dis-
ꢁ
placement ellipsoids 50%). Selected bond lengths [ꢃ] and angles [8]: Si
ꢁ
ꢁ
ꢁ
ꢁ
S 2.1834(6), Si O 1.6979(9), Si N1 1.9451(13), Si C1 1.8681(12), Si C2
ꢁ
1.9563(16), C2 N2 1.150(2); S-Si-O 138.61(4), S-Si-N1 84.96(3), S-Si-C1
114.48(4), S-Si-C2 84.24(4), O-Si-N1 91.43(5), O-Si-C1 106.87(5), O-Si-C2
87.01(5), N1-Si-C1 97.78(5), N1-Si-C2 161.73(5), C1-Si-C2 100.09(6), Si-
C2-N2 175.22(13).
Figure 7. Molecular structures of the two crystallographically independ-
ent molecules (Molecule I, above; Molecule II, below) in the crystal of 9
(probability level of displacement ellipsoids 50%). Selected bond lengths
ꢁ
ꢁ
[ꢃ] and angles [8] of Molecule I: Si1 Cl1 2.2158(5), Si1 S1 2.1756(5),
ꢁ
ꢁ
ꢁ
Si1 O1 1.6807(10), Si1 N1 1.9832(11), Si1 C1 1.8563(14); Cl1-Si1-S1
86.297(18), Cl1-Si1-O1 87.15(4), Cl1-Si1-N1 167.39(4), Cl1-Si1-C1
98.13(5), S1-Si1-O1 128.76(4), S1-Si1-N1 85.18(3), S1-Si1-C1 116.41(5),
O1-Si1-N1 90.96(5), O1-Si1-C1 114.83(6), N1-Si1-C1 93.99(5). Selected
Figure 6. Molecular structure of 8 in the crystal (probability level of dis-
ꢁ
placement ellipsoids 50%). Selected bond lengths [ꢃ] and angles [8]: Si
ꢁ
ꢁ
bond lengths [ꢃ] and angles [8] of Molecule II: Si2 Cl2 2.2273(5), Si2 S2
ꢁ
ꢁ
ꢁ
ꢁ
S 2.1816(6), Si F 1.6673(12), Si O 1.6987(13), Si N 2.0069(13), Si C1
1.8620(18); S-Si-F 87.64(5), S-Si-O 125.73(6), S-Si-N 84.89(4), S-Si-C1
117.76(6), F-Si-O 87.35(6), F-Si-N 168.97(6), F-Si-C1 98.69(8), O-Si-N
90.43(6), O-Si-C1 116.42(8), N-Si-C1 91.98(7).
ꢁ
ꢁ
ꢁ
2.1680(5), Si2 O2 1.6736(10), Si2 N2 1.9798(12), Si2 C21 1.8533(14);
Cl2-Si2-S2 86.499(18), Cl2-Si2-O2 87.06(4), Cl2-Si2-N2 168.54(4), Cl2-
Si2-C21 98.37(5), S2-Si2-O2 126.08(4), S2-Si2-N2 85.22(4), S2-Si2-C21
119.02(5), O2-Si2-N2 91.43(5), O2-Si2-C21 114.89(6), N2-Si2-C21
92.57(6).
the range 161.73(5)–171.56(6)8, and the sum of the equatori-
al bond angles is between 359.1 and 360.08.
coordinate iodosilicon(IV) complexes that have been struc-
ꢁ
The Si X (X=F, Cl, Br, I) bond lengths of the halogeno-
turally characterized by single-crystal X-ray diffraction. The
[3e]
ꢁ
silicon(IV) complexes 1–4 and 8–11 are given in Table 3. As
can be seen from these data, replacement of the SiPh group
of 1–4 by an SiMe moiety (! 8–11) leads to a small elonga-
Si I distances of 4 and 11 are significantly longer than the
ꢁ
Si I bond lengths of tetracoordinate silicon compounds
[5]
ꢁ
(e.g., Si I 2.4339(19)–2.5720(13) ꢃ).
ꢁ
ꢁ
tion of the respective Si X bonds, except for the SiPh/SiMe
pair 1/8 for which almost identical Si F distances were ob-
served. There are only a few reports on pentacoordinate sili-
con species with Si Br bonds, and the Si Br distances of 3
The Si E (E=S, O, N, C) bond lengths of the homolo-
ꢁ
gous series of the halogenosilicon(IV) complexes 1–4 and 8–
11 are listed in Table 4. As can be seen from these data, the
Si–E distances in both series of compounds are affected by
ꢁ
ꢁ
ꢁ
ꢁ
and 10 are in the range of the reported axial Si Br bond
the nature of the halogeno ligand: The longer the Si X
lengths.[2o,4] Compounds 4[3e] and 11 represent the first penta-
bond (X=F, Cl, Br, I), the shorter are the analogous Si E
ꢁ
6848
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Chem. Eur. J. 2010, 16, 6844 – 6856

Pentacoordinate (Pseudo)halogenosilicon(IV) Complexes
FULL PAPER
Figure 9. Molecular structure of 11 in the crystal (probability level of dis-
ꢁ
placement ellipsoids 50%). Selected bond lengths [ꢃ] and angles [8]: Si
ꢁ
ꢁ
ꢁ
ꢁ
I 2.8225(7), Si S 2.1338(8), Si O 1.6733(16), Si N 1.9312(17), Si C1
1.858(2); I-Si-S 83.28(3), I-Si-O 83.70(6), I-Si-N 169.19(5), I-Si-C1
93.77(7), S-Si-O 121.95(6), S-Si-N 89.39(6), S-Si-C1 121.18(8), O-Si-N
93.54(8), O-Si-C1 115.96(10), N-Si-C1 96.83(9).
Figure 8. Molecular structures of the two crystallographically independ-
ent molecules (Molecule I, above; Molecule II, below) in the crystal of 10
(probability level of displacement ellipsoids 50%). Selected bond lengths
ꢁ
ꢁ
[ꢃ] and angles [8] of Molecule I: Si1 Br1 2.4291(8), Si1 S1 2.1657(10),
ꢁ
ꢁ
ꢁ
Si1 O1 1.679(2), Si1 N1 1.958(3), Si1 C1 1.857(3); Br1-Si1-S1 85.37(3),
Br1-Si1-O1 85.98(8), Br1-Si1-N1 167.31(8), Br1-Si1-C1 96.85(10), S1-Si1-
O1 128.20(9), S1-Si1-N1 86.15(8), S1-Si1-C1 116.86(10), O1-Si1-N1
91.89(10), O1-Si1-C1 114.85(12), N1-Si1-C1 95.40(12). Selected bond
Figure 10. Molecular structure of 12 in the crystal (probability level of
displacement ellipsoids 50%). Selected bond lengths [ꢃ] and angles [8]:
ꢁ
ꢁ
ꢁ
ꢁ
ꢁ
Si Cl 2.2413(6), Si S 2.1359(6), Si O 1.6728(11), Si N 2.0022(12), Si C1
1.8780(14); Cl-Si-S 85.33(2), Cl-Si-O 87.28(4), Cl-Si-N 170.10(4), Cl-Si-C1
95.86(4), S-Si-O 126.96(4), S-Si-N 87.11(4), S-Si-C1 121.11(5), O-Si-N
92.17(5), O-Si-C1 111.88(6), N-Si-C1 93.52(5).
ꢁ
ꢁ
lengths [ꢃ] and angles [8] of Molecule II: Si2 Br2 2.4469(8), Si2 S2
ꢁ
ꢁ
ꢁ
2.1623(11), Si2 O2 1.672(2), Si2 N2 1.953(3), Si2 C21 1.850(3); Br2-Si2-
S2 85.70(3), Br2-Si2-O2 85.55(8), Br2-Si2-N2 168.34(8), Br2-Si2-C21
97.15(10), S2-Si2-O2 125.96(9), S2-Si2-N2 86.12(8), S2-Si2-C21
119.07(10), O2-Si2-N2 92.56(10), O2-Si2-C21 114.91(13), N2-Si2-C21
94.08(12).
ꢁ
ꢁ
The Si N2 distance (1.8729(17) ꢃ) of the Si NCS moiety
of 5 and the almost linear Si-N2-C2 (175.23(16)8) and N2-
C2-S2 angles (178.33(17)8) are similar to the respective
structural data of other neutral pentacoordinate silicon(IV)
complexes with axial thiocyanato-N ligands, but to some
extent also differs from previously reported data.[6] To the
best of our knowledge, compound 6 is the first neutral pen-
tacoordinate silicon(IV) complex with an azido ligand that
could be structurally characterized by using single-crystal X-
ray diffraction. Therefore, the structural features of the
bonds, with maximum bond length differences of 0.045/
ꢁ
ꢁ
0.048 ꢃ (Si S bonds), 0.031/0.025 ꢃ (Si O), 0.074/0.076 ꢃ
ꢁ
ꢁ
(Si N), and 0.024/0.009 ꢃ (Si C), respectively.
ꢁ
The respective Si E (E=S, O, N, C) bond lengths of the
pseudohalogenosilicon(IV) complexes 5 (X=NCS) and 6
(X=N3) are very similar and fit best with those of the relat-
ed halogenosilicon(IV) complexes 2 (X=Cl) and 3 (X=Br).
In contrast, compound 7 (X=CN) with its longer Si S
(2.1834(6) ꢃ) and shorter Si N bond (1.9451(13) ꢃ) differs
ꢁ
ꢁ
ꢁ
Si N3 moiety of 6 can only be compared with those of
from its derivatives 2, 3, 5, and 6.
the
hexa
coordinate
dianionic
silicon(IV)
complex
Chem. Eur. J. 2010, 16, 6844 – 6856
ꢂ 2010 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
www.chemeurj.org
6849

R. Tacke et al.
ꢁ
Table 5. Comparison of the Si E (E=Cl, S, O, N, C) bond lengths [ꢃ] of
2, 12, and 13.
ꢁ
ꢁ
ꢁ
ꢁ
ꢁ
Compound Si Cl
Si S
Si O
Si N
Si C
2[a]
12
13
2.1954(4) 2.1571(4) 1.6850(8)
2.2413(6) 2.1359(6) 1.6728(11) 2.0022(12) 1.8780(14)
2.2288(7) 2.1251(7) 1.7056(14) 1.9374(17) 1.912(2)
2.0069(10) 1.8593(11)
[a] Reference [3e].
ꢁ
significantly longer than the Si C2 bond length of 7
ꢁ
(1.9563(16) ꢃ), whereas the C2 N2 bond length
(1.150(2) ꢃ) and the Si-C2-N2 angle (175.22(13)8) of 7 are
very similar to the respective data of the reference com-
pound (1.144(8) ꢃ, 175.1(4)8).
As can be seen in Table 5, replacement of the phenyl
group of 2 by the more electron-withdrawing 4-(trifluoro-
A
Figure 11. Molecular structure of 13 in the crystal (probability level of
displacement ellipsoids 50%). Selected bond lengths [ꢃ] and angles [8]:
ꢁ
ꢁ
leads to different effects: In the case of the Si Cl and Si C
bonds, an increase in bond lengths was observed, whereas
the Si S and Si N bond lengths are shortened. In the case
of the Si O bond lengths, a decrease (12) and an increase
ꢁ
ꢁ
ꢁ
ꢁ
ꢁ
Si Cl 2.2288(7), Si S 2.1251(7), Si O 1.7056(14), Si N 1.9374(17), Si C1
1.912(2); Cl-Si-S 86.22(3), Cl-Si-O 88.13(6), Cl-Si-N 171.56(6), Cl-Si-C1
94.88(6), S-Si-O 132.39(6), S-Si-N 89.16(5), S-Si-C1 117.35(6), O-Si-N
89.77(7), O-Si-C1 110.23(8), N-Si-C1 93.52(8).
(13), respectively, was observed. These effects are not fully
understood so far.
ꢁ
Table 4. Comparison of the Si E (E=S, O, N, C) bond lengths [ꢃ] of 1–
4 and 8–11 and maximum bond length differences Dmax [ꢃ].
NMR studies: Compounds 1, 3, and 5–13 were characterized
by using multinuclear solution-state and solid-state NMR
spectroscopy. The NMR-spectroscopic data obtained (see
the Experimental Section) are in accordance with the exper-
imentally established crystal structures of these compounds.
Analysis of Table 6 reveals that the isotropic 15N and 29Si
chemical shifts of 1–13 in the solid state strongly depend on
the nature of both the (pseudo)halogeno ligand (compounds
ꢁ
ꢁ
ꢁ
ꢁ
Compound
and Dmax
Si S
Si O
Si N
Si C
1 (X=F)
2 (X=Cl)[a]
3 (X=Br)
4 (X=I)[a]
Dmax
2.1712(3)
2.1571(4)
2.1501(5)
2.1262(10)
0.045
2.1816(6)
2.1756(5),
2.1680(5)
2.1657(10),
2.1623(11)
2.1338(8)
0.048
1.6967(6)
1.6850(8)
1.6802(10)
1.6655(19)
0.031
1.6987(13)
1.6807(10),
1.6736(10)
1.679(2),
1.672(2)
2.0096(6)
2.0069(10)
1.9851(12)
1.936(2)
1.8745(7)
1.8593(11)
1.8579(13)
1.851(3)
0.024
1.8620(18)
1.8563(14),
1.8533(14)
1.857(3),
1.850(3)
1.858(2)
0.009
0.074
8 (X=F)
9 (X=Cl)[b]
2.0069(13)
1.9832(11),
1.9798(12)
1.958(3),
1.953(3)
10 (X=Br)[b]
Table 6. Isotropic 15N and 29Si chemical shifts of compounds 1–13 in the
solid state.
11 (X=I)
Dmax
1.6733(16)
0.025
1.9312(17)
0.076
Compound
d15N[a] [ppm]
d29Si [ppm]
[a] Reference [3e]. [b] Molecules I and II.
1 (X=F)
ꢁ151.5
ꢁ89.1
ꢁ83[c]
ꢁ89[c]
ꢁ91[c]
ꢁ98.8
ꢁ87.1
ꢁ100.8
ꢁ77.7
ꢁ75[c]
ꢁ80[c]
ꢁ72[c]
ꢁ84[c]
ꢁ93[c]
2 (X=Cl)[b]
3 (X=Br)
4 (X=I)[b]
5 (X=NCS)
6 (X=N3)
7 (X=CN)
8 (X=F)
ꢁ149.4
ꢁ153.6
[(Ph3P)2N]2[Si(N3)6].[7] The Si N bond lengths of the
[Si(N3)6]2ꢁ dianion (1.866(1)–1.881(1) ꢃ) are somewhat
ꢁ
ꢁ163.8
ꢁ157.6
ꢁ145.4 or ꢁ140.4[d]
ꢁ158.8
ꢁ
longer than the Si N2 bond lengths of 6 (1.8573(14) ꢃ).
ꢁ
However, the major difference of the Si N3 moieties of 6
ꢁ147.9
and the [Si(N3)6]2ꢁ dianion concerns the N N bond lengths
ꢁ
9 (X=Cl)
10 (X=Br)
11 (X=I)
12 (X=Cl)
13 (X=Cl)
ꢁ152.4
ꢁ160.2
of the azido ligand. In principle, two mesomeric structures
ꢁ169.0
ꢁ
ꢁ
ꢁ
of the Si N3 group are possible, Si Na=Nb=Ng (A) and Si
ꢁ152.1
ꢁ
ꢃ
ꢁ
Na Nb Ng (B). In the case of 6, the very similar N2 N3
ꢁ171.1
ꢁ
(1.134(2) ꢃ) and N3 N4 distance (1.137(3) ꢃ) indicate the
dominance of the mesomeric structure A. In contrast, the
[a] Nitrogen atom of the tridentate S,N,O ligand. [b] Reference [3e].
[c] Broad resonance signal. [d] For details, see the Experimental Section.
ꢁ
strong differentiation between the Na Nb (1.198(2)–
ꢁ
1.207(2) ꢃ) and Nb Ng distance (1.144(2)–1.146(2) ꢃ) of the
[Si(N3)6]2ꢁ dianion reflect an increased dominance of the
1–7; F, Cl, Br, I, NCS, N3, CN) and the organyl ligand (com-
parison of 1–4 with 8–11, Ph/Me exchange; comparison of 2
with
ꢁ
mesomeric structure B. The structural features of the Si CN
moiety of 7 can only be compared with one neutral penta-
12
and
13,
phenyl/4-(trifluoromethyl)phenyl/
coordinate (cyano-N)silicon(IV) complex that has been
pentafluoroCATHNUGTRNEUNG
phenyl exchange). The 15N chemical shifts are in
studied by crystal structure analysis.[8] The Si CN bond
the range d=ꢁ147.9 to ꢁ171.1 ppm, and the 29Si chemical
shifts range from d=ꢁ72 to ꢁ100.8 ppm. As shown exem-
ꢁ
length (2.050(6) ꢃ) of this trigonal-bipyramidal compound is
6850
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Chem. Eur. J. 2010, 16, 6844 – 6856

Pentacoordinate (Pseudo)halogenosilicon(IV) Complexes
FULL PAPER
of 1–13 in the solid state and in
solution are identical; that is,
the oxygen and sulfur atom of
this ligand occupy equatorial
positions of a distorted trigonal
bipyramid, whereas the nitro-
gen atom occupies an axial po-
sition. This assumption is based
1
on a comparison of the H and
13C NMR data of 1–13 with
those of compounds 16–18,[2s]
for which a totally different co-
ordination mode is observed: In
the case of 16–18, the oxygen
and sulfur atom of the triden-
tate ligand occupy the two axial
1
positions. The H and 13C NMR
data of the tridentate ligand
allow for differentiation be-
tween these two different coor-
dination modes.
Figure 12. Partial 29Si VACP/MAS spectra of A) 8 (X=F), B) 9 (X=Cl), C) 10 (X=Br), and D) 11 (X=I).
MAS frequencies: A) 7000 Hz, B) 6000 Hz, C) 6500 Hz, and D) 6500 Hz. Spinning side bands have been omit-
ted for clarity.
Additional solution-state 29Si
NMR experiments with 1–13,
plarily for 9 (X=Cl), 10 (X=Br), and 11 (X=I) in
Figure 12, the 29Si VACP/MAS NMR spectra of all com-
pounds that contain chloro, bromo, or iodo ligand atoms
show broad and structured resonance signals. This phenom-
enon can be explained by 29Si,X
couplings (X=35Cl (I=3/2),
37Cl (I=3/2); 79Br (I=3/2), 81Br
Table 7. Solution-state 29Si NMR data of compounds 1–13.
(I=3/2); 127I (I=5/2)) and the
Compound
d
29Si (A) [ppm]
d
29Si (B)[a] [ppm]
Molar ratio A:B[b]
Solvent
well-known effect that MAS
fails to completely eliminate
the effect of dipolar coupling
for spin 1/2 when coupled to
quadrupole nuclei with a quad-
rupole frequency comparable to
the Zeeman frequency of the
nuclei.[9] As also shown exem-
plarily for 8 in Figure 12, a
29Si,19F coupling was observed
for the two fluorosilicon(IV)
complexes 1 and 8.
1 (X=F)
ꢁ88.1[c]
ꢁ88.1[c]
ꢁ81.2
ꢁ82.3
ꢁ86.7
ꢁ92.5
ꢁ98.3
ꢁ87.8
ꢁ86.5
ꢁ99.9
ꢁ74.1[c]
ꢁ74.8[c]
ꢁ73.3[c]
ꢁ71.4
ꢁ72.5
ꢁ70.4
ꢁ75.8
ꢁ75.6
ꢁ83.4
ꢁ84.3
ꢁ82.4
ꢁ92[f]
ꢁ53.69,[c] ꢁ53.68[c]
ꢁ53.6,[c] ꢁ53.4[c]
ꢁ33.2, ꢁ32.8
70:30
80:20
88:12
CD2Cl2
CD3CN
CD2Cl2
CD3CN
CD2Cl2
CD2Cl2
CD2Cl2
CD2Cl2
C6D6
CD2Cl2
CD2Cl2
CD3CN
C6D6
CD2Cl2
CD3CN
C6D6
CD2Cl2
CD2Cl2
CD2Cl2
CD3CN
C6D6
2 (X=Cl)
[d]
–
95:5
3 (X=Br)
4 (X=I)
5 (X=NCS)
6 (X=N3)
–
–
–
100:0[e]
100:0[e]
100:0[e]
90:10
ꢁ47.3, ꢁ47.1
ꢁ47.0, ꢁ46.4
–
70:30
7 (X=CN)
8 (X=F)
100:0[e]
30:70
ꢁ37.32,[c] ꢁ37.26[c]
ꢁ36.8,[c] ꢁ36.7[c]
ꢁ37.6,[c] ꢁ37.2[c]
ꢁ19.2
45:55
8:92
80:20
90:10
9 (X=Cl)
The 29Si chemical shifts of 1–
13 determined by solution-state
NMR experiments (solvent,
CD2Cl2; Table 7) are very simi-
lar to those obtained in the
solid state and indicate that the
ꢁ19.3, ꢁ19.0
ꢁ19.7, ꢁ19.1
–
50:50
10 (X=Br)
11 (X=I)
12 (X=Cl)
100:0[e]
100:0[e]
93:7
–
–
[d]
–
100:0[e]
83:17
ꢁ34.1, ꢁ33.4
13 (X=Cl)
–
–
–
100:0[e]
100:0[e]
100:0[e]
CD2Cl2
CD3CN
C6D6
pentacoordinate
silicon(IV)
ꢁ93[f]
complexes 1–13 also exist in so-
ꢁ91[f]
1
lution. According to the H and
[a] Data for two diastereomers. [b] Ratio determined by 1H NMR spectroscopy. [c] The 29Si NMR resonance
13C NMR data of the tridentate
signal is a doublet owing to 1J
NMR shift. [e] The existence of traces (<1%) of B can not be totally ruled out. [f] The 29Si NMR resonance
(29Si,19F) couplings.
(Si,F) coupling. [d] The concentration of B was too low to determine the 29Si
ACHTUNGTRENNUNG
O,N,S ligand it is likely to
assume that the configurations signal is a multiplet owing to J
ACHTUNGTRENNUNG
Chem. Eur. J. 2010, 16, 6844 – 6856
ꢂ 2010 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
www.chemeurj.org
6851

R. Tacke et al.
Scheme 4. Dynamic equilibrium of 1–13 between penta- (A) and tetra-
coordination (B) in solution.
using CD2Cl2, CD3CN, and C6D6 as the solvent, revealed, in
most cases, the existence of a dynamic equilibrium between
the pentacoordinate species A and the tetracoordinate spe-
Figure 14. 19F NMR spectra of 8 in A) CD3CN, B) CD2Cl2, and C) C6D6
(left: resonance signal of the pentacoordinate species A; right: resonance
signals of the two diastereomeric tetracoordinate species B).
cies
B (existing as two diastereomers), as shown in
Scheme 4. The results of these studies are summarized in
Table 7. The identities of the tetracoordinate species of the
mental detection limits, exclusively pentacoordination was
observed (solvent: CD3CN, CD2Cl2, C6D6), whereas tetra-
coordination is favored in the case of 8 (ratio A/B: 45:55
(CD3CN), 30:70 (CD2Cl2), 8:92 (C6D6); Figure 14).
Unfortunately, the poor solubility of some of these sili-
AHCTUNGTREGNNcNU on(IV) complexes in CD3CN and C6D6 did not allow a sys-
tematic study of the solvent dependent A/B ratio for all
compounds, but it appears that pentacoordination is favored
in the rank order CD3CN>CD2Cl2 >C6D6; i.e., the more
polar the solvent, the more stable is the pentacoordinate sili-
con(IV) A complex compared to the corresponding tetra-
coordinate species B.
1
formula type B were established by using H, 13C, and 29Si
NMR studies (data not given); the NMR data of these spe-
cies are very similar to those reported for the two diastereo-
mers of B with X=OPh (one of these diastereomers has
been additionally characterized by single-crystal X-ray dif-
fraction).[2s]
The existence of a dynamic equilibrium could be demon-
strated qualitatively by 2D EXSY NMR studies (exchange
spectroscopy). This method indicates multisite chemical ex-
change by cross signals for all exchanging species. As can be
seen exemplarily for compound 9 from Figure 13, the SiCH3
As can be seen from Table 7, the nature of the halogeno
ligand of the silicon(IV) complexes 1–4 and 8–11 significant-
ly affects the A/B ratio. In both series of compounds, the
halogeno ligands favor pentacoordination in the following
order: IꢀBr>Cl>F; i.e., the more electronegative (hard)
the halogeno ligand, the lower is the stability of the penta-
coordinate silicon(IV) complex A compared to the corre-
sponding tetracoordinate species B. Replacement of the
electron-withdrawing phenyl group of 1–4 by an electron-
donating methyl moiety (! 8–11) leads to a destabilization
of pentacoordination, and exchange of the phenyl group of
2 by the more electron-withdrawing 4-(trifluoromethyl)-
phenyl (! 12) and pentafluorophenyl group (! 13), respec-
tively, leads to a stabilization of pentacoordination. These
effects of the organyl ligands are expected, whereas the
effect of the halogeno ligands is not understood, if it is as-
sumed that hard ligand atoms should favor pentacoordina-
tion of the hard silicon(IV) coordination center (F>Cl>
Br>I). To fully understand the effect of the different mono-
dentate ligands on the A/B ratio, information on their effect
on the stability of the tetracoordinate species B is also nec-
essary.
1
Figure 13. Partial H,1H EXSY NMR spectrum of 9 in CD2Cl2 (A, SiCH3
resonance signal of the pentacoordinate species; B, SiCH3 resonance sig-
nals of the two diastereomeric tetracoordinate species).
group of the pentacoordinate species A is in direct exchange
with the SiCH3 groups of the two diastereomeric tetracoor-
dinate species B; furthermore, an exchange between the two
isomeric species B can be observed.
According to these studies, the molar ratio A/B is affected
by the (pseudo)halogeno ligand, the organyl ligand, and the
solvent. For example, in the case of 13, within the experi-
Conclusion
In this study, we have demonstrated that the pentacoordi-
nate chlorosilicon(IV) complex 2 and its derivative 9 (Ph/
Me exchange) are versatile precursors for the synthesis of
related pentacoordinate silicon compounds that contain
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Chem. Eur. J. 2010, 16, 6844 – 6856

Pentacoordinate (Pseudo)halogenosilicon(IV) Complexes
FULL PAPER
dard, TMS (13C, 29Si; d=0 ppm) or glycine (15N, d=ꢁ342.0 ppm); spin-
ning rate, 5–7 kHz; contact time, 1 ms (13C), 3 ms (15N), or 5 ms (29Si); 908
1H transmitter pulse length, 3.6 ms; repetition time, 4 s).
other halogeno (F, Br, I) or pseudohalogeno ligands (NCS,
N3, CN) instead of the chloro ligand. With the synthesis of
9, 12, and 13, we have also demonstrated that derivatives of
2 with other organyl ligands instead of the phenyl group can
be prepared. These compounds are expected to be versatile
precursors for the synthesis of related pentacoordinate sili-
con(IV) complexes with other halogeno and pseudohaloge-
no ligands. In this context, compound 13 with its strongly
electron-withdrawing pentafluorophenyl group is particular-
ly promising.
Notably, the pentacoordinate halogenosilicon(IV) com-
plexes 1–4 and 8–13 each contain five different ligand atoms
in the silicon coordination sphere; all these compounds con-
tain an SiSONCX skeleton (X=F, Cl, Br, I). The existence
of 3, 4, 10, and 11 with their bromo and iodo ligand, respec-
tively, is particularly remarkable.
Syntheses of 2 and 4: Compounds 2 and 4 were synthesized according to
reference [3e].
Synthesis of 1: Ammonium fluoride (107 mg, 2.89 mmol) was added in a
single portion at 208C to a stirred solution of 2 (1.00 g, 2.89 mmol) in tet-
rahydrofuran (15 mL), and the reaction mixture was then stirred at 208C
for 24 h. The resulting solid was filtered off, washed with tetrahydrofuran
(5 mL), and discarded. The solvent of the filtrate (including the wash so-
lution) was removed in vacuo, and the residue was dissolved in toluene
(3 mL). The resulting solution was slowly concentrated in vacuo, until the
formation of a solid started. Toluene (1 mL) was added, and the mixture
was heated until a clear solution was obtained, which was kept undisturb-
ed at 208C for 20 h and then at ꢁ208C for a further 24 h. The resulting
precipitate was filtered off, washed with n-pentane (5 mL), and dried in
vacuo (0.01 mbar, 208C, 2 h) to give 1 in 57% yield (548 mg, 1.66 mmol)
as a yellow crystalline solid. M.p. >1108C (decomp); 1H NMR (CD3CN,
ACTHNUTRGNEUNG
300.1 MHz):[10] d=2.12 (d, 4J(1H,1H)=0.5 Hz, 3H; CCH3), 2.36 (s, 3H;
CCH3), 5.83–5.85 (m, 1H; CCHC), 6.97–7.03, 7.04–7.10, 7.18–7.28, 7.33–
7.37, 7.48–7.51 ppm (m, 9H; SC6H4N, SiC6H5); 13C NMR (CD3CN,
75.5 MHz): d=24.0 (CCH3), 24.3 (CCH3), 105.0 (CCHC), 124.7, 124.9,
Compounds 1–13 exist both in the solid state and in solu-
tion. They all contain a distorted trigonal-bipyramidal Si-co-
ordination polyhedron, with the oxygen and sulfur atom of
the tridentate S,N,O ligand in equatorial positions, whereas
the nitrogen atom occupies an axial site.
Solution-state NMR studies of 1–13 revealed, in most
cases, the existence of a dynamic equilibrium between these
pentacoordinate silicon(IV) complexes (A) and two isomer-
ic tetracoordinate species (B). The A/B ratio depends on
the nature of the (pseudo)halogeno and organyl ligands and
on the solvent. These effects are not yet fully understood.
Most surprisingly, in the two series of the halogenosili-
128.5 (d,
ACTHNGUTRENNUG ACHTUNGTRENNUNG
(13C,19F)=3.6 Hz, 2 C), 133.7 (d, J(13C,19F)=8.7 Hz), 138.0 (d, J(13C,19F)=
JACTHNGUTERNNUG
(13C,19F)=4.4 Hz), 128.6 (2 C), 128.8, 130.9, 133.5 (d, J-
A
26 Hz), 138.9 (SC6H4N, SiC6H5), 171.8 (JACTHNUTRGNEUNG
(13C,19F)=8.0 Hz, CN or CO),
173.0 ppm (CN or CO); 19F NMR (CD3CN, 376.5 MHz): d=ꢁ83.2 ppm;
29Si NMR (CD3CN, 59.6 MHz): d=ꢁ88.1 ppm (d, 1J
(29Si,19F)=261 Hz);
ACHTUNGTRENNUNG
13C VACP/MAS NMR: d=22.3 (CCH3), 24.8 (CCH3), 105.1 (CCHC),
124.7, 125.6 (2 C), 128.0 (2 C), 130.0 (3 C), 131.5, 133.0, 135.7, 137.9
(SC6H4N, SiC6H5), 170.3 (CN or CO), 171.9 ppm (CN or CO); 15N
VACP/MAS NMR: d=ꢁ151.5 ppm; 29Si VACP/MAS NMR: d=
ꢁ89.1 ppm (d, 1J
(29Si,19F)=266 Hz); elemental analysis calcd (%) for
ACHTUNGTRENNUNG
C17H16FNOSSi (329.47): C 61.97, H 4.89, N 4.25, S 9.73; found: C 62.0, H
4.7, N 4.4, S 9.7.
ACHTUNGTRENNUNGcon(IV) complexes 1–4 and 8–11, the halogeno ligands favor
Synthesis of 3: Bromotrimethylsilane (266 mg, 1.74 mmol) was added in a
single portion at 208C to a stirred suspension of 2 (400 mg, 1.16 mmol) in
acetonitrile (8 mL). The reaction mixture was heated to 958C, and 2 mL
of this mixture were removed by distillation at ambient pressure. The re-
maining solution was slowly cooled to 208C (formation of crystals) and
then kept undisturbed at ꢁ208C for 3 days. The resulting precipitate was
isolated by filtration, washed with diethyl ether (5 mL), and dried in
vacuo (0.01 mbar, 208C, 2 h) to give 3 in 71% yield (320 mg, 820 mmol)
as a yellow crystalline solid. M.p. >1308C (decomp); 1H NMR (CD2Cl2,
pentacoordination in the following rank order: IꢀBr>Cl>
F. This is not what one would expect if it is assumed that
hard ligand atoms should favor pentacoordination of the
hard silicon(IV) coordination center (F>Cl>Br>I). Clear-
ly, this concept is too simple to explain the trend found for
this particular class of compounds. Further studies are nec-
essary to understand this phenomenon.
300.1 MHz): d=2.31 (d, 4J
(1H,1H)=0.6 Hz, 3H; CCH3), 2.34 (s, 3H;
ACHTUNGTRENNUNG
CCH3), 5.80 (q, 4J(1H,1H)=0.6 Hz, 1H; CCHC), 6.96–7.05, 7.16–7.26,
AHCTUNGTRENNUNG
7.39–7.45 ppm (m, 9H; SC6H4N, SiC6H5); 13C NMR (CD2Cl2, 75.5 MHz):
d=24.2 (CCH3), 24.4 (CCH3), 105.4 (CCHC), 123.6, 124.6, 127.0, 127.9 (2
C), 128.8, 129.9, 131.9 (2 C), 134.5, 137.0, 139.6 (SC6H4N, SiC6H5), 171.5
(CN or CO), 171.6 ppm (CN or CO); 29Si NMR (CD2Cl2, 59.6 MHz): d=
ꢁ86.7 ppm; 13C VACP/MAS NMR: d=24.7 (CCH3), 27.1 (CCH3), 106.7
(CCHC), 124.5 (3 C), 126.9 (2 C), 128.6 (2 C), 134.0 (3 C), 137.9 (2 C)
(SC6H4N, SiC6H5), 170.4 (CN or CO), 171.6 ppm (CN or CO); 15N
VACP/MAS NMR: d=ꢁ153.6 ppm; 29Si VACP/MAS NMR: d=
ꢁ89 ppm (br.); elemental analysis calcd (%) for C17H16BrNOSSi
(390.38): C 52.31, H 4.13, N 3.59, S 8.21; found: C 52.3, H 4.1, N 3.6, S
8.2.
Experimental Section
General procedures: All syntheses were carried out under dry nitrogen.
The organic solvents used were dried and purified according to standard
procedures and stored under nitrogen. Melting points were determined
by using a Bꢁchi Melting Point B-540 apparatus using samples in sealed
capillaries. The solution-state 1H, 13C, 19F, and 29Si NMR spectra were re-
corded at 238C by using
a
Bruker DRX-300 (1H, 300.1 MHz; 13C,
75.5 MHz; 29Si, 59.6 MHz), a Bruker Avance 400 (19F, 376.5 MHz), or a
Bruker Avance 500 NMR spectrometer (1H, 500.1 MHz; 13C, 125.8 MHz;
29Si, 99.4 MHz). CD2Cl2, CD3CN, or C6D6 served as the solvent. Chemical
shifts (ppm) were determined relative to internal CHDCl2 (1H, d=
5.32 ppm; CD2Cl2), CHD2CN (1H, d=1.93 ppm; CD3CN), C6HD5 (1H,
d=7.28 ppm; C6D6), CD2Cl2 (13C, d=53.8 ppm; CD2Cl2), CD3CN (13C,
d=1.3 ppm; CD3CN), C6D6 (13C, d=128.0 ppm; C6D6), or external TMS
(29Si, d=0 ppm; CD2Cl2, CD3CN, C6D6). Assignment of the 13C NMR
data was supported by DEPT 135 experiments and 13C,1H correlation ex-
periments. The mixing time for the 1H,1H EXSY experiment was 800 ms.
Solid-state 13C, 15N, and 29Si VACP/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 approximately 300 mg of
sample (13C, 100.6 MHz; 15N, 40.6 MHz; 29Si, 79.5 MHz; external stan-
Synthesis of 5: (Isothiocyanato)trimethylsilane (209 mg, 1.59 mmol) was
added in a single portion at 208C to a stirred suspension of 2 (500 mg,
1.45 mmol) in acetonitrile (11 mL). The reaction mixture was stirred at
208C for 10 min, heated to 708C, and filtered hot. The filtrate was slowly
cooled to 208C (formation of crystals) and then kept undisturbed at
208C for 4 h and then at ꢁ208C for a further 20 h. The resulting precipi-
tate was isolated by filtration, washed with diethyl ether (10 mL), and
dried in vacuo (0.01 mbar, 208C, 2 h) to give 5 in 86% yield (459 mg,
1.25 mmol) as
1H NMR (CD2Cl2, 500.1 MHz): d=2.23 (d, 4J
CCH3), 2.35 (s, 3H; CCH3), 5.77 (q, 4J(1H,1H)=0.6 Hz, 1H; CCHC),
7.00–7.02, 7.12–7.16, 7.22–7.25, 7.27–7.31, 7.41–7.44 ppm (m, 9H;
a
yellow crystalline solid. M.p. >1008C (decomp);
AHCTUNGTRENNUNG
AHCTUNGTRENNUNG
Chem. Eur. J. 2010, 16, 6844 – 6856
ꢂ 2010 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
www.chemeurj.org
6853

R. Tacke et al.
SC6H4N, SiC6H5); 13C NMR (CD2Cl2, 125.8 MHz): d=24.1 (CCH3), 24.3
thane (6 mL), and the resulting solution was kept undisturbed at ꢁ208C
for 3 weeks. The resulting precipitate was isolated by filtration, washed
with n-pentane (15 mL), and dried in vacuo (0.01 mbar, 208C, 2 h) to
give 8 in 13% yield (378 mg, 1.41 mmol) as a pale yellow crystalline
(CCH3), 105.1 (CCHC), 123.7, 124.6, 127.9, 128.1 (2 C), 128.6, 130.3,
1
132.4, 133.1 (2 C), 137.27, 137.34 (SC6H4N, SiC6H5), 135.5 (t, J
N
24 Hz, NCS), 171.6 (CN or CO), 171.7 ppm (CN or CO); 29Si NMR
(CD2Cl2, 99.4 MHz): d=ꢁ98.3 ppm (t, 1J
N
solid. M.p. >1008C (decomp); H NMR (CD3CN, 300.1 MHz):[10] d=0.11
1
ACTHNGUTRENNUG CAHTUNGTRENNUNG
(d, 3J(1H,19F)=6.5 Hz, 3H; SiCH3), 2.10 (d, 4J(1H, 1H)=0.6 Hz, 3H;
CCH3), 2.28 (s, 3H; CCH3), 5.84 (q, 4J
6.55–7.47 ppm (m, 4H; SC6H4N); 13C NMR (CD3CN, 75.5 MHz): d=1.7
(d, J
(13C,19F)=26 Hz, SiCH3), 23.9 (CCH3), 24.0 (CCH3), 104.8 (CCHC),
124.5, 126.3, 127.8 128.9 (d, J
(13C,19F)=3.7 Hz), 134.0 (d, J(13C,19F)=
(13C,19F)=
(1H, 1H)=0.6 Hz, 1H; CCHC),
ACHTUNGTRENNUNG
AHCTUNGTRENNUNG
A
ACHTUNGTRENNUNG
8.0 Hz), 138.9 (SC6H4N), 170.4 (CN or CO), 170.5 ppm (JACHTUNGTRENNUNG
7.5 Hz, CN or CO); 19F NMR (CD3CN, 376.5 MHz): d=ꢁ75.9 ppm; 29Si
Synthesis of 6: Azidotrimethylsilane (250 mg, 2.17 mmol) was added in a
single portion at 208C to a stirred suspension of 2 (600 mg, 1.73 mmol) in
acetonitrile (10 mL). The reaction mixture was heated to 958C, and 2 mL
of this mixture were removed by distillation at ambient pressure. The re-
maining solution was cooled to 208C, and the solid was filtered off and
discarded. The filtrate was slowly concentrated in vacuo to a volume of
approximately 6 mL (formation of crystals) and was then kept undisturb-
NMR (CD3CN, 59.6 MHz): d=ꢁ74.8 ppm (d, 1J
(29Si,19F)=265 Hz); 13C
ACHTUNGTRENNUNG
VACP/MAS NMR: d=2.3 (SiCH3), 24.0 (CCH3), 24.5 (CCH3), 105.4
(CCHC), 123.3, 125.3, 128.6, 129.0, 133.4, 138.1 (SC6H4N), 168.7 (CN or
CO), 171.6 ppm (CN or CO); 15N VACP/MAS NMR: d=ꢁ147.9 ppm;
29Si VACP/MAS NMR: d=ꢁ77.7 ppm (d, 1J
ACHTUNGERTN(NUNG Si,F)=283 Hz); elemental
analysis calcd (%) for C12H14FNOSSi (267.40): C 53.90, H 5.28, N 5.24, S
11.99; found: C 53.7, H 5.4, N 5.4, S 12.0.
A
precipitate was isolated by filtration, washed with diethyl ether (10 mL),
Synthesis of 9: TrichloroACTHNGUTERN(UNG methyl)silane (3.61 g, 24.2 mmol) was added
and dried in vacuo (0.01 mbar, 208C, 2 h) to give 6 in 78% yield (476 mg,
dropwise within 5 min at 208C (water bath) to a stirred mixture of 1-(2-
methyl-2,3-dihydrobenzothiazol-2-yl)propan-2-one (5.00 g, 24.1 mmol),
triethylamine (4.88 g, 48.2 mmol), and tetrahydrofuran (80 mL), and the
resulting mixture was then stirred at 208C for 1 h. The resulting solid was
filtered off, washed with tetrahydrofuran (10 mL), and discarded. The
solvent of the filtrate (including the wash solution) was removed in
vacuo, acetonitrile (25 mL) was added to the residue, and the resulting
suspension was heated until a clear solution was obtained, which was
kept undisturbed at 208C for 4 h and then at ꢁ208C for a further 16 h.
The resulting precipitate was isolated by filtration, washed with diethyl
ether (15 mL), and dried in vacuo (0.01 mbar, 208C, 2 h) to give 9 in
65% yield (4.45 g, 15.7 mmol) as a yellow crystalline solid. M.p. >1208C
(decomp); 1H NMR (CD3CN, 300.1 MHz):[10] d=0.52 (s, 3H; SiCH3),
1.35 mmol) as
1H NMR (CD2Cl2, 500.1 MHz):[10] d=2.25 (d, 4J
CCH3), 2.34 (s, 3H; CCH3), 5.78 (q, 4J(1H,1H)=0.6 Hz, 1H; CCHC),
a
yellow crystalline solid. M.p. >1158C (decomp);
AHCTUNGTRENNUNG
AHCTUNGTRENNUNG
6.97–7.00, 7.09–7.13, 7.21–7.24, 7.26–7.29, 7.39–7.41, 7.43–7.45 ppm (m,
9H; SC6H4N, SiC6H5); 13C NMR (CD2Cl2, 125.8 MHz): d=23.4 (CCH3),
24.1 (CCH3), 104.6 (CCHC), 123.6, 124.3, 127.9 (2 C), 128.1, 128.3, 129.9,
133.2 (2 C), 133.6, 137.70, 137.72 (SC6H4N, SiC6H5), 171.3 (CN or CO),
172.2 ppm (CN or CO); 29Si NMR (CD2Cl2, 99.4 MHz): d=ꢁ87.8 ppm;
13C VACP/MAS NMR: d=20.5 (CCH3), 24.8 (CCH3), 106.7 (CCHC),
124.1, 126.4, 127.6 (2 C), 128.5, 130.5 (3 C), 131.5, 134.5, 138.0 (2 C)
(SC6H4N, SiC6H5), 170.3 (CN or CO), 170.9 ppm (CN or CO); 15N
VACP/MAS NMR: d=ꢁ295.1 (SiNNN), ꢁ210.7 (SiNNN), ꢁ145.4 (CN
or SiNNN), ꢁ140.4 ppm (CN or SiNNN); 29Si VACP/MAS NMR: d=
ꢁ87.1 ppm; elemental analysis calcd (%) for C17H16N4OSSi (352.49): C
57.93, H 4.58, N 15.89, S 9.10; found: C 58.0, H 4.6, N 15.8, S 9.3.
2.12 (d, 4J
(1H,1H)=0.6 Hz, 3H; CCH3), 2.32 (s, 3H; CCH3), 5.79 (q, 4J-
ACHTUNGTRENNUNG
(1H,1H)=0.6 Hz, 1H; CCHC), 7.13–7.25 and 7.36–7.43 ppm (m, 4H;
SC6H4N); 13C NMR (CD3CN, 75.5 MHz): d=8.8 (SiCH3), 24.0 (CCH3),
24.2 (CCH3), 105.9 (CCHC), 124.7, 125.3, 127.8, 129.2, 133.9, 138.0
(SC6H4N), 170.1 (CN or CO), 171.6 ppm (CN or CO); 29Si NMR
(CD3CN, 59.6 MHz): d=ꢁ72.2 ppm; 13C VACP/MAS NMR: d=9.4
(SiCH3), 24.1 (CCH3), 25.4 (CCH3), 106.1 (CCHC), 125.5, 126.1, 127.5,
131.2, 133.5, 137.4 (SC6H4N), 171.1 (CN or CO), 171.7 ppm (CN or CO);
15N VACP/MAS NMR: d=ꢁ152.4 ppm; 29Si VACP/MAS NMR: d=
ꢁ75 ppm (br.); elemental analysis calcd (%) for C12H14ClNOSSi (283.85):
C 50.78, H 4.97, N 4.93, S 11.30; found: C 50.4, H 5.0, N 5.1, S 11.1.
Synthesis of 7: Cyanotrimethylsilane (321 mg, 3.24 mmol) was added in a
single portion at 208C to a stirred suspension of 2 (935 mg, 2.70 mmol) in
acetonitrile (10 mL). The reaction mixture was heated to 958C, 5 mL of
this mixture were removed by distillation at ambient pressure, and the re-
maining solid was filtered off and discarded. The solvent of the filtrate
was removed in vacuo, acetonitrile (5 mL) was added to the residue, and
the resulting suspension was heated until a clear solution was obtained.
This solution was allowed to cool to 208C (formation of crystals) and was
then kept undisturbed at this temperature for 2 h and then at ꢁ208C for
a further 16 h. The resulting precipitate was isolated by filtration, washed
with diethyl ether (10 mL), and dried in vacuo (0.01 mbar, 208C, 2 h) to
give 7 in 61% yield (558 mg, 1.66 mmol) as an orange-colored crystalline
solid. M.p. >1708C (decomp); 1H NMR (CD2Cl2, 500.1 MHz): d=2.25
Synthesis of 10: Bromotrimethylsilane (674 mg, 4.40 mmol) was added in
a single portion at 208C to a stirred suspension of 9 (1.00 g, 3.52 mmol)
in acetonitrile (10 mL), the reaction mixture was heated to 608C, and the
undissolved solid was filtered off and discarded. The filtrate was cooled
to 208C and kept undisturbed at this temperature for 16 h and then at
ꢁ208C for a further 24 h. The resulting precipitate was isolated by filtra-
tion, washed with n-pentane (10 mL), and dried in vacuo (0.01 mbar,
208C, 2 h) to give 10 in 68% yield (790 mg, 2.41 mmol) as a yellow crys-
(d, 4J
ACHTUNGTRENNUNG
ACHTUNGTRENNUNG
(1H,1H)=0.6 Hz, 3H; CCH3), 2.35 (s, 3H; CCH3), 5.78 (q, 4J-
(1H,1H)=0.6 Hz, 1H; CCHC), 6.99–7.03, 7.11–7.32, 7.39–7.52 ppm (m,
9H; SC6H4N, SiC6H5); 13C NMR (CD2Cl2,125.8 MHz): d=24.1 (CCH3),
24.4 (CCH3), 105.4 (CCHC), 123.7, 124.7, 127.9, 128.1 (2 C), 128.7, 130.4,
132.5, 133.5 (2 C), 134.3, 136.8, 137.3 (SC6H4N, SiC6H5, SiCN), 172.1 (SiN
or CO), 172.8 ppm (SiN or CO); 29Si NMR (CD2Cl2, 99.4 MHz): d=
ꢁ99.9 ppm; 13C VACP/MAS NMR: d=23.6 (CCH3), 23.9 (CCH3), 104.2
(CCHC), 124.4, 126.1 (2 C), 127.8, 129.0, 130.2, 131.3, 132.9 (2 C), 136.7,
137.5, 137.8 (2 C) (SC6H4N, SiC6H5, SiCN), 172.0 (SiN or CO), 175.8 ppm
(SiN or CO); 15N VACP/MAS NMR: d=ꢁ158.8 (SiN), ꢁ96.6 (SiCN)
ppm; 29Si VACP/MAS NMR: d=ꢁ100.8 ppm; elemental analysis calcd
(%) for C18H16N2OSSi (336.49): C 64.25, H 4.79, N 8.33, S 9.53; found: C
63.8, H 4.8, N 7.9, S 9.6.
1
talline solid. M.p. >1308C (decomp); H NMR (CD2Cl2, 300.1 MHz): d=
ACTHNUTRGNEUNG
0.76 (s, 3H; SiCH3), 2.19 (d, 4J(1H,1H)=0.5 Hz, 3H; CCH3), 2.38 (s, 3H;
ACTHNUTRGNEUNG
CCH3), 5.73 (q, 4J(1H,1H)=0.5 Hz, 1H; CCHC), 7.12–7.29 and 7.39–
7.42 ppm (m, 4H; SC6H4N); 13C NMR (CD2Cl2, 75.5 MHz): d=10.8
(SiCH3), 24.1 (CCH3), 24.2 (CCH3), 105.4 (CCHC), 123.5, 124.7, 127.4,
128.8, 134.2, 136.9 (SC6H4N), 170.3 (CN or CO), 170.4 ppm (CN or CO);
29Si NMR (CD2Cl2, 59.6 MHz): d=ꢁ75.8 ppm; 13C VACP/MAS NMR:
d=12.0 (SiCH3), 24.3 (CCH3), 25.7 (CCH3), 106.6 (CCHC), 125.5, 126.6
(2 C), 132.0, 133.7, 136.8 (SC6H4N), 171.6 ppm (2 C, CN and CO); 15N
VACP/MAS NMR: d=ꢁ160.2 ppm; 29Si VACP/MAS NMR: d=
ꢁ80 ppm (br.); elemental analysis calcd (%) for C12H14BrNOSSi
(328.30): C 43.90, H 4.30, N 4.27, S 9.77; found: C 43.7, H 4.3, N 4.3, S
9.5.
Synthesis of 8: Ammonium fluoride (421 mg, 11.4 mmol) was added in a
single portion at 208C to a stirred solution of 9 (3.07 g, 10.8 mmol) in tet-
rahydrofuran (40 mL), and the reaction mixture was then stirred at 208C
for 48 h. The resulting solid was filtered off, washed with tetrahydrofuran
(5 mL), and discarded. The solvent of the filtrate (including the wash so-
lution) was removed in vacuo, the residue was dissolved in dichlorome-
Synthesis of 11: Iodotrimethylsilane (441 mg, 2.20 mmol) was added in a
single portion at 208C to a stirred suspension of 9 (500 mg, 1.76 mmol) in
acetonitrile (4 mL), and the resulting mixture was stirred for 2 min and
6854
www.chemeurj.org
ꢂ 2010 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
Chem. Eur. J. 2010, 16, 6844 – 6856

Pentacoordinate (Pseudo)halogenosilicon(IV) Complexes
FULL PAPER
then kept undisturbed at 208C for 16 h and then at ꢁ208C for a further
24 h. The resulting precipitate was isolated by filtration, washed with di-
ethyl ether (5 mL), and dried in vacuo (0.01 mbar, 208C, 2 h) to give 11
in 55% yield (365 mg, 973 mmol) as a yellow crystalline solid. M.p.
NMR: d=23.1 (CCH3), 26.0 (CCH3), 110.6 (CCHC), 120.3, 126.3 (2 C),
128.1, 131.5, 138.8 (SC6H4N), 175.7 (2 C) ppm (CN and CO), SiC6F5 not
well resolved/detectable; 15N VACP/MAS NMR: d=ꢁ171.0 ppm; 29Si
VACP/MAS NMR: d=ꢁ93 ppm (br.); elemental analysis calcd (%) for
C17H11ClF5NOSSi (435.88): C 46.85, H 2.54, N 3.21, S 7.36; found: C 46.9,
H 2.7, N 3.4, S 7.5.
>1208C (decomp); 1H NMR (CD2Cl2, 300.1 MHz): d=0.99 (s, 3H;
4
SiCH3), 2.22 (d, J
G
(q, JACHTUNGTRENNUNG
(1H,1H)=0.4 Hz, 1H; CCHC), 7.16–7.29 and 7.33–7.40 ppm (m, 4H;
4
Synthesis of 14: Compound 14 was synthesized according to reference
[11]; however, it was not obtained as an intermediate, instead it was iso-
lated and characterized: A solution of 1-bromo-4-(trifluoromethyl)ben-
zene (8.34 g, 37.1 mmol) in diethyl ether (10 mL) was added dropwise
within 30 min to a stirred suspension of magnesium turnings (901 mg,
37.0 mmol) in diethyl ether (20 mL), causing the reaction mixture to boil
under reflux. The mixture was heated under reflux for a further 2 h,
cooled to 208C, and then added dropwise at 208C within 20 min to a
stirred solution of tetrachlorosilane (25.2 g, 148 mmol) in diethyl ether
(60 mL). The mixture was then heated under reflux for 2 h, allowed to
cool to 208C, and stirred at 208C for 48 h. The resulting solid was filtered
off, washed with diethyl ether (10 mL), and discarded. The solvent of the
filtrate (including the wash solution) and the excess tetrachlorosilane
were removed under reduced pressure, and the residue was purified by
distillation in vacuo to yield 14 in 36% as a colorless liquid (3.77 g,
13.5 mmol). B.p. 70–728C/8 mbar; 1H NMR (C6D6, 500.1 MHz): d=7.23–
7.27 and 7.39–7.44 ppm (m, 4H; SiC6H4CF3); 13C NMR (C6D6,
SC6H4N); 13C NMR (CD2Cl2, 75.5 MHz): d=13.2 (SiCH3), 24.3 (CCH3),
24.4 (CCH3), 106.3 (CCHC), 123.6, 125.0, 126.9, 129.1, 134.6, 136.3
(SC6H4N), 170.4 (CN or CO), 171.6 ppm (CN or CO); 29Si NMR
(CD2Cl2, 59.6 MHz): d=ꢁ75.6 ppm; 13C VACP/MAS NMR: d=12.5
(SiCH3), 23.5 (CCH3), 25.3 (CCH3), 109.7 (CCHC), 124.9, 127.5 (2 C),
132.1, 134.5, 136.5 (SC6H4N), 169.3 (CN or CO), 172.8 ppm (CN or CO);
15N VACP/MAS NMR: d=ꢁ169.0 ppm; 29Si VACP/MAS NMR: d=
ꢁ72 ppm (br.); elemental analysis calcd (%) for C12H14INOSSi (375.31):
C 38.40, H 3.76, N 3.73, S 8.54; found: C 37.8, H 3.7, N 3.8, S 8.5.
Synthesis of 12: Compound 14 (1.45 g, 5.19 mmol) was added dropwise
within 5 min at 208C (water bath) to a stirred solution of 1-(2-methyl-2,3-
dihydrobenzothiazol-2-yl)propan-2-one (1.07 g, 5.16 mmol) and triethyl-
ACHTUNGTRENNUNGamine (1.05 g, 10.4 mmol) in tetrahydrofuran (20 mL), and the resulting
mixture was then stirred at 208C for 3 h. The resulting solid was filtered
off, washed with tetrahydrofuran (10 mL), and discarded. The solvent of
the filtrate (including the wash solution) was removed in vacuo, acetoni-
trile (6 mL) was added to the residue, and the resulting suspension was
1
3
125.8 MHz): d=124.0 (q, J
3.8 Hz, C-3/C-5, SiC6H4CF3), 133.7 (br., C-2/C-6, SiC6H4CF3), 134.1 (q, J-
(13C,19F)=273 Hz, CF3), 125.3 (q, J(13C,19F)=
ACHUTGTNRENNUG ACHTUNGTRENNUNG
2
heated until
a clear solution was obtained, which was then kept
5
ACHUTNGRENNUG CAHTUNGTRENNUGN
(13C,19F)=33 Hz, C-4, SiC6H4CF3), 135.3 ppm (q, J(13C,19F)=1.2 Hz, C-1,
undisturbed at 208C for 16 h. The resulting precipitate was isolated by fil-
ACHTUNGTRENNUNG
SiC6H4CF3); 19F NMR (C6D6, 376.5 MHz): d=ꢁ63.2 ppm; 29Si NMR
tration, washed with diethyl ether (10 mL), and dried in vacuo
(C6D6, 99.4 MHz): d=ꢁ1.6 ppm.
(0.01 mbar, 208C, 2 h) to give 13 in 65% yield (1.38 g, 3.33 mmol) as a
yellow-orange crystalline solid. M.p. >1228C (decomp); 1H NMR
Synthesis of 15: Compound 15 was synthesized according to refer-
4
(CD3CN, 500.1 MHz): d=2.23 (d, J
(1H,1H)=0.6 Hz, 3H; CCH3), 2.32 (s,
ence [12].
3H; CCH3), 5.94 (q, JACHTUNGTRENNUNG
(1H,1H)=0.6 Hz, 1H; CCHC), 6.99–7.20 and 7.38–
4
Crystal structure analyses: Suitable single crystals of compounds 1, 3, 5–
8, and 10–13 were isolated directly from the respective reaction mixtures.
Compound 9 was crystallized by cooling of a saturated solution in di-
chloromethane to 48C. The crystals were mounted in inert oil (perfluoro-
polyalkyl ether, ABCR) on a glass fiber and then transferred to the cold
nitrogen gas stream of the diffractometer (1, 3, 9, and 10: Bruker Nonius
KAPPA APEX II, Montel mirror, MoKa radiation, l=0.71073 ꢃ; 5–8
and 11–13: Stoe IPDS, graphite-monochromated MoKa radiation, l=
0.71073 ꢃ). All structures were solved by direct methods.[13] The non-hy-
drogen atoms were refined anisotropically.[13] A riding model was em-
ployed in the refinement of the CH hydrogen atoms. CCDC-765906 (1),
CCDC-765907 (3), CCDC-765908 (5), CCDC-765909 (6), CCDC-765910
(7), CCDC-765911 (8), CCDC-765912 (9), CCDC-765913 (10), CCDC-
765914 (11), CCDC-765915 (12), and CCDC-765916 (13) contain the sup-
plementary crystallographic data for this paper. These data can be ob-
tained free of charge from The Cambridge Crystallographic Data Centre
via www.ccdc.cam.ac.uk/data_request/cif.
7.66 ppm (m, 8H; SC6H4N, SiC6H4CF3); 13C NMR (CD3CN, 125.8 MHz):
d=24.1 (CCH3), 24.5 (CCH3), 106.0 (CCHC), 124.8 (SC6H4N), 125.0 (q,
3J(13C,19F)=3.8 Hz, C-3/C-5, SiC6H4CF3), 125.2 (q, 1J(13C,19F)=271 Hz,
ACHTUNGTRENNUNG ACHTUNGTRENNUGN
CF3), 125.4 (SC6H4N), 127.6 (SC6H4N), 129.4 (SC6H4N), 131.4 (q, 2J-
(13C,19F)=32 Hz, C-4, SiC6H4CF3), 133.58 (SC6H4N), 133.64 (br. s, C-2/C-
6, SiC6H4CF3), 137.8 (SC6H4N), 145.9 (q, 5J(13C,19F)=1.3 Hz, C-1,
ACHTUNGTRENNUNG
AHCTUNGTRENNUNG
SiC6H4CF3), 171.8 (CN or CO), 173.9 ppm (CN or CO); 19F NMR
(CD3CN, 376.5 MHz): d=ꢁ63.5 ppm; 29Si NMR (CD3CN, 99.4 MHz): d=
ꢁ84.3 ppm; 13C VACP/MAS NMR: d=24.0 (CCH3), 27.0 (CCH3), 108.6
(CCHC), 126.2 (7 C), 127.5, 130.6, 132.1, 138.9, 144.9 (SC6H4N,
SiC6H4CF3), 168.8 (CN or CO), 172.6 ppm (CN or CO), CF3 not detect-
ed; 15N VACP/MAS NMR: d=ꢁ152.1 ppm; 29Si VACP/MAS NMR: d=
ꢁ84 ppm (br.); elemental analysis calcd (%) for C18H15ClF3NOSSi
(413.92): C 52.23, H 3.65, N 3.38, S 7.75; found: C 52.0, H 3.6, N 3.6, S
7.8.
Synthesis of 13: Compound 15 (1.58 g, 5.24 mmol) was added dropwise
within 5 min at 208C (water bath) to a stirred solution of 1-(2-methyl-2,3-
dihydrobenzothiazol-2-yl)propan-2-one (1.09 g, 5.26 mmol) and triethyla-
mine (1.06 g, 10.5 mmol) in tetrahydrofuran (20 mL), and the resulting
mixture was stirred at 208C for 2 h. The resulting solid was filtered off,
washed with tetrahydrofuran (10 mL), and discarded. The solvent of the
filtrate (including the wash solution) was removed in vacuo, acetonitrile
(7 mL) was added to the residue, and the resulting suspension was
heated until a clear solution was obtained, which was then kept undistur-
bed at 208C for 14 h and then at ꢁ208C for a further 3 h. The resulting
precipitate was isolated by filtration, washed with diethyl ether (10 mL),
and dried in vacuo (0.01 mbar, 208C, 3 h) to give 13 in 59% yield (1.34 g,
3.07 mmol) as a yellow-brown crystalline solid. M.p. >1658C (decomp);
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ACTHNUTRGNEUNG
1H NMR (CD2Cl2, 500.1 MHz): d=2.27 (d, 4J(1H,1H)=0.5 Hz, 3H;
ACTHNUTRGNEUNG
CCH3), 2.34 (s, 3H; CCH3), 5.85 (q, 4J(1H,1H)=0.5 Hz, 1H; CCHC),
7.01–7.09, 7.20–7.25, 7.46–7.50 ppm (m, 4H; SC6H4N); 13C NMR (CD2Cl2,
125.8 MHz): d=24.2 (CCH3), 24.4 (CCH3), 105.6 (CCHC), 123.3, 124.9,
1
127.5, 129.0, 133.1, 136.6 (SC6H4N), 113.4 (m, C-1, SiC6F5), 137.4 (dm, J-
ACHTUNGTRENNUNG ACHTUNGTRENNUGN
(13C,19F)=245 Hz, C-2/C-6, SiC6F5), 142.0 (dm, 1J(13C,19F)=254 Hz, C-4,
ACHTUNGTRENNUNG
SiC6F5), 147.7 (dm, 1J(13C,19F)=240 Hz, C-3/C-5, SiC6F5), 171.5 (CN or
CO), 171.9 ppm (CN or CO); 19F NMR (CD2Cl2, 376.5 MHz): d=ꢁ162.4
to ꢁ162.0, ꢁ153.5 to ꢁ153.2, ꢁ130.2 to ꢁ130.0 ppm (m, 5 F, SiC6F5); 29Si
NMR (CD2Cl2, 99.4 MHz): d=ꢁ92.3 to ꢁ92.0 (m) ppm; 13C VACP/MAS
Chem. Eur. J. 2010, 16, 6844 – 6856
ꢂ 2010 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
www.chemeurj.org
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Received: January 20, 2010
Published online: May 6, 2010
6856
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Chem. Eur. J. 2010, 16, 6844 – 6856