Stable five-coordinate silicon(IV) complexes with SiN4X skeletons (X=S, Se, Te) and Si=X double bonds

Article abstract of DOI:10.1002/chem.201202936

Silylenes: Reaction of the donor-stabilized silylene 1 with elemental sulfur, selenium, or tellurium led to the formation of 2 a-c [SiN₄X skeletons (X=S, Se, Te)], the first stable five-coordinate silicon(IV) compounds with silicon-chalcogen double bonds (see figure).

Full text of DOI:10.1002/chem.201202936

DOI: 10.1002/chem.201202936
Stable Five-Coordinate Silicon(IV) Complexes with SiN4X Skeletons
(X=S, Se, Te) and Si=X Double Bonds
Konstantin Junold, Johannes A. Baus, Christian Burschka, Dominic Auerhammer, and
Reinhold Tacke*[a]
Recently, we have reported the synthesis of the three-co-
ordinate silicon(II) compound 1, a donor-stabilized thermal-
ly stable silylene with one bidentate and one monodentate
amidinato ligand.[1] Treatment of 1 with iodine resulted in
an oxidative addition to give the six-coordinate silicon(IV)
complex 2 (SiN4I2 skeleton); that is, in the formation of 2,
both amidinato ligands of 1 act as bidentate ligands (l3SiII!
l6SiIV).[1] This result prompted us to study an analogous re-
action of 1 with the chalcogens sulfur, selenium, or telluri-
um, which should potentially afford five-coordinate sili-
ACHTUNGTRENNUNG
AHCTUNGTRENNUNG
compounds with Si=X double bonds have already been re-
ported in the literature,[2–11] such as 3a–c,[3] 4a–d,[4] 5a–c,[5]
6a,[6] 6b,[7] 7,[7] 8,[8] 9a–f,[9] and 10a–c.[10] However, all these
compounds represent three- or four-coordinate silicon(IV)
compounds, whereas the reaction of 1 with sulfur, selenium,
or tellurium was expected to lead to a new type of five-coor-
dinate silicon(IV) complexes with Si=X bonds.
Indeed, treatment of 1 with one molar equivalent of ele-
mental sulfur, selenium, or tellurium in toluene at 208C re-
sulted in the formation of compounds 11a–c, which were
isolated as crystalline solids (yield: 11a 51%; 11b 46%; 11c
72%; Scheme 1).[12] So far, attempts to prepare the corre-
sponding oxygen analogue of 11a–c failed. The identities of
11a–c were established by elemental analyses, NMR spec-
troscopic studies in the solid state and in solution,[13] as well
as crystal structure analyses.[14] The crystal structure of 11c
was determined with the toluene solvate 11c·0.7C6H5CH3.
The molecular structures of 11a–c are depicted in Figures 1–
3. The studies reported herein were performed in continua-
tion of our systematic investigations on higher-coordinate
silicon(IV) and silicon(II) compounds.[1,15]
Scheme 1. Syntheses of compounds 11a–c.
[a] K. Junold, J. A. Baus, Dr. C. Burschka, D. Auerhammer,
Prof. Dr. R. Tacke
Universitꢀt Wꢁrzburg
Institut fꢁr Anorganische Chemie
Am Hubland, 97074 Wꢁrzburg (Germany)
Fax : (+49)931-31-84609
The silicon coordination polyhedra of 11a (two molecules
in the asymmetric unit), 11b, and 11c·0.7C6H5CH3 (disor-
dered toluene molecules) are best described as strongly dis-
E-mail: r.tacke@uni-wuerzburg.de
16288
ꢂ 2012 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
Chem. Eur. J. 2012, 18, 16288 – 16291

COMMUNICATION
Figure 1. Molecular structure of 11a (molecule 1) in the crystal (ellipsoids
were set at 50% probability; hydrogen atoms were omitted for clarity).
Figure 2. Molecular structure of 11b in the crystal (ellipsoids were set at
50% probability; hydrogen atoms were omitted for clarity). Selected
ꢀ
ꢀ
Selected bond lengths [ꢃ] and angles [8]: Si S 2.0193(9), Si N1
ꢀ
ꢀ
ꢀ
ꢀ
1.8209(17), Si N2 1.9611(16), Si N3 1.9562(16), Si N4 1.8148(16), N1
ꢀ
ꢀ
ꢀ
bond lengths [ꢃ] and angles [8]: Si Se 2.1632(7), Si N1 1.8153(18), Si
ꢀ
ꢀ
ꢀ
C1 1.347(2), N2 C1 1.318(2), N3 C14 1.309(2), N4 C14 1.359(2); S-Si-
N1 123.43(6), S-Si-N2 103.55(6), S-Si-N3 100.32(6), S-Si-N4 123.90(6),
N1-Si-N2 69.07(7), N1-Si-N3 98.99(7), N1-Si-N4 112.67(8), N2-Si-N3
156.07(7), N2-Si-N4 95.91(7), N3-Si-N4 68.88(7), N1-C1-N2 107.38(16),
ꢀ
ꢀ
ꢀ
ꢀ
N2 1.9534(18), Si N3 1.9550(17), Si N4 1.813(2), N1 C1 1.338(3), N2
ꢀ
ꢀ
C1 1.314(3), N3 C14 1.306(3), N4 C14 1.356(3); Se-Si-N1 123.73(7), Se-
Si-N2 102.72(6), Se-Si-N3 99.50(5), Se-Si-N4 123.19(6), N1-Si-N2
68.96(8), N1-Si-N3 98.92(8), N1-Si-N4 113.07(9), N2-Si-N3 157.77(8), N2-
Si-N4 97.99(9), N3-Si-N4 68.90(8), N1-C1-N2 107.32(18), N3-C14-N4
106.64(19).
ꢀ
ꢀ
ꢀ
N3-C14-N4 106.33(15); molecule 2: Si S 2.0229(9), Si N1 1.8358(16), Si
ꢀ
ꢀ
ꢀ
ꢀ
N2 1.9501(15), Si N3 1.9682(15), Si N4 1.8231(16), N1 C1 1.351(2), N2
ꢀ
ꢀ
C1 1.310(2), N3 C14 1.314(2), N4 C14 1.345(2); S-Si-N1 123.66(6), S-Si-
N2 99.65(5), S-Si-N3 102.02(6), S-Si-N4 125.01(6), N1-Si-N2 68.83(7), N1-
Si-N3 99.46(7), N1-Si-N4 111.30(8), N2-Si-N3 158.31(7), N2-Si-N4
97.71(7), N3-Si-N4 68.79(7), N1-C1-N2 107.16(15), N3-C14-N4
107.57(15).
ꢀ
ꢀ
compounds with Si X single bonds (Si S 2.1251(7)–
ꢀ
ꢀ
2.2087(8); Si Se 2.2846(4)–2.3449(7); Si Te 2.5184(4)–
2.5608(12) ꢃ),[17] indicating a considerable double bond
ꢀ
character of the silicon–chalcogen bonds in 11a–c. The N C
torted trigonal bipyramids, with one nitrogen atom of each
of the two amidinato ligands in the axial positions (Nax-Si-
Nax 156.07(7) and 158.31(7) (11a), 157.77(8) (11b),
157.29(7)8 (11c); sum of the equatorial bond angles 360.08
(11a–c)). The Berry distortions (transition trigonal bipyra-
mid ! square pyramid) amount to 18.9/14.8% (11a),
bond lengths in the amidinato ligands of 11a–c (1.306(3)–
1.359(2) ꢃ) are very similar, which can be explained by a
high degree of electron delocalization within the NCN skel-
ꢀ
ꢀ
etons (Nax =CPh Neq $ Nax CPh=Neq). However, it is inter-
ꢀ
esting to note that the Nax
C
distances (1.306(3)–
ꢀ
1.318(2) ꢃ) are slightly shorter than the Neq C bond lengths
(1.338(2)–1.359(2) ꢃ), indicating a small preference of the
17.5% (11b), and 15.3% (11c).[16] The equatorial Si N
ꢀ
ꢀ
bond lengths (1.813(2)–1.8358(16) ꢃ) are significantly short-
resonance structure Nax=CPh Neq.
ꢀ
er than the axial Si N distances (1.9327(17)–1.9682(15) ꢃ),
The isotropic 29Si chemical shifts of 11a (d=ꢀ74.7 (solid
state)/ꢀ70.7 ppm (solution)), 11b (d=ꢀ85.0/ꢀ80.8 ppm),
and 11c (d=ꢀ111.4/ꢀ116.5 ppm) and the isotropic 77Se and
125Te chemical shifts of 11b (d=ꢀ485.3/ꢀ495.7 ppm) and
11c (d=ꢀ1208.8/ꢀ1199.2 ppm), respectively, in the solid
state and in solution (C6D6) are very similar, indicating that
these three compounds exist also in solution. At 238C, the
1H NMR spectra of 11a–c showed only one doublet and one
ꢀ
and the Si X bond lengths (X=S, Se, Te) amount to
2.0193(9) and 2.0229(9) (11a), 2.1632(7) (11b), and
ꢀ
2.4017(6) ꢃ (11c). These Si X bond lengths are slightly
longer than those of the three- and four-coordinate sili-
ACHTUNGTRENNUNGcon(IV) compounds with Si=X double bonds described in
ꢀ
the literature. For comparison, the reported Si X bond
lengths for Si=X double bonds are in the ranges 1.948(4)–
2.013(3) (Si=S), 2.0963(5)–2.156(1) (Si=Se), and 2.3210(6)–
2.383(2) ꢃ (Si=Te).[3–10] This slight increase is in line with
the change of the silicon coordination number from three or
septet for the four CH
spectra revealed only two resonance signals for the four
CH(CH3)2 groups, indicating a rapid exchange of the four
(CH3)2 groups, and the 13C{1H} NMR
ACHTUNGTRENNUNG
AHCTUNGTRENNUNG
ꢀ
four to five. However, the Si X bond lengths of 11a–c are
significantly shorter than those reported for the respective
nitrogen sites of the two bidentate amidinato ligands. This
assumption was further supported by the 15N{1H} NMR
spectrum of 11b, which showed only one resonance signal at
ꢀ
equatorial Si X distances of five-coordinate sili
N
Chem. Eur. J. 2012, 18, 16288 – 16291
ꢂ 2012 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
www.chemeurj.org
16289

R. Tacke et al.
Compound 11a: Toluene (10 mL) was added at 208C to a mixture of
sulfur (37.0 mg, 144 mmol of S8) and 1 (500 mg, 1.15 mmol), and the reac-
tion mixture was stirred at this temperature for 15 h. The resulting sus-
pension was concentrated in vacuo to a volume of 2 mL and heated until
a clear solution was obtained, which was then cooled slowly to ꢀ208C
and kept undisturbed at this temperature for two days. The resulting col-
orless crystalline solid was isolated by filtration, washed with n-pentane
(2ꢄ5 mL), and dried in vacuo (208C, 4 h, 0.01 mbar). Yield: 272 mg (583
mmol, 51%). M.p. 2138C (decomp); 1H NMR (500.1 MHz, C6D6): d=
1.43 (d, 3J(1H,1H)=6.8 Hz, 24H; CH3), 3.93 (sept, 3J(1H,1H)=6.8 Hz,
ACTHNUTRGENNUG CAHTUNGTRENNUGN
4H; CH3CHCH3), 7.08–7.17 and 7.19–7.28 ppm (m, 10H; C6H5);
13C{1H} NMR (125.8 MHz, C6D6): d=24.1 (8C; CH3), 47.2 (4C;
CH3CHCH3), 128.1 (4C; o-C6H5), 128.5 (4C; m-C6H5); 130.2 (2 C; p-
C6H5), 131.9 (2C; i-C6H5), 172.1 ppm (2C; NCN); 29Si{1H} NMR
(99.4 MHz, C6D6): d=ꢀ70.7 ppm; 15N VACP/MAS NMR (40.6 MHz):
d=ꢀ224.4, ꢀ222.6, ꢀ196.0, ꢀ174.9 ppm; 29Si VACP/MAS NMR
(79.5 MHz): d=ꢀ74.7 ppm (br); elemental analysis (%) calcd for
C26H38N4SSi (466.77): C 66.90, H 8.21, N 12.00, S 6.87; found: C 66.4, H
8.1, N 12.3, S 6.9.
Compound 11b: Toluene (10 mL) was added at 208C to a mixture of
gray selenium (54.5 mg, 690 mmol) and 1 (300 mg, 690 mmol), and the re-
action mixture was stirred at this temperature for 20 h. The insoluble
components were filtered off and discarded, and the filtrate was concen-
trated in vacuo to a volume of 1 mL. The resulting suspension was
heated until a clear solution was obtained, which was then cooled slowly
to ꢀ208C and kept undisturbed at this temperature for two days. The re-
sulting yellow crystalline solid was isolated by filtration, washed with n-
pentane (2ꢄ3 mL), and dried in vacuo (208C, 5 h, 0.01 mbar). Yield:
162 mg (315 mmol, 46%). M.p. 1968C (decomp); 1H NMR (500.1MHz,
Figure 3. Molecular structure of 11c in the crystal of 11c·0.7C6H5CH3 (el-
lipsoids were set at 50% probability; hydrogen atoms were omitted for
ꢀ
ꢀ
clarity). Selected bond lengths [ꢃ] and angles [8]: Si Te 2.4017(6), Si N1
C6D6): d=1.42 (d, 3J(1H,1H)=6.8 Hz, 24H; CH3), 4.00 (sept, 3J(1H,1H)=
ACTHNUTRGENNUG ACHTUNGTRENNUNG
ꢀ
ꢀ
ꢀ
ꢀ
1.8326(18), Si N2 1.9327(17), Si N3 1.9474(17), Si N4 1.8226(17), N1
ꢀ
ꢀ
ꢀ
C1 1.345(3), N2 C1 1.318(3), N3 C14 1.313(3), N4 C14 1.346(2); Te-Si-
N1 126.42(6), Te-Si-N2 101.78(5), Te-Si-N3 100.93(5), Te-Si-N4 122.62(6),
N1-Si-N2 69.30(7), N1-Si-N3 97.27(8), N1-Si-N4 110.96(8), N2-Si-N3
157.29(7), N2-Si-N4 97.86(8), N3-Si-N4 69.14(7), N1-C1-N2 107.15(17),
N3-C14-N4 107.30(17).
6.8 Hz, 4H; CH3CHCH3), 7.10–7.18 and 7.20–7.26 ppm (m, 10H; C6H5);
13C{1H} NMR (125.8MHz, C6D6): d=24.1 (8C; CH3), 47.0 (4C;
CH3CHCH3), 128.1 (4C; o-C6H5), 128.5 (4C; m-C6H5), 130.2 (2C; p-
C6H5), 131.8 (2C; i-C6H5), 171.7 ppm (2C; NCN); 15N{1H} NMR
(50.7MHz, C6D6): d=ꢀ208.9 ppm; 29Si{1H} NMR (99.4MHz, C6D6): d=
ꢀ80.8 ppm (77Se satellites, 1J(29Si,77Se)=291.9 Hz); 77Se{1H} NMR
(95.4MHz, C6D6): d=ꢀ495.7 ppm; 15N VACP/MAS NMR (40.6MHz):
d=ꢀ225.1
(2N),
ꢀ196.0,
ꢀ173.1 ppm;
29Si VACP/MAS NMR
(79.5MHz): d=ꢀ85.0 ppm (77Se satellites, 1J(29Si,77Se)=268 Hz);
77Se VACP/MAS NMR (76.3MHz): d=ꢀ485.3; elemental analysis (%)
calcd for C26H38N4SeSi (513.66): C 60.80, H 7.46, N 10.91; found: C 60.5,
H 7.5, N 10.9.
d=ꢀ208.9 ppm (solid state: d=ꢀ225.1 (2N), ꢀ196.0,
ꢀ173.1 ppm).
In conclusion, starting from the easily accessible tri-coor-
dinate silicon(II) compound 1, the five-coordinate sili-
Compound 11c: Toluene (15 mL) was added at 208C to a mixture of tel-
lurium (147 mg, 1.15 mmol) and 1 (500 mg, 1.15 mmol), and the reaction
mixture was stirred at this temperature for 16 h. The insoluble compo-
nents were filtered off and discarded, and the filtrate was concentrated in
vacuo to a volume of 3 mL. The resulting suspension was heated until a
clear solution was obtained, which was then cooled slowly to ꢀ208C and
kept undisturbed at this temperature for one day. The resulting yellow
crystalline solid was isolated by filtration, washed with n-pentane (2ꢄ
3 mL), and dried in vacuo (208C, 5 h, 0.01 mbar). Yield: 468 mg
(832 mmol, 72%). M.p. 2428C (decomp); 1H NMR (500.1MHz, C6D6):
ACHTUNGTRENNUNGcon(IV) complexes 11a–c were synthesized by oxidative ad-
dition with sulfur, selenium, or tellurium (transformations of
the type l3SiII ! l5SiIV). These compounds represent a new
class of five-coordinate silicon(IV) species with SiN4X skele-
tons (X=S, Se, Te) and thermally stable Si=X double bonds.
Five-coordinate silicon(IV) compounds with silicon–chalco-
gen double bonds have not yet been reported. The synthesis
of 11a–c emphasizes once again the high synthetic potential
of the donor-stabilized silylene 1.[1] Future studies have to
evaluate the chemical reactivity of the Si=X double bonds
of 11a–c and the synthetic potential of these compounds for
the chemistry of higher-coordinate silicon.
d=1.39 (d, 3J(1H,1H)=6.8 Hz, 24H; CH3), 4.04 (sept, 3J(1H,1H)=6.8 Hz,
ACTHNUTRGENNUG CAHTUNGTRENNUGN
4H; CH3CHCH3), 7.10–7.18 and 7.19–7.22 ppm (m, 10H; C6H5);
13C{1H} NMR (125.8 MHz, C6D6): d=24.4 (8C; CH3), 46.8 (4C;
CH3CHCH3), 128.0 (4C; o-C6H5; overlapping with the solvent signal),
128.6 (4C; m-C6H5), 130.3 (2C; p-C6H5), 131.8 (2C; i-C6H5), and
170.9 ppm (2C; NCN); 29Si{1H} NMR (99.4MHz, C6D6): d=ꢀ116.5 ppm
(
125Te satellites, 1J(29Si,125Te) =832 Hz); 125Te{1H} NMR (157.8MHz,
C6D6): d=ꢀ1199.2 ppm; 15N VACP/MAS NMR (40.6MHz): d=ꢀ224.8,
ꢀ222.5, ꢀ186.7, ꢀ184.9 ppm; 29Si VACP/MAS NMR (79.5MHz): d=
Experimental Section
ꢀ111.4 ppm
(
125Te satellites, 1J(29Si,125Te) =809 Hz); 125Te{1H} HPDec/
MAS NMR (126.2MHz): d=ꢀ1208.8 ppm; elemental analysis (%) calcd
for C26H38N4SiTe (562.30): C 55.54, H 6.81, N 9.96; found: C 55.1, H 6.9,
N 9.9.
The syntheses were carried out under a dry argon atmosphere in oven-
dried glassware by using standard Schlenk techniques. The solvents were
dried, purified, and deoxygenated according to standard procedures. The
gray selenium (99.7%; ABCR, product no. AB118648, <70 m) and tellu-
rium (99.8%; Acros Organics, product no. 31599, 200 mesh) were used as
powders. Melting points were measured in sealed glass capillaries by
using a Bꢁchi Melting Point B-540 apparatus.
16290
www.chemeurj.org
ꢂ 2012 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
Chem. Eur. J. 2012, 18, 16288 – 16291

Five-Coordinate Silicon(IV) Complexes
COMMUNICATION
gen gas stream of the diffractometer (11a: Stoe IPDS, graphite-
monochromated MoKa radiation, l=0.71073 ꢃ; 11b and
11c·0.7C6H5CH3: Bruker Nonius KAPPA APEX II, Montel mirror,
MoKa radiation, l=0.71073 ꢃ). The structures were solved by direct
methods (SHELXS-97) and refined by full-matrix least-squares
methods on F2 for all unique reflections (SHELXL-97).[18] For the
CH hydrogen atoms, a riding model was employed. CCDC-888842
(11a), CCDC-888843 (11b), and CCDC-888844 (11c·0.7C6H5CH3)
contain the supplementary crystallographic 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. Selected data for 11a: single crystal of dimensions 0.7ꢄ0.25ꢄ
0.25 mm obtained by crystallization from toluene at ꢀ208C;
C26H38N4SSi; Mr =466.75; analysis at 173(2) K; monoclinic; space
group P21/c (no. 14); a=17.987(3), b=16.210(3), c=19.063(3) ꢃ;
Keywords: selenium · silicon compounds · silylenes · sulfur ·
tellurium
[1] K. Junold, J. A. Baus, C. Burschka, R. Tacke, Angew. Chem. 2012,
124, 7126–7129; Angew. Chem. Int. Ed. 2012, 51, 7020–7023.
[2] For reviews dealing with silicon(IV) compounds with Si=X double
bonds (X=S, Se, Te), see: a) R. Okazaki, N. Tokitoh, Acc. Chem.
Res. 2000, 33, 625–630; b) N. Tokitoh, R. Okazaki, Adv. Organomet.
Chem. 2001, 47, 121–166.
[3] P. Arya, J. Boyer, F. Carrꢅ, R. Corriu, G. Lanneau, J. Lapasset, M.
Perrot, C. Priou, Angew. Chem. 1989, 101, 1069–1071; Angew.
Chem. Int. Ed. Engl. 1989, 28, 1016–1018.
[4] a) H. Suzuki, N. Tokitoh, S. Nagase, R. Okazaki, J. Am. Chem. Soc.
1994, 116, 11578–11579; b) H. Suzuki, N. Tokitoh, R. Okazaki, S.
Nagase, M. Goto, J. Am. Chem. Soc. 1998, 120, 11096–11105; c) N.
Tokitoh, T. Sadahiro, K. Hatano, T. Sasaki, N. Takeda, R. Okazaki,
Chem. Lett. 2002, 34–35.
[5] T. Iwamoto, K. Sato, S. Ishida, C. Kabuto, M. Kira, J. Am. Chem.
Soc. 2006, 128, 16914–16920.
[6] C.-W. So, H. W. Roesky, R. B. Oswald, A. Pal, P. G. Jones, Dalton
Trans. 2007, 5241–5244.
[7] S.-H. Zhang, H.-X. Yeong, C.-W. So, Chem. Eur. J. 2011, 17, 3490–
3499.
b=105.88(2)8; V=5346.2(16) ꢃ3; Z=8; 1calcd =1.160 gcmꢀ3
; m=
0.186 mmꢀ1; F
AHCTUNGTRENNUNG
tions; 10363 unique reflections (Rint =0.0689); 593 parameters; S=
0.991; R1 =0.0392, [I>2s(I)]; wR2 (all data)=0.0863; max/min resid-
ual electron density=+0.429/ꢀ0.273 eꢃꢀ3. Selected data for 11b:
single crystal of dimensions 0.5ꢄ0.4ꢄ0.3 mm obtained by crystalliza-
tion from toluene at ꢀ208C; C26H38N4SeSi; Mr =513.65; analysis at
100(2) K; monoclinic; space group P21/n (no. 14); a=11.1400(7), b=
16.3972(11), c=14.7306(9) ꢃ; b=92.894(2)8; V=2687.3(3) ꢃ3; Z=
4; 1calcd =1.270 gcmꢀ3; m=1.462 mmꢀ1; F
ACHTNUTRGNEG(UN 000)=1080; 2qmax =52.848;
[8] A. Mitra, J. P. Wojcik, D. Lecoanet, T. Mꢁller, R. West, Angew.
Chem. 2009, 121, 4130–4133; Angew. Chem. Int. Ed. 2009, 48, 4069–
4072.
[9] S. Yao, Y. Xiong, M. Driess, Chem. Eur. J. 2010, 16, 1281–1288.
[10] a) S. Yao, Y. Xiong, M. Brym, M. Driess, Chem. Asian J. 2008, 3,
113–118; b) J. D. Epping, S. Yao, M. Karni, Y. Apeloig, M. Driess, J.
Am. Chem. Soc. 2010, 132, 5443–5455.
[11] For stable tetracoordinate silicon(IV) compounds with Si=O double
bonds, see: a) Y. Xiong, S. Yao, M. Driess, J. Am. Chem. Soc. 2009,
131, 7562–7563; b) Y. Xiong, S. Yao, R. Mꢁller, M. Kaupp, M.
Driess, Nat. Chem. 2010, 2, 577–580.
79882 collected reflections; 5518 unique reflections (Rint =0.0529);
327 parameters; 25 restraints; S=1.046; R1 =0.0334 [I>2s(I)]; wR2
(all data)=0.0734; max/min residual electron density=+0.536/
ꢀ0.984 eꢃꢀ3. Selected data for 11c·0.7C6H5CH3: single crystal of di-
mensions 0.5ꢄ0.4ꢄ0.3 mm obtained by crystallization from toluene
at ꢀ208C; C26H38N4SiTe·0.7C6H5CH3; Mr =626.97; analysis at
100(2) K; monoclinic; space group P21/n (no. 14); a=11.6736(8), b=
16.2635(12), c=17.2246(13) ꢃ; b=104.762(2)8; V=3162.2(4) ꢃ3;
Z=4; 1calcd =1.317 gcmꢀ3
;
m=1.003 mmꢀ1
;
F
G
=
55.908; 190882 collected reflections; 7594 unique reflections (Rint
=
0.0527); 305 parameters; 7 restraints; S=1.050; R1 =0.0286 [I>
2s(I)]; wR2 (all data)=0.0694; max/min residual electron density=
[12] Treatment of 1 with an excess of sulfur, selenium, or tellurium
(molar ratio 1:2) resulted also in the formation of 11a–c.
[13] Solution 1H, 13C{1H}, 15N{1H}, 29Si{1H}, 77Se{1H}, and 125Te{1H} NMR
spectra were recorded at 238C on a Bruker Avance 500 NMR spec-
trometer (1H 500.1 MHz; 13C 125.8 MHz; 15N 50.7 MHz; 29Si
99.4 MHz; 77Se 95.4 MHz; 125Te 157.8 MHz). C6D6 was used as the
solvent. Chemical shifts were determined relative to internal
[D5]C6H6 (1H, d=7.28 ppm), internal C6D6 (13C, d=128.0 ppm), ex-
ternal TMS (29Si, d=0 ppm), external formamide (90% w/w in
DMSO; 15N, d=ꢀ268.0 ppm), external Me2Se (5% w/w in C6D6;
77Se, d=0 ppm), or external Ph2Te2 (0.1m in CDCl3; 125Te, d=
422.0 ppm). Assignment of the 13C NMR data was supported by
DEPT 135 and 1H,1H and 1H,13C correlation experiments. Solid-
state 15N, 29Si, and 77Se VACP/MAS NMR spectra and
125Te{1H} HPDec/MAS NMR spectra were recorded at 228C on a
Bruker DSX 400 NMR spectrometer with bottom layer rotors of
ZrO2 (diameter 4 mm (11a) or 7 mm (11b and c) containing about
80 mg (4 mm) or 200 mg (7 mm) of sample (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=
+1.166/ꢀ0.563 eꢃꢀ3
.
[15] For recent publications dealing with higher-coordinate silicon(IV)
compounds, see: a) S. Cota, M. Beyer, R. Bertermann, C. Burschka,
K. Gçtz, M. Kaupp, R. Tacke, Chem. Eur. J. 2010, 16, 6582–6589;
b) S. Metz, B. Theis, C. Burschka, R. Tacke, Chem. Eur. J. 2010, 16,
6844–6856; c) K. Junold, C. Burschka, R. Bertermann, R. Tacke,
Dalton Trans. 2010, 39, 9401–9413; d) K. Junold, C. Burschka, R.
Bertermann, R. Tacke, Dalton Trans. 2011, 40, 9844–9857; e) C.
Kobelt, C. Burschka, R. Bertermann, C. Fonseca Guerra, F. M. Bick-
elhaupt, R. Tacke, Dalton Trans. 2012, 41, 2148–2162; f) K. Junold,
C. Burschka, R. Tacke, Eur. J. Inorg. Chem. 2012, 189–193; g) B.
Theis, J. Weiß, W. P. Lippert, R. Bertermann, C. Burschka, R. Tacke,
Chem. Eur. J. 2012, 18, 2202–2206; h) J. Weiß, B. Theis, S. Metz, C.
Burschka, C. Fonseca Guerra, F. M. Bickelhaupt, R. Tacke, Eur. J.
Inorg. Chem. 2012, 3216–3228.
[16] The Berry distortions were analyzed with PLATON: A. L. Spek,
Acta Crystallogr. Sect. D 2009, 65, 148–155.
ꢀ
[17] For Si X (X=S, Se, Te) bond lengths of five-coordinate silicon(IV)
ꢀ
compounds with equatorial Si X single bonds, see Ref. [15e] and lit-
0 ppm), or Te(OH)6 (
125Te, d=685.5 and 692.2 ppm); spinning rate
erature cited therein.
10 kHz (4 mm) or 7 kHz (7 mm); contact time 3 ms (15N) or 5 ms
(29Si, 77Se); 908 1H transmitter pulse length 2.6 ms (4 mm) or 3.6 ms
(7 mm); repetitions time 4–7 s).
[18] G. M. Sheldrick, Acta. Crystallogr. Sect. A 2008, 64, 112–122.
[14] Crystal structure analyses of 11a, 11b, and 11c·0.7C6H5CH3: Suita-
ble single crystals were mounted in inert oil (perfluoropolyalkyl
ether, ABCR) on a glass fiber and then transferred to the cold nitro-
Received: August 16, 2012
Published online: November 22, 2012
Chem. Eur. J. 2012, 18, 16288 – 16291
ꢂ 2012 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
www.chemeurj.org
16291