Neutral six-coordinate and cationic five-coordinate silicon(IV) complexes with two bidentate monoanionic N, S-pyridine-2-thiolato(-) ligands

Article abstract of DOI:10.1021/ic401698a

A series of neutral six-coordinate silicon(IV) complexes (4-11) with two bidentate monoanionic N,S-pyridine-2-thiolato ligands and two monodentate ligands R¹ and R² was synthesized (4, R¹ = R² = Cl; 5, R¹ = Ph, R² = Cl; 6, R¹ = Ph, R² = F; 7, R¹ = Ph, R² = Br; 8, R ¹ = Ph, R² = N₃; 9, R¹ = Ph, R ² = NCO; 10, R¹ = Ph, R² = NCS; 11, R ¹ = Me, R² = Cl). In addition, the related ionic compound 12 was synthesized, which contains a cationic five-coordinate silicon(IV) complex with two bidentate monoanionic N,S-pyridine-2-thiolato ligands and one phenyl group (counterion: I^-). Compounds 4-12 were characterized by elemental analyses, NMR spectroscopic studies in the solid state and in solution, and crystal structure analyses (except 7). These structural investigations were performed with a special emphasis on the sophisticated stereochemistry of these compounds. These experimental investigations were complemented by computational studies, including bonding analyses based on relativistic density functional theory.

Full text of DOI:10.1021/ic401698a

Article
pubs.acs.org/IC
Neutral Six-Coordinate and Cationic Five-Coordinate Silicon(IV)
Complexes with Two Bidentate Monoanionic N,S‑Pyridine-2-
thiolato(−) Ligands
Johannes A. Baus,† Christian Burschka,† Rudiger Bertermann,† Celia Fonseca Guerra,‡
́
̈
F. Matthias Bickelhaupt,*,‡,§ and Reinhold Tacke*,†
†Institut fur Anorganische Chemie, Universitat Wurzburg, Am Hubland, 97074 Wurzburg, Germany
̈
̈
̈
̈
‡Department of Theoretical Chemistry, Amsterdam Center for Multiscale Modeling (ACMM), VU University Amsterdam,
De Boelelaan 1083, 1081 HV Amsterdam, The Netherlands
§Institute of Molecules and Materials, Radboud University Nijmegen, Heyendaalseweg 135, 6525 AJ Nijmegen, The Netherlands
S
* Supporting Information
ABSTRACT: A series of neutral six-coordinate silicon(IV)
complexes (4−11) with two bidentate monoanionic N,S-
pyridine-2-thiolato ligands and two monodentate ligands R1
and R2 was synthesized (4, R1 = R2 = Cl; 5, R1 = Ph, R2 = Cl; 6,
R1 = Ph, R2 = F; 7, R1 = Ph, R2 = Br; 8, R1 = Ph, R2 = N3; 9, R1
= Ph, R2 = NCO; 10, R1 = Ph, R2 = NCS; 11, R1 = Me, R2 =
Cl). In addition, the related ionic compound 12 was
synthesized, which contains a cationic five-coordinate silicon-
(IV) complex with two bidentate monoanionic N,S-pyridine-2-
thiolato ligands and one phenyl group (counterion: I−).
Compounds 4−12 were characterized by elemental analyses,
NMR spectroscopic studies in the solid state and in solution,
and crystal structure analyses (except 7). These structural
investigations were performed with a special emphasis on the sophisticated stereochemistry of these compounds. These
experimental investigations were complemented by computational studies, including bonding analyses based on relativistic
density functional theory.
the synthesis of compounds 4−12, their NMR spectroscopic
characterization in the solid state and in solution, and their
structural characterization by single-crystal X-ray diffraction
(except 7). The structural characterization of 4−12 was
performed with a special emphasis on the sophisticated
stereochemistry of these compounds (potential existence of
diastereoisomers). These experimental investigations were
complemented by computational studies, which provide
information on the structure and relative stabilities as well as
the bonding mechanism behind the observed and computed
trends of these silicon(IV) complexes.
INTRODUCTION
■
Neutral six-coordinate bis[amidinato(−)]silicon(IV) complexes
with their two highly strained four-membered SiNCN chelate
rings (N−Si−N, 68−70°), such as 1−3, are thermodynamically
stable compounds.1 This finding prompted us to investigate the
synthetic potential of the N,S-pyridine-2-thiolato(−) ligand in
the chemistry of higher-coordinate silicon. Coordination of this
particular monoanionic ligand to silicon in a bidentate fashion
would also result in the formation of a strained four-membered
SiSCN chelate ring [for higher-coordinate silicon(IV) com-
plexes with sulfur and/or pyridine-nitrogen ligand atoms, see
refs 2 and 3]. In the coordination chemistry of transition
metals, the N,S-pyridine-2-thiolato(−) ligand is well estab-
lished,4 but far fewer examples are reported in main-group
chemistry,5−8 with most examples being described for tin(IV).7
Quite surprisingly, silicon(IV) complexes with this N,S-ligand
have not yet been reported. We have now succeeded in
synthesizing compounds 4−11, the first six-coordinate silicon-
(IV) complexes with bidentate N,S-pyridine-2-thiolato(−)
ligands, and the related ionic compound 12, the first five-
coordinate silicon(IV) complex with N,S-pyridine-2-thiolato-
(−) ligands (Scheme 1; for selected reviews on higher-
coordinate silicon compounds, see ref 9). We report here on
RESULTS AND DISCUSSION
■
Syntheses. Compounds 4, 5, and 11 were synthesized
according to Scheme 2 by treatment of the corresponding
chlorosilanes (4, SiCl4; 5, PhSiCl3; 11, MeSiCl3) with 2 mol
equiv each of 2-pyridinethiol and triethylamine in tetrahy-
drofuran (yields: 4, 90%; 5, 98%; 11, 98%). Compounds 6−10
were prepared according to Scheme 3, starting from the
corresponding chlorosilicon(IV) complex 5. The fluorosilicon-
Received: July 4, 2013
© XXXX American Chemical Society
A
dx.doi.org/10.1021/ic401698a | Inorg. Chem. XXXX, XXX, XXX−XXX

Inorganic Chemistry
Article
Scheme 1. Chemical Structures of the Six-Coordinate
Silicon(IV) Complexes 1−11 and the Five-Coordinate
Silicon(IV) Complex 12
Scheme 3. Syntheses of Compounds 6−10
Scheme 4. Synthesis of Compound 12
Scheme 2. Syntheses of Compounds 4, 5, and 11
compound 12 was isolated, which contains a cationic five-
coordiante silicon(IV) complex (Scheme 4; yield 66%).
Compounds 4−12 were isolated after crystallization from
acetonitrile as highly moisture-sensitive crystalline solids. Their
identities were established by elemental analyses (C, H, N, and
S), NMR spectroscopic studies in the solid state (15N, 19F, and
29Si) and in solution (1H, 13C, 19F, and 29Si), and crystal
structure analyses (except 7).
Crystal Structure Analyses. Compounds 4−6 and 8−12
were structurally characterized by single-crystal X-ray diffrac-
tion. All attempts to grow suitable single crystals for a crystal
structure analysis of 7 failed. The crystal data and experimental
parameters used for the crystal structure analyses 4−6 and 8−
12 are given in the Supporting Information (Tables S1 and S2).
The molecular structures of 4−6 and 8−11 are depicted in
Figures 1−8, and the structure of the cation of 12 is shown in
Figure 9. Selected bond lengths and angles are given in the
respective captions.
(IV) complex 6 was obtained by the reaction of 5 with 1 mol
equiv of fluorotrimethylstannane in tetrahydrofuran (yield
84%). The bromosilicon(IV) complex 7 was synthesized by
the treatment of 5 with an excess of bromotrimethylsilane
(yield 68%), and the azidosilicon(IV) complex 8 was obtained
by the reaction of 5 with 1 mol equiv of azidotrimethylsilane
(yield 76%). Both syntheses were performed in acetonitrile.
The synthetic method used for the preparation of 7 and 8 could
not be applied to the syntheses of the analogous (cyanato-
N)silicon(IV) complex 9 and (thiocyanato-N)silicon(IV)
complex 10. Instead, compounds 9 and 10 were prepared by
the treatment of 5 with 1.1 mol equiv of potassium cyanate and
potassium thiocyanate, respectively, in acetonitrile (yields: 9,
88%; 10, 83%). Quite interestingly, the treatment of 5 with
iodotrimethylsilane in acetonitrile did not yield the expected
neutral six-coordinate silicon complex 12′; instead, the ionic
B
dx.doi.org/10.1021/ic401698a | Inorg. Chem. XXXX, XXX, XXX−XXX

Inorganic Chemistry
Article
Figure 3. Molecular structure of diastereomer 5b in the crystal of 5
(occupation factor 87%; probability level of displacement ellipsoids
50%). Selected bond lengths (Å) and angles (deg): Si2−Cl2
2.1924(16), Si2−S3 2.4167(16), Si2−S4 2.3006(17), Si2−N3
1.893(3), Si2−N4 1.948(3), Si2−C31 1.913(3); Cl2−Si2−S3
163.60(8), Cl2−Si2−S4 97.80(7), Cl2−Si2−N3 93.58(14), Cl2−
Si2−N4 90.36(10), Cl2−Si2−C31 96.27(11), S3−Si2−S4 94.91(6),
S3−Si2−N3 71.09(13), S3−Si2−N4 84.01(9), S3−Si2−C31
91.70(11), S4−Si2−N3 157.78(13), S4−Si2−N4 71.02(9), S4−Si2−
C31 99.84(13), N3−Si2−N4 89.96(15), N3−Si2−C31 97.80(17),
N4−Si2−C31 169.43(16). The structure of 5b is disordered
(interchanged positions of Cl2 and S3) with a second molecule
(occupation factor 13%) that represents the antipode of the
enantiomer depicted above. The molecular structures of the two
enantiomers are very similar.
Figure 1. Molecular structure of 4 in the crystal (probability level of
displacement ellipsoids 50%). Selected bond lengths (Å) and angles
(deg): Si−Cl1 2.1648(15), Si−Cl2 2.1897(16), Si−S1 2.2649(13), Si−
S2 2.2697(13), Si−N1 1.949(3), Si−N2 1.949(3); Cl1−Si−Cl2
93.69(6), Cl1−Si−S1 97.73(6), Cl1−Si−S2 93.49(6), Cl1−Si−N1
91.56(10), Cl1−Si−N2 166.01(10), Cl2−Si−S1 92.84(6), Cl2−Si−S2
98.77(6), Cl2−Si−N1 165.21(10), Cl2−Si−N2 89.44(10), S1−Si−S2
163.29(6), S1−Si−N1 72.74(10), S1−Si−N2 95.72(10), S2−Si−N1
94.69(10), S2−Si−N2 72.55(9), N1−Si−N2 88.79(13).
Figure 4. Molecular structure of 6 in the crystal (probability level of
displacement ellipsoids 50%). Selected bond lengths (Å) and angles
(deg): Si−S1 2.4452(11), Si−S2 2.3192(10), Si−F 1.798(2), Si−N1
1.903(2), Si−N2 1.950(3), Si−C11 1.911(4); S1−Si−S2 95.04(4),
S1−Si−F 162.67(8), S2−Si−F 98.39(7), S1−Si−N1 69.95(9), S1−
Si−N2 84.49(8), S1−Si−C11 92.32(10), S2−Si−N1 160.34(8), S2−
Si−N2 71.65(8), S2−Si−C11 96.65(9), F−Si−N1 94.36(11), F−Si−
N2 89.39(10), F−Si−C11 96.92(11), N1−Si−N2 93.69(11), N1−Si−
C11 96.59(12), N2−Si−C11 167.48(12).
Figure 2. Molecular structure of diastereomer 5a in the crystal of 5
(probability level of displacement ellipsoids 50%). Selected bond
lengths (Å) and angles (deg): Si1−Cl1 2.2263(12), Si1−S1
2.3049(13), Si1−S2 2.2980(13), Si1−N1 1.973(3), Si1−N2
1.954(3), Si1−C11 1.906(3); Cl1−Si1−S1 93.90(4), Cl1−Si1−S2
97.18(5), Cl1−Si1−N1 164.07(7), Cl1−Si1−N2 87.06(8), Cl1−Si1−
C11 96.15(10), S1−Si1−S2 160.69(5), S1−Si1−N1 72.04(8), S1−
Si1−N2 92.96(8), S1−Si1−C11 98.69(9), S2−Si1−N1 94.46(8), S2−
Si1−N2 71.95(7), S2−Si1−C11 95.79(9), N1−Si1−N2 86.25(11),
N1−Si1−C11 93.44(12), N2−Si1−C11 167.65(11).
diastereomers 5a (A) and 5b (C); molar ratio 1:1]. In the
case of compounds 4, 6, and 8−11, only one of the four
possible diastereomers is found (4, diastereomer A; 6 and 8−
11, diastereomer C). The positions of the two sulfur ligand
atoms relative to each other make the main difference between
the two structures observed. In the case of compounds 4 and
5a, the sulfur atoms are in trans positions with S−Si−S angles
of 163.29(6)° and 160.69(5)°, respectively. The sulfur atoms in
5b, 6, and 8−11 occupy cis positions [S−Si−S angles,
92.10(4)° to 95.04(4)°], and one of the two sulfur atoms
and the (pseudo)halogeno ligand are in trans positions [S−Si−
R angles (R = Cl, F, N3, NCO, NCS), 161.08(9)−163.57(8)°].
In the latter compounds, the Si−S bonds trans to the
(pseudo)halogeno ligands [2.3944(10)−2.4452(11) Å] are
The silicon-coordination polyhedra of 4−6 and 8−11 are
strongly distorted octahedra, with maximum deviations from
the ideal 90° and 180° angles ranging from 17.45(9)° to
20.05(9)° and from 16.71(6)° to 22.45(8)°, respectively. All of
the structures discussed herein have two chelating monoanionic
N,S-pyridine-2-thiolato ligands in common, which, together
with the silicon-coordination center, build up two highly
strained four-membered SiSCN chelate rings, with S−Si−N
bite angles ranging from 69.95(9)° to 72.55(9)°. As can be seen
from Scheme 5, there are four possible assemblies of these
bidentate ligands (diastereomers A−D), and two of them are
observed in the crystal of 5 [cocrystallization of the
C
dx.doi.org/10.1021/ic401698a | Inorg. Chem. XXXX, XXX, XXX−XXX

Inorganic Chemistry
Article
Figure 5. Molecular structure of 8 in the crystal (probability level of
displacement ellipsoids 50%). Selected bond lengths (Å) and angles
(deg): Si−S1 2.4248(9), Si−S2 2.3060(10), Si−N1 1.908(2), Si−N2
1.949(2), Si−N3 1.885(2), Si−C11 1.902(2), N3−N4 1.076(3), N4−
N5 1.194(4); S1−Si−S2 93.42(3), S1−Si−N1 70.25(7), S1−Si−N2
86.61(7), S1−Si−N3 161.52(9), S1−Si−C11 92.67(8), S2−Si−N1
159.03(7), S2−Si−N2 71.97(7), S2−Si−N3 100.94(8), S2−Si−C11
95.96(9), N1−Si−N2 93.39(9), N1−Si−N3 92.92(10), N1−Si−C11
97.81(11), N2−Si−N3 86.85(9), N2−Si−C11 167.83(11), N3−Si−
C11 97.28(10), Si−N3−N4 128.8(2), N3−N4−N5 175.2(3).
Figure 7. Molecular structure of 10 in the crystal (probability level of
displacement ellipsoids 50%). Selected bond lengths (Å) and angles
(deg): Si−S1 2.3944(10), Si−S2 2.3029(10), S3−C17 1.594(3), Si−
N1 1.897(2), Si−N2 1.940(2), Si−N3 1.829(2), Si−C11 1.905(3),
N3−C17 1.172(3); S1−Si−S2 94.51(4), S1−Si−N1 71.29(7), S1−
Si−N2 88.50(6), S1−Si−N3 163.57(8), S1−Si−C11 94.26(8), S2−
Si−N1 159.69(8), S2−Si−N2 72.06(7), S2−Si−N3 98.54(8), S2−Si−
C11 97.82(8), N1−Si−N2 92.60(9), N1−Si−N3 93.46(10), N1−Si−
C11 97.67(10), N2−Si−N3 86.07(9), N2−Si−C11 169.72(11), N3−
Si−C11 93.82(11), Si−N3−C17 165.0(2), N3−C17−S3 179.6(3).
Figure 8. Molecular structure of 11 in the crystal (occupation factor
83%; probability level of displacement ellipsoids 50%). Selected bond
lengths (Å) and angles (deg): Si−Cl 2.1980(19), Si−S1 2.4088(19),
Si−S2 2.337(3), Si−N1 1.923(3), Si−N2 1.949(3), Si−C1 1.894(4);
Cl−Si−S1 162.69(9), Cl−Si−S2 98.86(12), Cl−Si−N1 93.69(15),
Cl−Si−N2 87.22(11), Cl−Si−C1 95.39(17), S1−Si−S2 93.39(12),
S1−Si−N1 71.01(15), S1−Si−N2 85.12(11), S1−Si−C1 94.73(16),
S2−Si−N1 157.9(2), S2−Si−N2 71.48(13), S2−Si−C1 98.93(17),
N1−Si−N2 91.2(2), N1−Si−C1 97.9(2), N2−Si−C1 170.4(2). The
structure of 11 is disordered (interchanged positions of Cl and S1)
with a second molecule (occupation factor 17%) that represents the
antipode of the enantiomer depicted above. The molecular structures
of the two enantiomers are very similar.
Figure 6. Molecular structure of 9 in the crystal (probability level of
displacement ellipsoids 50%). Selected bond lengths (Å) and angles
(deg): Si−S1 2.4436(11), Si−S2 2.3087(11), Si−N1 1.906(3), Si−N2
1.939(2), Si−N3 1.800(3), Si−C11 1.899(3), O−C17 1.191(4), N3−
C17 1.171(4); S1−Si−S2 92.10(4), S1−Si−N1 70.12(7), S1−Si−N2
86.92(7), S1−Si−N3 162.67(10), S1−Si−C11 92.36(9), S2−Si−N1
157.55(8), S2−Si−N2 71.91(7), S2−Si−N3 101.84(9), S2−Si−C11
96.65(10), N1−Si−N2 92.91(10), N1−Si−N3 93.74(11), N1−Si−
C11 97.65(11), N2−Si−N3 87.68(10), N2−Si−C11 168.49(12),
N3−Si−C11 96.15(12), Si−N3−C17 155.8(3), N3−C17−O
178.1(4).
[1.954(3) and 1.973(3) Å] are identical or differ only slightly,
whereas the two Si−N bond lengths of 5b, 6, and 8−11 differ
by 0.026−0.055 Å. In all cases, the Si−N distances trans to the
sulfur ligand atom [1.890(4)−1.923(3) Å] are shorter than
those trans to the carbon ligand atom [1.939(2)−1.950(3) Å].
The structure of the cation of 12 is characterized by
crystallographic C2 symmetry. The silicon-coordination poly-
hedron is a strongly distorted trigonal bipyramid with the two
nitrogen ligand atoms in the axial positions. The maximum
0.0718−0.1350 Å longer than the Si−S bonds trans to the
nitrogen ligand atom [2.3006(17)−2.337(3) Å]. Generally, the
Si−S bond distances observed for 4−6 and 8−11 are very
similar or slightly longer than those reported for axial Si−S
bonds in five-coordinate2a,c,d,i,m and Si−S bonds in six-
coordinate silicon(IV) complexes.2g,h The Si−N bond lengths
of 4−6 and 8−11 are in the range of 1.890(4)−1.976(4) Å.
The two Si−N distances of 4 [both 1.949(3) Å] and 5a
D
dx.doi.org/10.1021/ic401698a | Inorg. Chem. XXXX, XXX, XXX−XXX

Inorganic Chemistry
Article
NMR Spectroscopic Studies. Compounds 4−12 were
studied by NMR spectroscopy in the solid state (15N, 19F, and
29Si) and (except 4) in solution (1H, 13C, 19F, and 29Si; solvent,
CD2Cl2). The data obtained (see the Experimental Section)
confirm the identities of these compounds.
As can be seen from Table 1, the isotropic 29Si chemical
shifts of 5−11 in the solid state and in solution are very similar,
Table 1. Isotropic 29Si Chemical Shifts (ppm) of 4−12 in the
Solid State (T = 22 °C) and in Solution (T = 23 °C; Solvent,
CD2Cl2)
compound
δ29Si (solid state)
δ29Si (solution)
4
−182.2 to −177.4
a
b
5
−156.9 to −153.4, −152.9 to −149.0
−154.1
−149.0
c
d
6
−150.2
Figure 9. Molecular structure of the cation in the crystal of 12
(probability level of displacement ellipsoids 50%). Selected bond
lengths (Å) and angles (deg): Si−S1 2.180(2), Si−S1A 2.180(2), Si−
N1 1.944(4), Si−N1A 1.944(4), Si−C6 1.848(10); S1−Si−S1A
117.77(16), S1−Si−N1 74.69(14), S1−Si−N1A 94.81(15), S1−Si−
C6 121.11(8), S1A−Si−N1 94.81(15), S1A−Si−N1A 74.69(14),
S1A−Si−C6 121.11(8), N1−Si−N1A 159.9(3), N1−Si−C6
100.04(17), N1A−Si−C6 100.04(17).
b
7
−167.8 to −160.0
−164.4
−153.9
−163.7
−168.7
−148.3
8
−156.2
−165.5
−170.3
−150.1 to −149.4
−76.5
9
10
11
12
b
e
−77.2
a
b
Insoluble in common deuterated organic solvents. Multiplet due to
c
d
dipolar coupling. Doublet, 1J(29Si,19F) = 268 Hz. Doublet,
Scheme 5. Four Possible Diastereomers (A−D) of
Compounds 4−11
e
1J(29Si,19F) = 275 Hz. Spectrum recorded at −70 °C.
indicating that the six-coordinate silicon(IV) complexes exist
also in solution. This assumption is further supported by all of
the other NMR spectroscopic data obtained (see the
Experimental Section). The isotropic 29Si chemical shifts of
12 in the solid state and in solution are also very similar (Table
1), indicating that the five-coordinate silicon(IV) complex 12
exists in solution as well. Compound 5 shows two 29Si
resonance signals in the solid state, which is in agreement with
the results of the crystal structure analysis (cocrystallization of
the two diastereomers 5a and 5b). NMR spectroscopic data for
compound 4 in solution could not be obtained because of its
poor solubility in common deuterated organic solvents. The
29Si NMR spectrum of 12 in solution was recorded at −70 °C
because of its strongly pronounced dynamic behavior at 23 °C
(no signal detected at 23 °C). The range of the isotropic 29Si
chemical shifts of 4−11 indicates a strong influence of the
different monodentate ligands on the 29Si chemical shift. As can
be seen from the similar isotropic 29Si chemical shifts of the two
diastereomers 5a and 5b in the solid state, the different relative
arrangements of the two sulfur ligand atoms (5a, trans; 5b, cis)
only slightly affect the 29Si chemical shift.
deviations from the ideal 90°, 120°, and 180° angles amount to
15.31(14)°, 2.23(16)°, and 20.1(3)°, respectively. The sum of
the equatorial bond angles is 360.0°, and the Berry distortion10
amounts to 21.9%. The two chelating N,S-pyridine-2-thiolato
ligands and the silicon-coordination center build up two highly
strained four-membered SiSCN chelate rings, with S−Si−N
bite angles of 74.69(14)°. This value, however, is somewhat
higher than those observed for the six-coordinate silicon(IV)
complexes 4−6 and 8−11 [69.95(9)−72.55(9)°]. The two Si−
S bond distances of 12 [both 2.180(2) Å] are significantly
shorter than those observed for 4−6 and 8−11 [2.3006(17)−
2.337(3) and 2.3944(10)−2.4451(11) Å] but very similar to
those reported for equatorial Si−S bonds in five-coordinate
silicon(IV) complexes.2a,c−e,i,l,m The two Si−N bond distances
of 12 [both 1.994(4) Å] are somewhat longer than those
observed for 4−6 and 8−11 [1.890(4)−1.976(4) Å].
A comparison of the isotropic 15N chemical shifts of
compounds 4−12 in the solid state shows that the two
pyridine-nitrogen atoms of 4−11 differ from each other (Table
2). For the more symmetrical dichloro complex 4, the shift
difference is relatively small (3.0 ppm), whereas the shift
differences for 5−11 are much larger (Δδ29Si = 23.6−27.6
ppm). For the C2-symmetrical silicon(IV) complex 12, only
one 15N resonance signal for the two pyridine-nitrogen atoms
was observed. Contrary to the solid-state 29Si NMR spectrum
of 5 (two resonance signals), the 15N NMR spectrum of 5 does
not show separate resonance signals for the two diastereomers
(only two out of four expected resonance signals were
observed).11 The isotropic 15N chemical shifts of the nitrogen
atoms of the cyanato-N, thiocyanato-N, or azido ligands of 8−
10 are within the expected ranges.
E
dx.doi.org/10.1021/ic401698a | Inorg. Chem. XXXX, XXX, XXX−XXX

Inorganic Chemistry
Article
Table 2. Isotropic 15N Chemical Shifts (ppm) of 4−12 in the
Solid State (T = 22 °C)
stereochemistry of 5 in solution (solvent, CD2Cl2), variable-
temperature NMR studies were performed. Upon cooling from
23 to −70 °C, the 29Si resonance signal splits into two signals
(−156.4 and −155.4 ppm; intensity ratio ca. 4:1; Figure 11),
δ15N (pyridine-2-
compound
thiolato ligands)
δ15N (pseudohalogeno ligand)
4
5
6
7
8
−110.7, −107.7
−133.8, −110.2
−135.7, −109.6
−133.5, −109.1
−135.5, −107.9
−303.2 (NNN), −208.4 (NNN),
−138.4 (NNN)
9
−134.8, −110.0
−136.0, −110.7
−129.8, −104.5
−126.6
−325.7 (NCO)
−233.9 (NCS)
10
11
12
Figure 11. Temperature dependence of the 29Si NMR spectrum of 5
(CD2Cl2; 99.4 MHz). The temperature dependence of the 29Si NMR
spectrum is completely reversible upon heating.
indicating the existence of two diastereomers that are
configurationally stable on the NMR time scale at this
temperature. Figure 12 shows the temperature dependence of
1
the H NMR spectrum of 5 in the temperature range of 23 to
−70 °C (solvent, CD2Cl2), indicating a dynamic behavior,
which can be interpreted in terms of an isomerization process
(interconversion of the diastereomers 5a and 5b). At −70 °C,
1
there are also two sets of resonance signals in the H NMR
spectrum (intensity ratio 4:1; Figures 12 and 13), again
indicating the existence of two diastereomers. This result is in
agreement with that obtained in the low-temperature 29Si NMR
studies of 5 (see above). On the basis of the results of
quantum-chemical investigations (see the Computational
Studies section), the dominating species can be assigned to
isomer C (5b) and the other species to isomer A (5a).
As observed for 5, the H, 13C, and 29Si NMR spectra of 6−
1
11 show only one set of resonance signals each at 23 °C
Figure 10. 29Si VACP/MAS NMR spectra of (A) 4, (B) 5, and (C) 11
(νrot = 10 kHz; T = 22 °C) and (D) the 29Si HPDec/MAS NMR
spectrum of 7 (νrot = 6.8 kHz; T = 22 °C).
1
(solvent, CD2Cl2), whereas two sets of H resonance signals
1
were observed at −70 °C (except for 11; only one set of H
resonance signals) with intensity ratios of about 18:1 (6), 1.2:1
(7), 8:1 (8), 17:1 (9), or 3:1 (10) (intensity ratios extracted
from the 1H NMR spectra). The interpretation of these
findings is analogous to that given for 5. In the 1H, 13C, and 29Si
NMR spectra of the ionic compound 12, only one set of
resonance signals each was observed at −70 °C.
Computational Studies. To further support and ration-
alize the experimental findings obtained in the crystal structure
analyses and NMR spectroscopic studies of 5−10 and 12, we
have conducted theoretical analyses of the structure, stability,
and bonding of various silicon(IV) complexes Si-
(SC5H4N)2PhX with X = F, Cl, Br, I, N3, NCO, and NCS in
the gas phase and in a dichloromethane solution using
relativistic density functional theory (DFT).
As shown in Figure 10, the resonance signals in the solid-
state 29Si NMR spectra of the chlorosilicon(IV) complexes 4, 5,
and 11 and the bromosilicon(IV) complex 7 are broadened
because of J(29Si,X) couplings [X = 35Cl (I = /2), 37Cl (I =
3/2); 79Br (I = 3/2), 81Br (I = 3/2)]. In addition, it is well-known
that magic angle spinning (MAS) fails to eliminate the effect of
dipolar coupling for spin 1/2 nuclei completely when coupled to
quadrupole nuclei with a quadrupole frequency comparable to
the Zeeman frequency of the nuclei.12 The spectrum of 5 shows
two resonance signals (intensity ratio 1:1) due to the presence
of two diastereomers.
1
3
The 29Si NMR spectrum of compound 5 in solution (solvent,
CD2Cl2) shows one resonance signal at 23 °C (−154.1 ppm),
whereas the solid-state NMR studies and the crystal structure
analysis revealed the existence of two diastereomers in the
crystal (molar ratio 1:1). To get more information about the
All calculations were performed with the Amsterdam Density
Functional (ADF) program,13 using relativistic DFT at ZORA-
BP86/TZ2P for geometry optimization and energies.14,15
Solvation in dichloromethane was simulated using the
F
dx.doi.org/10.1021/ic401698a | Inorg. Chem. XXXX, XXX, XXX−XXX

Inorganic Chemistry
Article
1
Figure 12. Temperature dependence of the H NMR spectrum of 5 in the temperature range of 23 to −70 °C (CD2Cl2; 500.1 MHz). The
1
temperature dependence of the H NMR spectrum is completely reversible upon heating (the asterisk indicates the broad resonance signal of the
pyridine H-6 protons at ca. 8.15 ppm).
of X = N3 (Figure 15). In all cases, isomers A and C are more
stable than B and D. Here, we are mainly interested in the
relative stability of A with respect to C as a function of ligand X.
The computations confirm the experimental observation that
for compounds 5−10 two diastereomers are observed in
solution (CD2Cl2) at −70 °C, one of which is dominating.
According to the calculated relative energies, these species are
the diastereomers A and C, with C being the dominating one
(Figures 14 and 15). Furthermore, the results of the
computational studies are also in agreement with the
experimental observation that the diastereomers of 5 (5a,
type A; 5b, type C) cocrystallize; in fact, the calculated energy
difference between A and C (0.8 kcal mol−1) is very small and
1
Figure 13. Partial H NMR spectrum of 5 at −70 °C (CD2Cl2; 500.1
represents the smallest one in the series of compounds studied
experimentally by single-crystal X-ray diffraction. In the case of
6 and 8−10 (energy difference between A and C, 1.6−2.8 kcal
mol−1), only diastereomer C was observed in the crystal.
The computational studies, furthermore, show that, for the
silicon(IV) complexes with X = F, Cl, Br, and I, the viability of
diastereomer A further increases upon going from X = F to I. In
the case of the not yet synthesized complex with X = I [we
rather isolated the five-coordinate ionic silicon(IV) complex
12], diastereomer A is even slightly more favorable than C.
Thus, the relative stabilities of A relative to C are 1.7 (F), 0.8
(Cl), 0.2 (Br), and −0.3 kcal mol−1 (I), respectively (Figure
14). Note that for all ligands X, except X = I, C is the most
stable diastereomer. In the case of the three pseudohalogeno
ligands coordinating via a nitrogen atom (X = N3, NCO, NCS),
diastereomer A is destabilized relative to C by 1.6−2.8 kcal
mol−1 (Figure 15), that is, by an amount similar to that in the
case of X = F or even more.
MHz), showing the resonance signals of two protons of each of the
two diastereomers (molar ratio 4:1).
conductor-like screening model (COSMO).16 All stationary
points were verified to be minima on the potential energy
surface through vibrational analysis. The bonding mechanism
was analyzed within the framework of quantitative Kohn−Sham
molecular orbital (MO) theory in combination with a
quantitative energy decomposition analysis (EDA) of the
interaction energy ΔEint of selected bonds into classical
electrostatic attraction ΔVelstat, Pauli repulsion ΔEPauli between
occupied orbitals, and stabilizing orbital interactions ΔEoi, such
as highest occupied molecular orbital (HOMO)−lowest
unoccupied molecular orbital (LUMO) interaction (for details,
see ref 17). Atomic charges were computed using the Voronoi
Deformation Density (VDD) method developed by Bick-
elhaupt et al.18
The computed structures and relative energies of the four
diastereomers A−D of the studied silicon(IV) complexes
Si(SC5H4N)2PhX in CH2Cl2 are collected in Figures 14 and
15. The four diastereomers have, for each X, stabilities with a
maximum span in relative energies of 6.4 kcal mol−1 in the case
The Si−X bond distance in diastereomer C increases from
ca. 1.68 to 2.71 Å along X = F, Cl, Br, and I (Figure 14), and
the Si−N bond distance in the three compounds with ligands
coordinating via a nitrogen atom (X = N3, NCO, NCS)
G
dx.doi.org/10.1021/ic401698a | Inorg. Chem. XXXX, XXX, XXX−XXX

Inorganic Chemistry
Article
Figure 14. Relative energies (kcal mol−1) and bond lengths (Å) of the isomers A−D of the silicon(IV) complexes Si(SC5H4N)2PhX (X = F, Cl, Br,
I), computed at ZORA-BP86/TZ2P with COSMO for simulating solvation in CH2Cl2.
amounts to 1.80−1.85 Å (Figure 15). For a given ligand X, the
variation in the Si−X bond distance along the isomers A−D is
relatively small, between 0.01 Å for X = F and 0.05 Å for X = I
with its weaker and softer Si−I bond. The silicon−element
bonds to the N,S-pyridine-2-thiolato and phenyl ligands are
relatively constant in all complexes (diastereomers A−D), with
values of 1.91−1.93 Å for Si−C and 1.92−2.02 Å for Si−N and
a somewhat larger range for Si−S (2.33−2.52 Å; Figures 14 and
15). Generally, the calculated silicon−element bond distances
of diastereomers A and C are in reasonable agreement with the
experimental data obtained in the crystal structure analyses of 5,
6, and 8−10 (Figures 2−7).
The above trend in the relative stability between
diastereomers A and C is clear yet also subtle because it refers
to differences in energy of about a few to only a few tenths of a
kilocalorie per mole. We have, nevertheless, tried to shed light
on its origin through analysis of the Si−X bond between
Si(SC5H4N)2Ph+ and X− in eight representative model systems,
diastereomers A and C for the cases with X = F, Cl, Br, and I, in
the gas phase using quantitative Kohn−Sham MO theory in
combination with a bond EDA. Heterolytic dissociation of X−
from either A or B yields the cation AB, whereas from either C
or D, this yields the cation CD (Scheme 6 and Figure 16). Both
cationic species have a distorted square-pyramidal structure.
Interestingly, cation AB is 6.5 kcal mol−1 more stable than
CD. This order in stability is inverted only after formation of
the Si−X bond, which is substantially stronger for X−
interacting with CD than with AB (Table 3). For example,
the Si−F bond strength between CD and F− is −169.3 kcal
mol−1, while between AB and F−, it amounts to only −161.6
kcal mol−1. This leads to inversion from −6.5 kcal mol−1 in
favor of AB relative to CD to +1.3 kcal mol−1 against A relative
to C in the gas phase, as shown in Figure S1 in the Supporting
Information (in CH2Cl2; this value is 1.7 kcal mol−1 against A
relative to C; Figure 14). EDA in Table 3 shows that the Si−F
bond in C is stronger than that in A because of somewhat less
steric (Pauli) repulsion ΔEPauli and a more favorable electro-
static attraction term ΔVelstat. This suggests that there is slightly
less steric congestion in C than in A, a subtle effect that is not
easily revealed by simple inspection of the structures in Figures
2, 3, and 14.
The fact that, along X = F, Cl, Br, and I, the energy of A
decreases relative to that of C can be understood in terms of
the decreasing Si−X bond strength. This has the consequence
that, while the Si−X bond always remains stronger in C, the
absolute difference in the Si−X bond strengths between A and
C becomes smaller and, for X = I, can no longer invert the
stability order between AB and CD, which is 6.5 kcal mol−1 in
favor of the former. The heterolytic Si−X bond strength
decreases along the anionic halogeno ligands because the
electron-donating capability of their valence p atomic orbital
decreases along X = F, Cl, Br, and I. This trend is reinforced by
H
dx.doi.org/10.1021/ic401698a | Inorg. Chem. XXXX, XXX, XXX−XXX

Inorganic Chemistry
Article
Figure 15. Relative energies (kcal mol−1) and bond lengths (Å) of the isomers A−D of the silicon(IV) complexes Si(SC5H4N)2PhX (X = N3, NCO,
NCS), computed at ZORA-BP86/TZ2P with COSMO for simulating solvation in CH2Cl2.
Scheme 6. Isomers AB and CD of the Cation
Si(SC5H4N)2Ph+
Table 3. Si−X Bond EDA (kcal mol−1) and Silicon Atomic
Charges (au) of Diastereomers A and C of the Silicon(IV)
Complexes Si(SC5H4N)2PhX (X = F, Cl, Br, I) in the Gas
a
Phase
F
Cl
Br
I
A
ΔEbond
ΔEprep
−161.6
37.1
−107.9
37.4
−96.2
36.4
−85.7
35.1
ΔEint
ΔEPauli
−198.7
202.3
−145.3
152.7
−132.6
137.1
−120.8
117.5
ΔVelstat
ΔEoi
Q(Si) in cation AB′
ΔEbond
ΔEprep
−257.6
−143.4
+0.363
−169.3
37.7
−180.7
−117.3
+0.364
−115.2
36.8
−163.7
−105.9
+0.363
−103.2
35.5
−143.7
−94.5
+0.362
−92.3
33.2
C
ΔEint
ΔEPauli
−207.0
199.0
−152.0
151.1
−138.7
135.2
−125.5
117.1
ΔVelstat
ΔEoi
Q(Si) in cation CD′
−265.2
−140.8
+0.351
−188.9
−114.2
+0.351
−171.0
−102.9
+0.350
−150.9
−91.7
+0.348
a
Computed at ZORA-BP86/TZ2P (structures and energies) in the
gas phase. EDA: ΔEbond = ΔEprep + ΔEint and ΔEint = ΔEPauli + ΔVelstat
+ ΔEoi. Q(Si) = VDD atomic charge of silicon in AB′ or CD′, that is,
those cationic fragments in the geometry they adopt in the overall
molecules A and C, respectively.
a weakening in the electrostatic attraction in the same order
because of increasing Si−X bond distance as one goes from X =
F to I. This has been discussed in more detail in earlier work, in
which it was shown that for exactly the same reason the gas-
phase proton affinity,19 alkyl cation affinity,20 and nucleophil-
icity decrease in the very same order.21 The fact that the
attempted synthesis of 12′ instead yields 12 is consistent with
the computational result that 12′ contains by far the weakest
silicon−halogen bond in the series studied.
Figure 16. Side and top views of cations AB (resulting from removal
of X− from A or B) and CD (resulting from removal of X− from C or
D) computed at ZORA-BP86/TZ2P in the gas phase. Cation AB is 6.5
kcal mol−1 more stable than CD.
I
dx.doi.org/10.1021/ic401698a | Inorg. Chem. XXXX, XXX, XXX−XXX

Inorganic Chemistry
Article
Finally, we recall that our computations predict that the
relative abundance of the Si(SC5H4N)2PhX diastereomer A
relative to C further increases if one proceeds from X = F to Cl
and Br and to the not yet synthesized species with X = I. For X
= I, diastereomer A is even more stable than C. As an
approximate indicator of these species’ kinetic stabilities toward
decomposition through bimolecular processes, we have
computed the HOMO−LUMO gap in all silicon(IV)
complexes Si(SC5H4N)2PhX (X = F, Cl, Br, I, N3, NCO,
NCS) both in the gas phase and in CH2Cl2 (Table 4). It
on the basis of the heterolytic silicon−(pseudo)halogeno bond
strength.
EXPERIMENTAL SECTION
■
General Procedures. All syntheses were carried out under a dry
argon atmosphere in oven-dried glassware using standard Schlenk
techniques. The organic solvents used were dried and purified
according to standard procedures. Solution 1H, 13C{1H}, 19F{1H}, and
29Si{1H} NMR spectra were recorded at 23 °C (if not specified
otherwise) on a Bruker Avance 500 (1H, 500.1 MHz; 13C, 125.8 MHz;
29Si, 99.4 MHz), Bruker Avance 400 (19F, 376.5 MHz), or Bruker
DRX-300 (1H, 300.1 MHz; 13C, 75.5 MHz; 29Si, 59.6 MHz) NMR
spectrometer. CD2Cl2 was used as the solvent. Chemical shifts (ppm)
were determined relative to internal CDHCl2 (1H, δ 5.32), internal
CD2Cl2 (13C, δ 53.8), external CFCl3 (19F, δ 0), or external
Table 4. HOMO−LUMO Gap (eV) of Diastereomers A−D
of the Silicon(IV) Complexes Si(SC5H4N)2PhX (X = F, Cl,
a
Br, I, N3, NCO, NCS) in the Gas Phase and in CH2Cl2
1
tetramethylsilane (29Si, δ 0). Assignment of the H and 13C NMR
X
A
B
C
D
data was supported by 1H−1H and 1H−13C correlation and DEPT 135
experiments. The thermocouple used with the probe for the variable-
temperature NMR studies was calibrated for lower temperatures
according to ref 22 using a 4% solution of MeOH in [D4]MeOH
containing a trace of HCl. Solid-state 15N and 29Si VACP/MAS, 29Si
HPDec/MAS, and 19F MAS NMR spectra were recorded at 22 °C on
a Bruker DSX-400 NMR spectrometer with bottom layer rotors of
ZrO2 (diameter, 4 or 7 mm) containing ca. 50 mg (4 mm) or ca. 250
mg (7 mm) of sample [15N, 40.6 MHz; 19F, 376.5 MHz; 29Si, 79.5
MHz; external standard, tetramethylsilane (29Si, δ 0), glycine (15N, δ
−342.0), or CaF2 (19F, δ −108.0); spinning rate, 10 kHz (VACP/
MAS), 6.8 kHz (HPDec/MAS), or 15 kHz (MAS); contact time, 5 ms
gas phase
F
2.78
2.77
2.69
2.32
2.69
2.78
2.51
2.95
2.95
2.93
2.81
2.93
2.95
2.93
2.41
2.36
2.35
2.24
2.41
2.40
2.36
2.61
2.58
2.58
2.52
2.57
2.56
2.58
2.62
2.62
2.62
2.55
2.62
2.60
2.60
2.85
2.85
2.86
2.83
2.84
2.81
2.82
2.59
2.57
2.49
2.23
2.63
2.61
2.50
2.81
2.79
2.74
2.60
2.82
2.80
2.78
Cl
Br
I
N3
NCO
NCS
F
CH2Cl2
Cl
Br
I
1
(15N, 29Si); 90° H transmitter pulse length, 2.6 μs (4 mm) or 3.6 μs
N3
NCO
NCS
(7 mm); repetition time, 5−15 s, depending on the relaxation times of
the protons].
Dichlorobis[N,S-pyridine-2-thiolato(−)]silicon(IV) (4). Tri-
ethylamine (1.79 g, 17.7 mmol) and tetrachlorosilane (1.50 g, 8.83
mmol) were added at 20 °C in single portions one after another to a
stirred solution of 2-pyridinethiol (1.96 g, 17.6 mmol) in
tetrahydrofuran (40 mL), and the reaction mixture was then stirred
at this temperature for 16 h. The resulting precipitate was filtered off,
washed with tetrahydrofuran (2 × 10 mL), and discarded. The solvent
of the filtrate (including the wash solutions) was removed in vacuo,
followed by the addition of acetonitrile (25 mL). The resulting
suspension was heated until a clear solution was obtained, which was
then cooled slowly to 20 °C and kept undisturbed at this temperature
for 2 days. The resulting colorless crystalline solid was isolated by
filtration, washed with n-pentane (2 × 5 mL), and dried in vacuo (20
°C, 4 h, 0.01 mbar). Yield: 2.53 g (7.92 mmol, 90%). 15N VACP/MAS
NMR: δ −110.7, −107.7. 29Si VACP/MAS NMR: δ −182.2 to
−177.4. Anal. Calcd for C10H8Cl2N2S2Si (319.31): C, 37.62; H, 2.53;
N, 8.77; S, 20.08. Found: C, 37.5; H, 2.6; N, 8.7; S, 19.6.
Chlorophenylbis[N,S-pyridine-2-thiolato(−)]silicon(IV) (5).
Triethylamine (1.44 g, 14.2 mmol) and trichlorophenylsilane (1.50
g, 7.09 mmol) were added at 20 °C in single portions one after
another to a stirred solution of 2-pyridinethiol (1.58 g, 14.2 mmol) in
tetrahydrofuran (30 mL), and the reaction mixture was then stirred at
this temperature for 16 h. The resulting precipitate was filtered off,
washed with tetrahydrofuran (2 × 10 mL), and discarded. The solvent
of the filtrate (including the wash solutions) was removed in vacuo,
followed by the addition of acetonitrile (12 mL). The resulting
suspension was heated until a clear solution was obtained, which was
then cooled slowly to 20 °C and kept undisturbed at this temperature
for 2 days. The resulting colorless crystalline solid was isolated by
filtration, washed sequentially with diethyl ether (2 × 10 mL) and n-
pentane (2 × 5 mL), and dried in vacuo (20 °C, 4 h, 0.01 mbar).
Yield: 2.50 g (6.93 mmol, 98%). 1H NMR (500.1 MHz): δ 7.07−7.09
(m, 2 H; H-5, SC5H4N), 7.17−7.24 (m, 3 H; H-3/H-4/H-5, C6H5),
7.44−7.46 (m, 2 H; H-3, SC5H4N), 7.63−7.65 (m, 2 H; H-2/H-6,
C6H5), 7.70−7.74 (m, 2 H; H-4, SC5H4N), 8.14 (br s, 2 H; H-6,
SC5H4N). 13C{1H} NMR (75.5 MHz): δ 118.1 (C-5, SC5H4N), 125.5
(C-3, SC5H4N), 127.3 (C-3/C-5, C6H5), 127.8 (C-4, C6H5), 132.6 (C-
2/C-6, C6H5), 140.8 (C-6, SC5H4N), 141.3 (C-4, SC5H4N), 152.7 (C-
a
Computed at ZORA-BP86/TZ2P (structures and energies) in the
gas phase and solvated in CH2Cl2 (COSMO).
appears that the HOMO−LUMO gap of isomer C is essentially
equal for all X, i.e., ca. 2.8−2.9 eV in CH2Cl2. Also for
diastereomer A, the HOMO−LUMO gap decreases only
slightly from 3.0 eV (X = F, Cl) via 2.9 eV (X = Br) to 2.8
eV (X = I).
CONCLUSION
■
With the synthesis of compounds 4−11, a series of novel
neutral six-coordinate silicon(IV) complexes with SiS2N2Cl2,
SiS2N2FC, SiS2N2ClC, SiS2N2BrC, and SiS2N3C skeletons has
been made available. Compound 12 represents a novel cationic
five-coordinate silicon(IV) complex with a SiS2N2C skeleton.
To the best of our knowledge, compounds 4−12 are the first
silicon(IV) complexes with bidentate monoanionic N,S-
pyridine-2-thiolato(−) ligands. Compounds 5−12 exist both
in the solid state and in solution, whereas 4 could only be
studied in the solid state because of its poor solubility. In the
case of 5, two diastereomers (5a and 5b) cocrystallize (molar
ratio 1:1). The silicon-coordination polyhedra of 4−6 and 8−
11 in the crystal are best described as strongly distorted
octahedra, with the two sulfur atoms in trans (4 and
diastereomer 5a) or cis position (diastereomer 5b, 6, and 8−
11). The silicon-coordination polyhedron of 12 is a strongly
distorted trigonal bipyramid with the two nitrogen ligand atoms
in the axial sites. The experimental results are supported and
explained by our quantum-chemical computations and bonding
analyses based on relativistic DFT. Experimental and computed
structures agree well. The computations reveal that trends in
product distributions (diastereomers of 5−10 and the
formation of 12 instead of the targeted 12′) can be understood
J
dx.doi.org/10.1021/ic401698a | Inorg. Chem. XXXX, XXX, XXX−XXX

Inorganic Chemistry
Article
1, C6H5), 167.5 (C-2, SC5H4N). 29Si{1H} NMR (99.4 MHz): δ
−154.1. 15N VACP/MAS NMR: δ −133.8, −110.2. 29Si VACP/MAS
NMR: δ −156.9 to −153.4, −152.9 to −149.0. Anal. Calcd for
C16H13ClN2S2Si (360.96): C, 53.24; H, 3.63; N, 7.76; S, 17.77. Found:
C, 53.1; H, 3.6; N, 7.8; S, 17.6.
MHz): δ 117.9 (C-5, SC5H4N), 125.7 (C-3, SC5H4N), 127.5 (C-3/C-
5, C6H5), 128.0 (C-4, C6H5), 133.2 (C-2/C-6, C6H5), 140.9 (C-6,
SC5H4N), 141.1 (C-4, SC5H4N), 149.2 (C-1, C6H5), 168.1 (C-2,
SC5H4N). 29Si{1H} NMR (59.6 MHz): δ −153.9. 15N VACP/MAS
NMR: δ −303.2 (NNN), −208.4 (NNN), −138.4 (NNN), −135.5
(SC5H4N), −107.9 (SC5H4N). 29Si VACP/MAS NMR: δ −156.2.
Anal. Calcd for C16H13N5S2Si (367.53): C, 52.29; H, 3.57; N, 19.06; S,
17.45. Found: C, 52.3; H, 3.5; N, 18.7; S, 17.3.
Fluorophenylbis[N,S-pyridine-2-thiolato(−)]silicon(IV) (6).
Fluorotrimethylstannane (977 mg, 5.34 mmol) was added at 20 °C
in a single portion to a stirred solution of 5 (1.93 g, 5.35 mmol) in
tetrahydrofuran (40 mL), and the reaction mixture was then stirred at
this temperature for 2 h. The resulting precipitate was filtered off,
washed with tetrahydrofuran (2 × 10 mL), and discarded, and the
solvent of the filtrate (including the wash solutions) was removed in
vacuo, followed by the addition of acetonitrile (35 mL). The resulting
suspension was heated until a clear solution was obtained, which was
then cooled slowly to 20 °C and kept undisturbed at this temperature
for 2 days. The resulting colorless crystalline solid was isolated by
filtration, washed sequentially with diethyl ether (2 × 10 mL) and n-
pentane (2 × 5 mL), and dried in vacuo (20 °C, 4 h, 0.01 mbar).
Yield: 1.54 g (4.47 mmol, 84%). 1H NMR (500.1 MHz): δ 7.01−7.10
(m, 2 H; H-5, SC5H4N), 7.18−7.26 (m, 3 H; H-3/H-4/H-5, C6H5),
7.38−7.46 (m, 2 H; H-3, SC5H4N), 7.66−7.73 (m, 4 H; H-2/H-6,
C6H5, and H-4, SC5H4N), 7.79 (br s, 2 H; H-6, SC5H4N). 13C{1H}
NMR (125.8 MHz): δ 117.7 (C-5, SC5H4N), 125.7 (C-3, SC5H4N),
127.3 (C-3/C-5, C6H5), 128.0 (C-4, C6H5), 133.4 (C-2/C-6, C6H5),
140.9 (C-6, SC5H4N), 141.3 (C-4, SC5H4N), 150.1 (C-1, C6H5), 168.9
(C-2, SC5H4N). 19F{1H} NMR (376.5 MHz): δ −131.4 (br s; fwhh =
970 Hz). 29Si{1H} NMR (99.4 MHz): δ −149.0 (d, 1J(29Si,19F) = 275
Hz). 15N VACP/MAS NMR: δ −135.7, −109.6. 19F MAS NMR: δ
(Cyanato-N)phenylbis[N,S-pyridine-2-thiolato(−)]silicon(IV)
(9). Potassium cyanate (195 mg, 2.40 mmol) was added at 20 °C in a
single portion to a stirred solution of 5 (790 mg, 2.19 mmol) in
acetonitrile (30 mL), and the reaction mixture was then stirred at this
temperature for 3 days. The solvent was removed in vacuo, and
dichloromethane (40 mL) was added to the residue. The resulting
precipitate was filtered off, washed with dichloromethane (2 × 10 mL),
and discarded, and the solvent of the filtrate (including the wash
solutions) was removed in vacuo, followed by the addition of
acetonitrile (15 mL). The resulting suspension was heated until a clear
solution was obtained, which was then cooled slowly to 20 °C and
kept undisturbed at this temperature for 2 days. The resulting colorless
crystalline solid was isolated by filtration, washed sequentially with
diethyl ether (2 × 10 mL) and n-pentane (2 × 5 mL), and dried in
1
vacuo (20 °C, 4 h, 0.01 mbar). Yield: 710 mg (1.93 mmol, 88%). H
NMR (500.1 MHz): δ 7.05−7.07 (m, 2 H; H-5, SC5H4N), 7.19−7.27
(m, 3 H; H-3/H-4/H-5, C6H5), 7.42−7.44 (m, 2 H; H-3, SC5H4N),
7.64−7.67 (m, 2 H; H-2/H-6, C6H5), 7.69−7.72 (m, 2 H; H-4,
SC5H4N), 7.89 (br s, 2 H; H-6, SC5H4N). 13C{1H} NMR (125.8
MHz): δ 117.9 (C-5, SC5H4N), 125.9 (C-3, SC5H4N), 127.4 (C-3/C-
5, C6H5), 127.9 (C-4, C6H5), 132.9 (C-2/C-6, C6H5), 140.4 (C-6,
SC5H4N), 141.0 (C-4, SC5H4N), 151.3 (C-1, C6H5), 168.4 (C-2,
SC5H4N). 29Si{1H} NMR (99.4 MHz): δ −163.7. 15N VACP/MAS
NMR: δ −325.7 (NCO), −134.8 (SC5H4N), −110.0 (SC5H4N). 29Si
VACP/MAS NMR: δ −165.5. Anal. Calcd for C17H13N3OS2Si
(367.53): C, 55.56; H, 3.57; N, 11.43; S, 17.45. Found: C, 55.5; H,
3.5; N, 11.5; S, 17.4.
1
−139.4. 29Si VACP/MAS NMR: δ −150.2 (d, J(29Si,19F) = 268 Hz).
Anal. Calcd for C16H13FN2S2Si (344.51): C, 55.78; H, 3.80; N, 8.13; S,
18.62. Found: C, 55.3; H, 3.9; N, 8.1; S, 18.6.
Bromophenylbis[N,S-pyridine-2-thiolato(−)]silicon(IV) (7).
Bromotrimethylsilane (1.06 g, 6.92 mmol) was added at 20 °C in a
single portion to a stirred solution of 5 (1.00 g, 2.77 mmol) in
acetonitrile (30 mL), and the reaction mixture was then stirred at 65
°C for 3 h and at 20 °C for 3 days. The solvent and the generated
chlorotrimethylsilane were removed in vacuo, followed by the addition
of acetonitrile (20 mL). The resulting suspension was heated until a
clear solution was obtained, which was then cooled slowly to 20 °C
and kept undisturbed at this temperature for 2 days. The resulting
colorless crystalline solid was isolated by filtration, washed sequentially
with diethyl ether (2 × 10 mL) and n-pentane (2 × 5 mL), and dried
in vacuo (20 °C, 4 h, 0.01 mbar). Yield: 770 mg (1.89 mmol, 68%). 1H
NMR (500.1 MHz): δ 7.07−7.10 (m, 2 H; H-5, SC5H4N), 7.16−7.23
(m, 3 H; H-3/H-4/H-5, C6H5), 7.44−7.46 (m, 2 H; H-3, SC5H4N),
7.63−7.64 (m, 2 H; H-2/H-6, C6H5), 7.73−7.75 (m, 2 H; H-4,
SC5H4N), 8.31 (br s, 2 H; H-6, SC5H4N). 13C{1H} NMR (125.8
MHz): δ 118.4 (C-5, SC5H4N), 125.2 (C-3, SC5H4N), 127.3 (C-3/C-
5, C6H5), 127.9 (C-4, C6H5), 132.3 (C-2/C-6, C6H5), 140.9 (C-6,
SC5H4N), 141.6 (C-4, SC5H4N), 153.1 (C-1, C6H5), 167.1 (C-2,
SC5H4N). 29Si{1H} NMR (99.4 MHz): δ −164.4. 15N VACP/MAS
NMR: δ −133.5, −109.1. 29Si HPDec/MAS NMR: δ −167.8 to
−160.0. Anal. Calcd for C16H13BrN2S2Si (405.41): C, 47.40; H, 3.23;
N, 6.91; S, 15.82. Found: C, 47.7; H, 3.2; N, 7.1; S, 16.1.
Phenyl(thiocyanato-N)bis[N,S-pyridine-2-thiolato(−)]silicon-
(IV) (10). Potassium thiocyanate (482 mg, 4.96 mmol) was added at
20 °C in a single portion to a stirred solution of 5 (1.63 g, 4.52 mmol)
in acetonitrile (40 mL), and the reaction mixture was then stirred at
this temperature for 3 days. The solvent was removed in vacuo, and
dichloromethane (40 mL) was added to the residue. The resulting
precipitate was filtered off, washed with dichloromethane (2 × 10 mL),
and discarded, and the solvent of the filtrate (including the wash
solutions) was removed in vacuo, followed by the addition of
acetonitrile (45 mL). The resulting suspension was heated until a clear
solution was obtained, which was then cooled slowly to 20 °C and
kept undisturbed at this temperature for 2 days. The resulting colorless
crystalline solid was isolated by filtration, washed sequentially with
diethyl ether (2 × 10 mL) and n-pentane (2 × 5 mL), and dried in
1
vacuo (20 °C, 4 h, 0.01 mbar). Yield: 1.43 g (3.73 mmol, 83%). H
NMR (300.1 MHz): δ 7.08−7.13 (m, 2 H; H-5, SC5H4N), 7.22−7.29
(m, 3 H; H-3/H-4/H-5, C6H5), 7.44−7.48 (m, 2 H; H-3, SC5H4N),
7.60−7.66 (m, 2 H; H-2/H-6, C6H5), 7.72−7.78 (m, 2 H; H-4,
SC5H4N), 8.02 (br s, 2 H; H-6, SC5H4N). 13C{1H} NMR (75.5
MHz): δ 118.4 (C-5, SC5H4N), 125.6 (C-3, SC5H4N), 127.6 (C-3/C-
5, C6H5), 128.2 (C-4, C6H5), 133.0 (C-2/C-6, C6H5), 140.5 (C-6,
SC5H4N), 141.5 (C-4, SC5H4N), 150.3 (C-1, C6H5), 167.6 (C-2,
SC5H4N). 29Si{1H} NMR (99.4 MHz): δ −168.7. 15N VACP/MAS
NMR: δ −233.9 (NCS), −136.0 (SC5H4N), −110.7 (SC5H4N). 29Si
VACP/MAS NMR: δ −170.3. Anal. Calcd for C17H13N3S3Si (383.59):
C, 53.23; H, 3.42; N, 10.95; S, 25.08. Found: C, 53.2; H, 3.4; N, 10.9;
S, 24.9.
Chloromethylbis[N,S-pyridine-2-thiolato(−)]silicon(IV) (11).
Triethylamine (2.03 g, 20.1 mmol) and trichloromethylsilane (1.50
g, 10.0 mmol) were added at 20 °C in single portions one after
another to a stirred solution of 2-pyridinethiol (2.23 g, 20.1 mmol) in
tetrahydrofuran (40 mL), and the reaction mixture was then stirred at
this temperature for 24 h. The resulting precipitate was filtered off,
washed with tetrahydrofuran (2 × 10 mL), and discarded. The solvent
of the filtrate (including the wash solutions) was removed in vacuo,
Azidophenylbis[N,S-pyridine-2-thiolato(−)]silicon(IV) (8).
Azidotrimethylsilane (361 mg, 3.13 mmol) was added at 20 °C in a
single portion to a stirred solution of 5 (1.13 g, 3.13 mmol) in
acetonitrile (30 mL), and the reaction mixture was then stirred at this
temperature for 2 days. The solvent and the generated chlorotrime-
thylsilane were removed in vacuo, followed by the addition of
acetonitrile (20 mL). The resulting suspension was heated until a clear
solution was obtained, which was then cooled slowly to 20 °C and
kept undisturbed at this temperature for 2 days. The resulting colorless
crystalline solid was isolated by filtration, washed sequentially with
diethyl ether (2 × 10 mL) and n-pentane (2 × 5 mL), and dried in
1
vacuo (20 °C, 4 h, 0.01 mbar). Yield: 875 mg (2.38 mmol, 76%). H
NMR (300.1 MHz): δ 7.04−7.09 (m, 2 H; H-5, SC5H4N), 7.20−7.27
(m, 3 H; H-3/H-4/H-5, C6H5), 7.43−7.46 (m, 2 H; H-3, SC5H4N),
7.60−7.65 (m, 2 H; H-2/H-6, C6H5), 7.69−7.76 (m, 2 H; H-4,
SC5H4N), 7.93 (br s, 2 H; H-6, SC5H4N). 13C{1H} NMR (75.5
K
dx.doi.org/10.1021/ic401698a | Inorg. Chem. XXXX, XXX, XXX−XXX

Inorganic Chemistry
Article
followed by the addition of acetonitrile (21 mL). The resulting
suspension was heated until a clear solution was obtained, which was
then cooled slowly to 20 °C and kept undisturbed at this temperature
for 2 days. The resulting colorless crystalline solid was isolated by
filtration, washed sequentially with diethyl ether (2 × 10 mL) and n-
pentane (2 × 5 mL), and dried in vacuo (20 °C, 4 h, 0.01 mbar).
(+49)931-31-85250 (R.T.). Fax: (+31)20-59-87629 (F.M.B.),
(+49)931-31-84609 (R.T.).
Notes
The authors declare no competing financial interest.
1
Yield: 2.93 g (9.80 mmol, 98%). H NMR (300.1 MHz): δ 1.12 (s, 3
ACKNOWLEDGMENTS
■
H; CH3), 6.99−7.04 (m, 2 H; H-5, SC5H4N), 7.39−7.43 (m, 2 H; H-3,
SC5H4N), 7.67−7.73 (m, 2 H; H-4, SC5H4N), 7.99−8.01 (m, 2 H; H-
6, SC5H4N). 13C{1H} NMR (75.5 MHz): δ 26.0 (CH3), 117.9 (C-5,
SC5H4N), 125.4 (C-3, SC5H4N), 140.4 (C-6, SC5H4N), 141.0 (C-4,
SC5H4N), 168.1 (C-2, SC5H4N). 29Si{1H} NMR (59.6 MHz): δ
−148.3. 15N VACP/MAS NMR: δ −129.8, −104.5. 29Si VACP/MAS
NMR: δ −150.1 to −149.4. Anal. Calcd for C11H11ClN2S2Si (298.89):
C, 44.20; H, 3.71; N, 9.37; S, 21.46. Found: C, 44.1; H, 3.7; N, 9.3; S,
21.7.
We thank the National Research School Combination
Catalysis (NRSC-C) and The Netherlands Organization for
Scientific Research (NWO-CW and NWO-EW) for financial
support. We thank the SARA supercomputer center in
Amsterdam for excellent support.
REFERENCES
■
(1) (a) Junold, K.; Burschka, C.; Bertermann, R.; Tacke, R. Dalton
Trans. 2010, 39, 9401−9413. (b) Junold, K.; Baus, J. A.; Burschka, C.;
Tacke, R. Angew. Chem. 2012, 124, 7126−7129; Angew. Chem., Int. Ed.
2012, 51, 7020−7023.
Phenylbis[N,S-pyridine-2-thiolato(−)]silicon(IV) Iodide (12).
Iodotrimethylsilane (1.39 g, 6.95 mmol) was added at 20 °C in a single
portion to a stirred solution of 5 (1.00 g, 2.77 mmol) in acetonitrile
(30 mL), and the reaction mixture was then stirred at 65 °C for 3 h
and at 20 °C for 3 days. The solvent and the generated
chlorotrimethylsilane were removed in vacuo, followed by the addition
of acetonitrile (23 mL). The resulting suspension was heated until a
clear solution was obtained, which was then cooled slowly to 20 °C
and kept undisturbed at this temperature for 2 days. The resulting
colorless crystalline solid was isolated by filtration, washed with n-
pentane (2 × 5 mL), and dried in vacuo (20 °C, 4 h, 0.01 mbar).
(2) Selected publications dealing with higher-coordinate silicon(IV)
complexes with sulfur ligand atoms: (a) Tacke, R.; Mallak, M.;
Willeke, R. Angew. Chem. 2001, 113, 2401−2403; Angew. Chem., Int.
Ed. 2001, 40, 2339−2341. (b) Naganuma, K.; Kawashima, T. J.
Organomet. Chem. 2002, 643−644, 504−507. (c) Bertermann, R.;
Biller, A.; Kaupp, M.; Penka, M.; Seiler, O.; Tacke, R. Organometallics
2003, 22, 4104−4110. (d) Troegel, D.; Burschka, C.; Riedel, S.;
Kaupp, M.; Tacke, R. Angew. Chem. 2007, 119, 7131−7135; Angew.
Chem., Int. Ed. 2007, 46, 7001−7005. (e) Metz, S.; Burschka, C.;
Platte, D.; Tacke, R. Angew. Chem. 2007, 119, 7136−7139; Angew.
Chem., Int. Ed. 2007, 46, 7006−7009. (f) So, C.-W.; Roesky, H. W.;
Oswald, R. B.; Pal, A.; Jones, P. G. Dalton Trans. 2007, 5241−5244.
(g) Metz, S.; Burschka, C.; Tacke, R. Eur. J. Inorg. Chem. 2008, 4433−
4439. (h) Metz, S.; Burschka, C.; Tacke, R. Organometallics 2009, 28,
2311−2317. (i) Theis, B.; Metz, S.; Burschka, C.; Bertermann, R.;
Maisch, S.; Tacke, R. Chem.Eur. J. 2009, 15, 7329−7338. (j) See ref
1
Yield: 832 mg (1.84 mmol, 66%). H NMR (300.1 MHz): δ 7.33−
7.39 (m, 2 H; H-3/H-5, C6H5), 7.41−7.42 (m, 1 H; H-4, C6H5),
7.43−7.48 (m, 2 H; H-5, SC5H4N), 7.61−7.66 (m, 2 H; H-2/H-6,
C6H5), 7.72−7.75 (m, 2 H; H-3, SC5H4N), 8.10−8.15 (m, 2 H; H-4,
SC5H4N), 8.26−8.29 (m, 2 H; H-6, SC5H4N). 13C{1H} NMR (75.5
MHz): δ 122.0 (C-5, SC5H4N), 124.8 (C-3, SC5H4N), 128.9 (C-3/C-
5, C6H5), 131.4 (C-4, C6H5), 133.0 (C-2/C-6, C6H5), 142.9 (C-6,
SC5H4N), 144.7 (C-4, SC5H4N), 161.2 (C-2, SC5H4N), (C-1, C6H5)
not detected. 29Si{1H} NMR (99.4 MHz, −70 °C): δ −77.2. 15N
VACP/MAS NMR: δ −126.6. 29Si VACP/MAS NMR: δ −76.5. Anal.
Calcd for C16H13IN2S2Si (452.41): C, 42.48; H, 2.90; N, 6.19; S,
14.18. Found: C, 42.2; H, 3.0; N, 6.3; S, 14.3.
1a. (k) Wagler, J.; Brendler, E.; Langer, T.; Pottgen, R.; Heine, T.;
̈
Zhechkov, L. Chem.Eur. J. 2010, 16, 13429−13434. (l) Metz, S.;
Theis, B.; Burschka, C.; Tacke, R. Chem.Eur. J. 2010, 16, 6844−
6856. (m) Kobelt, C.; Burschka, C.; Bertermann, R.; Fonseca Guerra,
C.; Bickelhaupt, F. M.; Tacke, R. Dalton Trans. 2012, 41, 2148−2162.
(n) Junold, K.; Baus, J. A.; Burschka, C.; Auerhammer, D.; Tacke, R.
Chem.Eur. J. 2012, 18, 16288−16291.
Crystal Structure Analyses. Suitable single crystals of 4−6 and
8−12 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 diffractometer, graphite-monochromated
Mo Kα radiation, λ = 0.71073 Å). All structures were solved by direct
methods (SHELXS-97) and refined against all data by full-matrix least-
squares methods on F2 (SHELXL-97).23 SHELXLE24 was used as
refinement GUI. The non-hydrogen atoms were refined anisotropi-
cally.23 A riding model was employed in the refinement of the CH
hydrogen atoms. The crystallographic data for the structures reported
in this paper have been deposited with The Cambridge Crystallo-
graphic Data Centre as supplementary publications CCDC 948366−
948373.
(3) Selected publications dealing with higher-coordinate silicon(IV)
complexes with pyridine-type ligands: (a) Wannagat, U.; Hensen, K.;
Petesch, P.; Vielberg, F. Monatsh. Chem. 1967, 98, 1415−1422.
(b) Kummer, D.; Koster, H. Angew. Chem. 1969, 81, 897−898; Angew.
̈
Chem., Int. Ed. Engl. 1969, 8, 878−879. (c) Kummer, D.; Balkir, A.;
Koster, H. J. Organomet. Chem. 1979, 178, 29−54. (d) Kummer, D.;
̈
Chaudhry, S. C.; Debaerdemaeker, T.; Thewalt, U. Chem. Ber. 1990,
123, 945−951. (e) Kummer, D.; Chaudhry, S. C.; Depmeier, W.;
Mattern, G. Chem. Ber. 1990, 123, 2241−2245. (f) Fleischer, H.;
Hensen, K.; Stumpf, T. Chem. Ber. 1996, 129, 765−771. (g) Hensen,
K.; Stumpf, T.; Bolte, M.; Nather, C.; Fleischer, H. J. Am. Chem. Soc.
̈
ASSOCIATED CONTENT
■
1998, 120, 10402−10408. (h) Hensen, K.; Mayr-Stein, R.;
S
* Supporting Information
Spangenberg, B.; Bolte, M.; Ruhl, S. Z. Naturforsch. 2000, 55b, 248−
̈
252. (i) Hensen, K.; Kettner, M.; Stumpf, T.; Bolte, M. Z. Naturforsch.
2000, 55b, 901−906. (j) van den Ancker, T. R.; Raston, C. L.; Skelton,
B. W.; White, A. H. Organometallics 2000, 19, 4437−4444. (k) Jones,
C.; Junk, P. C.; Leary, S. G.; Smithies, N. A.; Steed, J. W. Inorg. Chem.
Commun. 2002, 5, 533−536. (l) Nakash, M.; Gut, D.; Goldvaser, M.
Inorg. Chem. 2005, 44, 1023−1030. (m) Wagler, J.; Schley, M.;
Crystallographic data for compounds 4−6 and 8−12 (Tables
S1 and S2), relative energies and bond lengths of selected
species in the gas phase (Figures S1 and S2), Cartesian
coordinates and total energies of selected species (Tables S3−
S10), and CIF files giving the crystallographic data for 4−6 and
8−12. This material is available free of charge via the Internet
at http://pubs.acs.org.
Gerlach, D.; Bohme, U.; Brendler, E.; Roewer, G. Z. Naturforsch. 2005,
̈
60b, 1054−1064. (n) Wagler, J.; Gerlach, D.; Roewer, G. Chem.
Heterocycl. Compd. 2006, 42, 1557−1567. (o) Brendler, E.; Wachtler,
̈
E.; Wagler, J. Organometallics 2009, 28, 5459−5465. (p) Fester, G. W.;
AUTHOR INFORMATION
■
Wagler, J.; Brendler, E.; Bohme, U.; Gerlach, D.; Kroke, E. J. Am.
̈
Corresponding Author
Chem. Soc. 2009, 131, 6855−6864. (q) Portius, P.; Davis, M. Dalton
Trans. 2010, 39, 527−532. (r) Portius, P.; Filippou, A. C.;
Schnakenburg, G.; Davis, M.; Wehrstedt, K.-D. Angew. Chem. 2010,
*E-mail: f.m.bickelhaupt@vu.nl (F.M.B.), r.tacke@uni-
wuerzburg.de (R.T.). Phone: (+31)20-59-87617 (F.M.B.),
L
dx.doi.org/10.1021/ic401698a | Inorg. Chem. XXXX, XXX, XXX−XXX

Inorganic Chemistry
Article
122, 8185−8189; Angew. Chem., Int. Ed. 2010, 49, 8013−8016.
(s) Fester, G. W.; Eckstein, J.; Gerlach, D.; Wagler, J.; Brendler, E.;
Kroke, E. Inorg. Chem. 2010, 49, 2667−2673. (t) Junold, K.; Burschka,
C.; Bertermann, R.; Tacke, R. Dalton Trans. 2011, 40, 9844−9857.
(u) See ref 2k.
Polymer Chemistry; Wiley: New York, 2000; pp 97−114. (f) Tacke, R.;
Seiler, O. In Silicon Chemistry: From the Atom to Extended Systems;
Jutzi, P., Schubert, U., Eds.; Wiley-VCH: Weinheim, Germany, 2003;
pp 324−337. (g) Kost, D.; Kalikhman, I. Adv. Organomet. Chem. 2004,
50, 1−106. (h) Voronkov, M. G.; Trofimova, O. M.; Bolgova, Y. I.;
Chernov, N. F. Russ. Chem. Rev. 2007, 76, 825−845. (i) Kost, D.;
Kalikhman, I. Acc. Chem. Res. 2009, 42, 303−314. (j) Couzijn, E. P. A.;
Slootweg, J. C.; Ehlers, A. W.; Lammertsma, K. Z. Anorg. Allg. Chem.
2009, 635, 1273−1278.
(4) Selected transition-metal complexes with the N,S-pyridine-2-
thiolato(−) ligand: (a) Fletcher, S. R.; Skapski, A. C. J. Chem. Soc.,
Dalton Trans. 1972, 635−639. (b) Evans, I. P.; Wilkinson, G. J. Chem.
Soc., Dalton Trans. 1974, 946−951. (c) Mura, P.; Olby, B. G.;
Robinson, S. D. J. Chem. Soc., Dalton Trans. 1985, 2101−2112.
(d) Zhang, N.; Wilson, S. R.; Shapley, P. A. Organometallics 1988, 7,
1126−1131. (e) Umakoshi, K.; Ichimura, A.; Kinoshita, I.; Ooi, S.
Inorg. Chem. 1990, 29, 4005−4010. (f) Reynolds, J. G.; Sendlinger, S.
C.; Murray, A. M.; Huffman, J. C.; Christou, G. Inorg. Chem. 1995, 34,
5745−5752. (g) Su, W.; Hong, M.; Weng, J.; Cao, R.; Lu, S. Angew.
Chem. 2000, 112, 3033−3036; Angew. Chem., Int. Ed. 2000, 39, 2911−
2914. (h) Liaw, W.-F.; Lee, J.-H.; Gau, H.-B.; Chen, C.-H.; Jung, S.-J.;
Hung, C.-H.; Chen, W.-Y.; Hu, C.-H.; Lee, G.-H. J. Am. Chem. Soc.
2002, 124, 1680−1688. (i) Halder, P.; Paine, T. K. Inorg. Chem. 2011,
50, 708−710.
(10) The Berry distortion was analyzed by using the PLATON
program system: Spek, A. L. Acta Crystallogr., Sect. D 2009, 65, 148−
155.
(11) Because of a poor signal-to-noise ratio (despite a long
measurement time), analysis of the solid-state 15N NMR spectrum
was very difficult.
(12) Bohm, J.; Fenzke, D.; Pfeifer, H. J. Magn. Reson. 1983, 55, 197−
̈
204.
(13) (a) te Velde, G.; Bickelhaupt, F. M.; Baerends, E. J.; Fonseca
Guerra, C.; van Gisbergen, S. J. A.; Snijders, J. G.; Ziegler, T. J.
Comput. Chem. 2001, 22, 931−967. (b) http://www.scm.com.
(14) (a) Vosko, S. H.; Wilk, L.; Nusair, M. Can. J. Phys. 1980, 58,
1200−1211. (b) Becke, A. D. Phys. Rev. A 1988, 38, 3098−3100.
(c) Perdew, J. P. Phys. Rev. B 1986, 33, 8822−8824; Erratum: Phys.
Rev. B 1986, 34, 7406.
(15) (a) van Lenthe, E.; Baerends, E. J.; Snijders, J. G. J. Chem. Phys.
1994, 101, 9783−9792. (b) van Lenthe, E.; van Leeuwen, R.;
Baerends, E. J.; Snijders, J. G. Int. J. Quantum Chem. 1996, 57, 281−
293.
(5) Group 1 and 2 element complexes with ligands of the N,S-
pyridine-2-thiolato(−) type: (a) Chadwick, S.; Ruhlandt-Senge, K.
Chem.Eur. J. 1998, 4, 1768−1780. (b) Chadwick, S.; Englich, U.;
Senge, M. O.; Noll, B. C.; Ruhlandt-Senge, K. Organometallics 1998,
17, 3077−3086. (c) Sousa Pedrares, A.; Teng, W.; Ruhlandt-Senge, K.
Chem.Eur. J. 2003, 9, 2019−2024.
(6) Group 13 element complexes with ligands of the N,S-pyridine-2-
thiolato(−) type: (a) Castano, M. V.; San
́
chez, A.; Casas, J. S.; Sordo,
, J. L.; Piniella, J. F.; Solans, X.; Germain, G.;
̃
(16) (a) Klamt, A.; Schuurmann, G. J. Chem. Soc., Perkin Trans. 2
̈
̈
J.; Brianso
́
1993, 799−805. (b) Klamt, A. J. Phys. Chem. 1995, 99, 2224−2235.
Debaerdemaeker, T.; Glaser, J. Organometallics 1988, 7, 1897−1904.
(b) Rose, D. J.; Chang, Y. D.; Chen, Q.; Kettler, P. B.; Zubieta, J. Inorg.
Chem. 1995, 34, 3973−3979. (c) Landry, C. C.; Hynes, A.; Barron, A.
R.; Haiduc, I.; Silvestru, C. Polyhedron 1996, 15, 391−402. (d) Abram,
(c) Pye, C. C.; Ziegler, T. Theor. Chem. Acc. 1999, 101, 396−408.
(d) Swart, M.; Rosler, E.; Bickelhaupt, F. M. Eur. J. Inorg. Chem. 2007,
̈
3646−3654.
(17) (a) Bickelhaupt, F. M.; Baerends, E. J. In Reviews in
Computational Chemistry; Lipkowitz, K. B., Boyd, D. B., Eds.; Wiley-
VCH: New York, 2000; Vol. 15, pp 1−86. (b) Bickelhaupt, F. M.;
Diefenbach, A.; de Visser, S. P.; de Koning, L. J.; Nibbering, N. M. M.
J. Phys. Chem. A 1998, 102, 9549−9553.
S.; Maichle-Mossmer, C.; Abram, U. Polyhedron 1997, 16, 2291−2298.
̈
(7) Group 14 element complexes with ligands of the N,S-pyridine-2-
thiolato(−) type: (a) Masaki, M.; Matsunami, S. Bull. Chem. Soc. Jpn.
1976, 49, 3274−3279. (b) Damude, L. C.; Dean, P. A. W.;
Manivannan, V.; Srivastava, R. S.; Vittal, J. J. Can. J. Chem. 1990, 68,
1323−1331. (c) Block, E.; Ofori-Okai, G.; Kang, H.; Wu, J.; Zubieta, J.
Inorg. Chim. Acta 1991, 190, 5−6. (d) Schmiedgen, R.; Huber, F.;
Preut, H.; Ruisi, G.; Barbieri, R. Appl. Organomet. Chem. 1994, 8, 397−
407. (e) Couce, M. D.; Faraglia, G.; Russo, U.; Sindellari, L.; Valle, G.
J. Organomet. Chem. 1996, 513, 77−83. (f) Couce, M. D.; Cherchi, V.;
Faraglia, G.; Russo, U.; Sindellari, L.; Valle, G.; Zancan, N. Appl.
Organomet. Chem. 1996, 10, 35−45. (g) Huber, F.; Schmiedgen, R.;
(18) (a) Bickelhaupt, F. M.; van Eikema Hommes, N. J. R.; Fonseca
Guerra, C.; Baerends, E. J. Organometallics 1996, 15, 2923−2931.
(b) Fonseca Guerra, C.; Handgraaf, J.-W.; Baerends, E. J.; Bickelhaupt,
F. M. J. Comput. Chem. 2004, 25, 189−210.
(19) (a) Swart, M.; Bickelhaupt, F. M. J. Chem. Theory Comput. 2006,
2, 281−287. (b) See ref 14. (c) van Zeist, W.-J.; Ren, Y.; Bickelhaupt,
F. M. Sci. China Chem. 2010, 53, 210−215.
(20) (a) Mulder, R. J.; Fonseca Guerra, C.; Bickelhaupt, F. M. J. Phys.
Chem. A 2010, 114, 7604−7608. (b) Ruiz, J. M.; Mulder, R. J.;
Fonseca Guerra, C.; Bickelhaupt, F. M. J. Comput. Chem. 2011, 32,
681−688.
Schurmann, M.; Barbieri, R.; Ruisi, G.; Silvestri, A. Appl. Organomet.
̈
Chem. 1997, 11, 869−888. (h) Sousa-Pedrares, A.; Casanova, M. I.;
́ ́
García-Vazquez, J. A.; Duran, M. L.; Romero, J.; Sousa, A.; Silver, J.;
Titler, P. J. Eur. J. Inorg. Chem. 2003, 678−686. (i) Ma, C.; Jiang, Q.;
Zhang, R. Can. J. Chem. 2004, 82, 608−615. (j) Xanthopoulou, M. N.;
Hadjikakou, S. K.; Hadjiliadis, N.; Kubicki, M.; Karkabounas, S.;
Charalabopoulos, K.; Kourkoumelis, N.; Bakas, T. J. Organomet. Chem.
2006, 691, 1780−1789.
(21) (a) Bento, A. P.; Bickelhaupt, F. M. J. Org. Chem. 2008, 73,
7290−7299. (b) Pierrefixe, S. C. A. H.; van Stralen, S. J. M.; van
Stralen, J. N. P.; Fonseca Guerra, C.; Bickelhaupt, F. M. Angew. Chem.
2009, 121, 6591−6593; Angew. Chem., Int. Ed. 2009, 48, 6469−6471.
(22) Berger, S.; Braun, S. 200 and More NMR Experiments: A
Practical Course; VCH: Weinheim, Germany, 2004; pp 141−144.
(23) Sheldrick, G. M. Acta Crystallogr., Sect. A 2008, 64, 112−122.
(8) Group 15 element complexes with ligands of the N,S-pyridine-2-
thiolato(−) type: (a) Preut, H.; Huber, F.; Hengstmann, K.-H. Acta
Crystallogr., Sect. C 1988, 44, 468−469. (b) Kennepohl, D. K.;
Pinkerton, A. A.; Lee, Y. F.; Cavell, R. G. Inorg. Chem. 1990, 29, 5088−
5096. (c) Hengstmann, K.-H.; Huber, F.; Preut, H. Acta Crystallogr.,
Sect. C 1991, 47, 2029−2032. (d) Block, E.; Ofori-Okai, G.; Kang, H.;
Wu, J.; Zubieta, J. Inorg. Chem. 1991, 30, 4784−4788.
(24) Hubschle, C. B.; Sheldrick, G. M.; Dittrich, B. J. Appl.
̈
Crystallogr. 2011, 44, 1281−1284.
(9) Selected reviews dealing with higher-coordinate silicon(IV)
compounds: (a) Holmes, R. R. Chem. Rev. 1996, 96, 927−950.
(b) Pestunovich, V.; Kirpichenko, S.; Voronkov, M. In The Chemistry
of Organic Silicon Compounds; Rappoport, Z., Apeloig, Y., Eds.; Wiley:
Chichester, U.K., 1998; Vol. 2, Part 2, pp 1447−1537. (c) Chuit, C.;
Corriu, R. J. P.; Reye, C. In Chemistry of Hypervalent Compounds;
Akiba, K.-y., Ed.; Wiley-VCH: New York, 1999; pp 81−146.
(d) Tacke, R.; Pulm, M.; Wagner, B. Adv. Organomet. Chem. 1999,
̈
44, 221−273. (e) Brook, M. A. Silicon in Organic, Organometallic and
M
dx.doi.org/10.1021/ic401698a | Inorg. Chem. XXXX, XXX, XXX−XXX