Synthesis and characterization of benzonitrile-substituted silyl ethers

Article abstract of DOI:10.1080/10426500903074874

The silyl ethers (siloxanes) Me_4-xSi(OC₆H ₅CN)x (x = 1-4) (1-4), O(Si(OC₆H₄CN) (Me) ₂)₂ (5), and Me₃Si-O-C₆F ₄CN (6) have been synthesized by the

Full text of DOI:10.1080/10426500903074874

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Synthesis and Characterization
of Benzonitrile-Substituted
Silyl Ethers
Christopher Hubrich a , Axel Schulz a b , Harald
Brand c & Alexander Villinger a
a Universität Rostock, Institut für Chemie, Abteilung
Anorganische Chemie, Rostock, Germany
b Leibniz-Institut für Katalyse e.V. an der Universität
Rostock, Rostock, Germany
c Department Chemie und Biochemie, Ludwig-
Maximilians-Universität München, München,
Germany
Published online: 04 Sep 2009.
To cite this article: Christopher Hubrich , Axel Schulz , Harald Brand & Alexander
Villinger (2009) Synthesis and Characterization of Benzonitrile-Substituted Silyl
Ethers, Phosphorus, Sulfur, and Silicon and the Related Elements, 184:9, 2179-2196
To link to this article: http://dx.doi.org/10.1080/10426500903074874
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Phosphorus, Sulfur, and Silicon, 184:2179–2196, 2009
Copyright © Taylor & Francis Group, LLC
ISSN: 1042-6507 print / 1563-5325 online
DOI: 10.1080/10426500903074874
Synthesis and Characterization of
Benzonitrile-Substituted Silyl Ethers
Christopher Hubrich,1 Axel Schulz,1,2 Harald Brand,3 and
Alexander Villinger1
1Universita¨t Rostock, Institut fu¨r Chemie, Abteilung Anorganische
Chemie, Rostock, Germany
2Leibniz-Institut fu¨r Katalyse e.V. an der Universita¨t Rostock, Rostock,
Germany
3Department Chemie und Biochemie, Ludwig-Maximilians-Universita¨t
Mu¨nchen, Mu¨nchen, Germany
The silyl ethers (siloxanes) Me4−xSi(OC6H5CN)x (x = 1–4) (1–4), O(Si(OC6H4CN)
(Me)2)2 (5), and Me3Si–O–C6F4CN (6) have been synthesized by the reaction of the
respective p-hydroxybenzonitriles and chlorosilanes in the presence of N,N,Nꢀ,Nꢀ-
tetramethylethylenediamine (TMEDA) as hydrogen chloride acceptor. All com-
pounds have been fully characterized by CHN-analysis, melting point, IR, Raman,
mass spectroscopy, and 1H, 13C, 29Si NMR spectroscopy. Furthermore, the crystal
structures of these compounds—with the exception of Me2Si(OC6H5CN)2, which is
a liquid—were determined by X-ray diffractometry.
Keywords Benzonitrile substituted silyl ethers; crystal structure; (p-cyanophenoxy)-
silanes; perfluorinated compounds; siloxanes; synthesis
INTRODUCTION
Silyl ethers (siloxanes) have many applications in polymer chem-
istry and also in organic chemistry as protecting groups. Aromatic
silyl ethers of the composition Me4−xSi(OC6H5)x (x = 1–4)1−4 and
O(Si(OC6H5)(Me)2)52 have been known for a long time. In contrast,
there are only two examples of the analogous compounds with a
Received 7 May 2009; accepted 28 May 2009.
We are indebted to Prof. T. M. Klapo¨tke (LMU Mu¨nchen) for the allocation of X-
ray measurement time and to Dr. Kurt Polborn (formerly LMU Mu¨nchen) for the X-ray
analysis of compound 1.
Address correspondence to Axel Schulz, Universita¨t Rostock, Institut fu¨r Chemie,
Abteilung Anorganische Chemie, Albert-Einstein-Straße 3a, 18059 Rostock, Germany.
E-mail: axel.schulz@uni-rostock.de
2179

2180
C. Hubrich et al.
benzonitrile instead of a phenyl group: (p-cyanophenoxy)trimethyl-
silane, Me3Si O−C6H4CN6 (1) and bis(p-cyanophen-oxy)dimethyl-
silane Me2Si(−O−C6H4CN)2 (2).7 Both compounds have been only par-
tially characterized.
Furthermore, the utilization of fluorinated silyl ethers like
Me3SiOC6F4X (X = H, F)8−11 as transfer agents has provided a power-
ful preparative pathway for the synthesis of new and difficultly accessi-
ble per- and polyfluorinated compounds.8,12 Me3SiOC6F5 has been also
used for the syntheses of metal complexes,13−15 alky- or aryloxysilyl-
substituted lactams,16 aryloxy-substituted sulfur(IV)fluorides,17 and
polyfluorinated phenyl-phosphonium ions.18 Other studies have in-
volved the reactivity19 and detailed analytical characterizations20 of
this compound. To the best of our knowledge, the analogous compound
of Me3SiOC6F5 with a fluorinated benzonitrile group, however, is not
known so far.
In this article, we report on the synthesis and full characterization
of the silyl ethers Me4−xSi(OC6H5CN)x (x = 1–4) (1–4). In addition, the
silyl ethers O(Si(OC6H4CN)(Me)2)2 (5) and Me3Si O−C6F4CN (6), the
perfluorinated analogous of 1, were prepared and fully characterized.
The crystal structures of the compounds 1 and 3–6 were determined by
X-ray studies and are discussed herein.
RESULTS AND DISCUSSION
Synthesis
The silyl ethers Me4−xSi(OC6H5CN)x (x = 1–4) (1–4) were syn-
thesized by the reaction of p-cyanophenol with the respec-
tive (methyl)chlorosilanes in tetrahydrofuran, whereas N,N,Nꢀ,Nꢀ-
tetramethylethylenediamine (TMEDA) was added as hydrogen chlo-
ride acceptor (Scheme 1).
The silyl ethers Me4−xSi(OC6H4CN)x (x = 1–3) (1)–(3) were obtained
after removal of the solvent under vacuum as (colorless) oils, while
Si(OC6H4CN)4 (4) was obtained as a brown solid. (Me3Si)OC6H4CN
(1) was purified by vacuum distillation, and the obtained oil slowly
crystallized to give a colorless crystalline solid. In the case of
Me2Si(OC6H4CN)2 (2), we were not able to obtain crystals suitable for
an X-ray study, either by cooling with liquid nitrogen or by recrystalliza-
tion or further distillation (boiling point7b: 197–201◦C/10−3 mbar). The
oil obtained from the synthesis of MeSi(OC6H4CN)3 (3) was cooled with
liquid nitrogen under vacuum, yielding a colorless crystalline solid. Re-
crystallization of the solid from toluene afforded crystals of 3 suitable

Benzonitrile-Substituted Silyl Ethers
2181
SCHEME 1 x
tetramethylethylenediamine.
=
1
(1),
2
(2),
3
(3),
4
(4). tmeda
=
N,N,Nꢀ,Nꢀ-
for X-ray analysis. X-ray quality crystals of Si(OC6H4CN)4 (4) were also
obtained by recrystallization from toluene.
The silylethers 1–4 can be isolated in good yields (96–66%). These
yields are comparable with those reported in literature, e.g., 60–
70% can be achieved for 1, while Renga and Wang reported 88%6b
for the reaction of the phenol with trimethylsilyl trichloroacetate
(Cl3C)CO2(SiMe3) in the presence of a catalytic amount of K2CO3/18-
crown-6 at 150◦C. The yield of 2 (96%) is somewhat higher than that
reported by Ismail, who used cyclic silazanes as silylating reagent
(88%).7b
In a next series of reactions, we tried to prepare the analogous
disiloxanes utilizing the same procedure as described above. For in-
stance, 1,3-bis(p-cyanophenoxy)-1,1,3,3-tetramethyl-disiloxane (5) was
synthesized from O(ClSi(Me2))2, HOC6H4CN, and TMEDA in a 1:2:1
ratio (Scheme 2). Pure O(Si(Me2)OC6H4CN)2 (5) was obtained after re-
moval of the solvent as a brown solid (isolated yield 23%). Crystals of
5 suitable for X-ray analysis were obtained by recrystallization from
diethylether and toluene.
Analogous to the formation of 1, perfluorinated phenols such
as HOC6F4CN can also be transformed into (p-cyano-(tetrafluoro)-
phenoxy)-trimethylsilane (Me3Si)OC6F4CN (6) when Me3SiCl and
TMEDA are added (Scheme 3). Similar to 1, (Me3Si)OC6F4CN was
obtained as colorless oil after removal of the solvent under vacuum
(isolated yield 44%). Further purification including distillation and

2182
C. Hubrich et al.
SCHEME 2 tmeda = N, N, Nꢀ, Nꢀ-tetramethylethylenediamine.
SCHEME 3 tmeda = N,N,Nꢀ,Nꢀ-tetramethylethylenediamine.
recrystallization steps finally yielded crystalline 6, suitable for an X-ray
analysis.
Characterization
All silyl ethers 1–6 were characterized by CHN analysis, melting point,
1
IR, Raman, mass spectroscopy, and H, 13C, 29Si NMR spectroscopy.
(With the exception of 2, the crystal structures of all compounds could
be determined by X-ray analysis).
1
As expected, the resonances in the 29Si{ H} NMR spectra of
Me3SiO(C6H4)CN (δ = 22.31), Me2Si(O(C6H4)CN)2 (δ = −2.39), and
MeSi(O(C6H4)CN)3 (δ = −52.56) are shifted to a higher field with
progressive substitution of methyl- by NC(C6H4)O-groups, due to an
increasing shielding of the 29Si nucleus. Thus, the 29Si nuclei in
O(SiMe2(O(C6H4)CN))2 (δ = −10.52) are stronger shielded than those
in Me2Si(O(C6H4)CN)2 (δ = −10.52 vs. −2.39). By comparing the 29Si

Benzonitrile-Substituted Silyl Ethers
2183
NMR signals of Me3SiO(C6H4)CN (δ = 22.31) and Me3SiO(C6F4)CN
(δ = 30.29), the electron-withdrawing effect of fluorine clearly exhibits
in the low-field shift of the perfluorinated compound.
Following the tendency in the 29Si NMR spectra, the 13C NMR sig-
nals of the methyl group are also increasingly shifted to a higher
field [Me3SiO(C6H4)CN δ = −0.18, Me2Si(O(C6H4)CN)2 δ = − 2.64, and
MeSi(O(C6H4)CN)3 δ = − 6.19].
In the mass spectra of Me2Si(O(C6H4)CN)2, MeSi(O(C6H4)CN)3,
Si(O(C6H4)CN)4, and O(SiMe2(O(C6H4)CN))2, a cleavage of both oxy-
gen bonds in the phenolate substituent is observed. Hence, fragments
of benzonitrile (C6H4CN) and the corresponding silane fragments are
found.
As expected, the stretching vibration of the nitrile moiety in the
IR and Raman spectra of the compounds with an tetrahydro(p-
cyanophenoxy)-substituent are found between 2222 and 2229 cm−1 as
a strong (IR) or most intensive vibration (Raman), respectively. The
stretching vibrations of the nitrile moiety in (Me3Si)OC6F4CN (Raman:
ν = 2248 cm−1; IR: ν = 2238 cm−1) are shifted to higher wave numbers
in comparison with those in (Me3Si)OC6H4CN (Raman: ν = 2225 cm−1
IR: ν = 2225 cm−1).
;
X-Ray Analyses
Selected bond lengths and angles are listed in Table I, crystallographic
data in Table II.
(Me3Si)OC6H4CN (1) crystallizes in the orthorhombic space group
Pnma with four molecules in the unit cell (Figure 1). Except for two of
the methyl groups attached to the silicon atom, all nonhydrogen atoms
lie in a mirror plane [ (C4−C3−O Si) = 180◦]. As was found for the
other silyl ethers 2–6, the silicon atom sits in a distorted tetrahedral
FIGURE 1 ORTEP drawing of (Me3Si)OC6H4CN (1). Thermal ellipsoids with
50% probability at 295 K (hydrogen atoms omitted). Symmetry operator: i = x,
−y + 0.5, z.

2184
C. Hubrich et al.
TABLE I Selected Bond Lengths (Å) and Angles (◦) in 1 and 3–6
Compound
Si O [Å]
O
C [Å]
Si
O
C [◦]
C
Si O [◦]
O
Si O [◦]
1
1.6663 (16)
1.3574 (17)
133.09 (12)
103.83 (10)
109.80 (5)
—
—
111.12 (7)
3
4
1.619 (2)a
1.621 (2)a
1.629 (3)a
1.617 (2)b
1.618 (2)b
1.630 (2)b
1.379 (3)a
1.374 (3)a
1.374 (3)a
1.376 (3)b
1.382 (3)b
1.368 (3)b
129.40 (19)a
125.37 (17)a
127.44 (17)a
129.47 (18)b
124.62 (17)b
129.73 (18)b
114.19 (13)a
112.83 (14)a
112.11 (12)a
114.53 (13)b
112.60 (14)b
112.19 (13)b
106.38 (11)a
105.11 (10)a
105.50 (11)a
106.36 (10)b
105.48 (11)b
104.92 (11)b
108.60 (10)
107.85 (10)
112.51 (10)
113.75 (10)
106.49 (9)
1.5997 (18)
1.6080 (18)
1.6175 (18)
1.6209 (17)
1.390 (3)
1.393 (3)
1.383 (3)
1.391 (3)
127.36 (16)
129.28 (15)
135.60 (16)
126.13 (15)
—
107.73 (9)
108.60 (8)
5
6
1.360 (3)
130.60 (19)
103.88 (12)e
109.79 (12)e
112.31 (14)f
108.12 (13)f
108.29 (16)
107.23 (18)
102.55 (19)
1.6278 (11)c
1.6582 (19)d
1.684 (3)
1.337 (4)
134.4 (2)
—
aMolecule 1 in the asymmetric unit (Figure 5).
bMolecule 2 in the asymmetric unit.
cSi
dSi
O
O
Si bond.
C bond (Figure 8).
eC Si O2 angle (Figure 8).
f C Si O1 angle.
environment [ (O Si C) or (C Si C) = 104–111◦]. The Si O bond
length of 1.666(2) Å is slightly shorter than expected for a typical Si O
bond [cf. d(Si O) 1.77 Å].21 The C N bond length of 1.131(3) Å is in the
expected range and in accordance with those found for compounds 3–6.
In the unit cell, an interesting π stacking between the aromatic rings
is observed (Figure 2). The molecules attached mutually by π stacking
to adopt a “head-to-tail” configuration.
In contrast to 1, the perfluorinated analogous (Me3Si)OC6F4CN (6)
crystallizes in the triclinic space group P − 1 with two molecules in the
unit cell (Figure 3). The Me3Si group is rotated out of the plane formed
by the O(C6F4)CN-unit [ (C2−C1−O Si) = 115.2 (4)◦]. Due to the
electron-withdrawing effect of fluorine, the C O bond length of 1.337
(4) Å is slightly shortened compared to that in (Me3Si)OC6H4CN (1)

Benzonitrile-Substituted Silyl Ethers
2185
TABLE II Crystallographic Details of 1 and 3–6
1
3
4
5
6
Chem. formula
Form. wt. [g
C10H13NOSi C22H15N3O3Si C28H16N4O4Si C18H20N2O3Si2 C10H9F4NOSi
191.30
397.46
500.54
368.54
263.27
mol−1
]
Color
Cryst. system
Space group
Colorless
Orthorhombic Orthorhombic
Colorless
Colorless
Triclinic
P-1
Colorless
Monoclinic
C2/c
Colorless
Triclinic
P-1
Pnma
P212121
12.995 (3)
16.392 (3)
a [Å]
b [Å]
8.7307 (17)
7.1399 (14)
10.6822 (15)
11.1981 (18)
15.392 (3)
7.2588 (12)
7.5381 (13)
6.7615 (13)
c [Å]
α [◦]
β [◦]
γ [◦]
17.624 (4)
90.00
90.00
18.924 (4)
90.00
90.00
12.396 (2)
108.270 (15)
109.848 (14)
104.123 (13)
19.695 (3)
90.00
108.152 (15)
90.00
11.856 (2)
84.672 (14)
70.569 (15)
87.518 (14)
90.00
90.00
3
V [Å ]
1098.6 (4)
4
1.157
0.177
2410
4031.1 (14)
8
1.310
0.145
17707
1218.2 (4)
2
1.365
0.140
7166
1947.7 (6)
4
1.257
0.200
5430
609.11 (18)
2
1.435
0.226
3582
Z
ρ calc. [g cm−3
]
µ [mm−1
]
Measured
reflections
Independent
reflections
Reflections with
I ≥ 2σ(I)
Rint.
1205
1052
6358
4707
5517
2944
2220
1186
2748
1207
0.0184
408
0.0426
0.0406
1648
0.0390
0.0476
516
0.0555
0.0694
776
0.0549
0.0693
268
0.0635
F (000)
R1 (R [F2
>
2σ(F2)])
wR2 (F2)
GooF
0.1174
1.107
75
0.0796
0.999
525
0.1349
0.924
334
0.1191
0.981
114
0.1570
0.920
154
Parameters
CCDC #
733380
733381
733382
733383
733384
[1.357 (2) Å]. In contrast, the Si O bond length of 1.684 (3) Å is slightly
expanded [1: 1.666 (2) Å]. The C CN [1: 1.444 (3) Å, 6: 1.436 (5) Å] and
CN bond lengths [1: 1.131 (3) Å, 6: 1.142 (5) Å], respectively, are almost
identical in both compounds. Moreover, only small differences in the
C O Si angles have been observed for both compounds [1: = 133.09
(12)◦, 6: = 134.4 (2)◦].
Similar to 1, π stacking between the aromatic rings is observed in
the unit cell of 6, and the molecules attached mutually adopt a “head-
to-tail” configuration (Figure 4).
MeSi(OC6H4CN)3 (3) crystallizes in the orthorhombic space group
P212121 with eight molecules in the unit cell (Figure 5). The asym-
metric unit consists of two molecules of MeSi(OC6H4CN)3. Both inde-
pendent molecules display only small differences in bond lengths and

2186
C. Hubrich et al.
FIGURE 2 Unit cell of (Me3Si)OC6H4CN (1). Projection along [010].
angles. The Si O−C angles at the Si1-atom are 125.37 (17), 129.40
(19), and 127.44 (17)◦ and at the Si2-atom 129.47 (18), 124.62 (17),
and 129.73 (18)◦. Thus, these angles are slightly smaller compared to
those in (Me3Si)OC6H4CN (1) or (Me3Si)OC6F4CN (6). This observa-
tion can be explained by an increased steric repulsion between the
FIGURE 3 ORTEP drawing of (Me3Si)OC6F4CN (6). Thermal ellipsoids with
50% probability at 200 K (hydrogen atoms omitted).

Benzonitrile-Substituted Silyl Ethers
2187
FIGURE 4 Unit cell of (Me3Si)OC6F4CN (6). Projection along [010].
FIGURE 5 ORTEP drawing of MeSi(OC6H4CN)3 (3). Thermal ellipsoids with
50% probability at 173 K (hydrogen atoms omitted).

2188
C. Hubrich et al.
FIGURE 6 Unit cell of MeSi(OC6H4CN)3 (3). Projection along [100].
three OC6H4CN-units at the silicon atom. The Si–O bond lengths of
1.62−1.63 Å are slightly shortened (0.03 Å) compared with those in
(Me3Si)OC6H4CN. Both molecules in the asymmetric unit adopt a “pro-
peller” configuration, but none of them has exact local C3 symmetry.
In the unit cell, the molecules are arranged in such a way that
“zigzagging” channels are formed (Figure 6).
Si(OC6H4CN)4 (4) crystallizes in the triclinic space group P − 1 with
two molecules in the unit cell (Figure 7). As discussed before, the sil-
icon atom sits in a distorted tetrahedral environment and possesses
approximate local C2 symmetry. The Si–O bond lengths of 1.60−1.62 Å
are slightly shortened compared with those in Me3SiOC6H4CN [1.666
(2) Å] and MeSi(OC6H4CN)3 (1.62–1.63 Å). The Si O−C bond angles
vary much more than those in MeSi(OC6H4CN)3 (125−129◦). Two of
the four (p-cyanophenoxy)-units in 4 are always arranged parallel to
each other, while both pairs are almost perpendicular to one another
(Figure 7).

Benzonitrile-Substituted Silyl Ethers
2189
FIGURE 7 ORTEP drawing of Si(OC6H4CN)4 (4). Thermal ellipsoids with
50% probability at 200 K (hydrogen atoms omitted).
O(Si(Me2)OC6H4CN)2 (5) crystallizes in the monoclinic space group
C2/c with four molecules in the unit cell (Figure 8). The molecule has
C2 symmetry, with a trans arrangement of both oxygen atoms along
the Si–Si axis [ O2−Si−Sii−O2i = 174.45 (17)◦]. The Si O bonds
of the Si O Si bridge [Si O1 = 1.6278 (11) Å] are slightly shorter
than the Si–O(p-cyanophenoxy) bonds [Si O2 = 1.6582 (19) Å]. In
FIGURE 8 ORTEP drawing of O(Si(Me2)OC6H4CN)2 (5). Thermal ellipsoids
with 50% probability at 200 K (hydrogen atoms omitted). Symmetry operator:
i = −x +1, y, −z + 1.5.

2190
C. Hubrich et al.
FIGURE 9 Unit cell of O(Si(Me2)OC6H4CN)2 (5). Projection along [010].
the unit cell, alternating layers of benzonitrile units and layers of
O−(Me2)Si O Si(Me2)−O units (Figure 9) are found.
EXPERIMENTAL
General Information
All manipulations were carried out under oxygen- and moisture-
free conditions under nitrogen using standard Schlenk or
drybox techniques. Tetrahydrofuran, diethylether, toluene, and
N,N,Nꢀ,Nꢀ-tetramethylethylenediamine (TMEDA; Aldrich) were dried
over sodium and freshly distilled prior to use. Tetrafluoro-4-
hydroxybenzonitrile (HOC6F4CN) was prepared according to a proce-
dure in the literature.22 Me3SiCl (Merck), Me2SiCl2 (Acros), MeSiCl3

Benzonitrile-Substituted Silyl Ethers
2191
(Acros), SiCl4 (Acros), and (Me2(Cl)Si)2O (Acros) were always freshly
distilled prior to use. p-Cyanophenol (Fluka) was used as received.
1
1
NMR: H, 13C{ H}, 29Si, and 19F-NMR spectra were obtained on a
Jeol EX400 Delta, a Jeol EX 400 Eclipse or a Bruker ARX 300 spec-
trometer and were referenced internally to the deuterated solvent (13C,
δreference = 54 ppm) or to protic impurities in the deuterated solvent (1H,
δreference = 5.31 ppm). IR: Perkin-Elmer One FT-IR spectrometer with
a DuraSamplIRII Diamond ATR Sensor by SensIR Technologies. Ra-
man: Perkin Elmer Spectrum 2000R NIR FT-Raman, equipped with a
Nd:YAG-Laser (1064 nm). MS: JEOL MStation JMS 700. CHN anal-
yses: Analysator Elementar Vario EL. Melting points: Uncorrected
¨
(Buchi B540 or EZ-Melt, Stanford Research Systems).
X-Ray Structure Determination
X-ray quality crystals of 1, 3, 4, 5, and 6 were selected in Kel-F-oil
(Riedel deHaen) at ambient temperatures. All samples were cooled to
173(2) K (3) or 200 (2) K (4, 5, 6) during measurement. Compound
1 was measured at ambient temperatures (295 (2) K). The data were
collected on a Nonius MACH3 diffractometer (1), on a Bruker-Nonius
Apex X8 CCD diffractometer (3), or on a Oxford Xcalibur3 CCD diffrac-
tometer (4, 5, 6), using graphite-monochromated Mo Kα radiation (λ =
0.71073). The structures were solved by direct methods (SHELXS-97)23
and refined by full-matrix least squares procedures (SHELXL-97).24
Semi-empirical absorption corrections were applied for 1 (MolEN)25
and 3 (SADABS).26 All nonhydrogen atoms were refined anisotropi-
cally, and hydrogen atoms were included in the refinement at calcu-
lated positions using a riding model. The methyl group at C2 in 1 was
found to be disordered and was split in two parts. The occupancy of
each part was refined freely [0.62(2)/0.38 (2)].
Full crystallographic data are deposited at the Cambridge Crystal-
lographic Data Centre (CCDC), U.K.
Me3SiOC6H4CN (1)
To a solution of p-cyanophenol (13.79 g, 115.77 mmol, 1 eq) in 250 mL
tetrahydrofuran, Me3SiCl (12.58 g, 14.80 mL, 115.80 mmol, 1 eq) was
added at ambient temperature with stirring. To this reaction mixture,
Me2N(CH2)2NMe2 (6.73 g, 8.74 mL, 57.91 mmol, 0.5 eq) was added over
a period of 5 min. Subsequently, the resulting suspension was heated
under reflux for 6 h. After cooling, the mixture was filtered through
a G4 frit, and the insoluble solid was washed with tetrahydrofuran

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(2 × 10 mL). The filtrate and the washing solutions were combined,
and the solvent was distilled off under vacuum. The resulting oily red
residue was distilled under vacuum (10−2 mbar, 81◦C) yielding an oil,
which crystallized upon standing to give a colorless solid of 1. Yield:
14.59 g (76.26 mmol, 65.87%), mp 41◦C. IR (cm−1): ν = 3048 (w), 2961
(w), 2902 (w), 2559 (w), 2225 (m), 1602 (s), 1506 (vs), 1415 (w), 1288
(m), 1271 (s), 1253 (vs), 1168 (m), 1105 (w), 901 (s), 835 (vs), 755 (m),
695 (w), 641 (w). Raman (100 mW, 25◦C, cm−1): ν = 3078 (21), 2967 (9),
2903 (19), 2225 (100), 1603 (46), 1417 (3), 1293 (11), 1191 (9), 1173 (24),
906 (6), 850 (3), 775 (11), 645 (20), 591 (9), 548 (6), 481 (8), 342 (8), 248
(8), 199 (9), 160 (8). 1H NMR (CDCl3, 400 MHz, 25◦C): δ = 0.23 (s, 9H,
(H3C)3Si), 6.88 (d, J = 9.9 Hz, 2H, O-C-CH), 7.53 (d, J = 8.2 Hz, 2H,
NC C CH). 13C NMR (CDCl3, 101 MHz, 25◦C): δ = −0.18 ((H3C)3Si),
104.58 (C CN), 119.36 (CN), 121.00 (OC-CH), 133.81 (NC C CH),
1
159.43 (C O). 29Si{ H} NMR (CDCl3, 79 MHz, 25◦C): δ = 22.31 (s,
SiMe3). MS (EI+, 70 eV); m/z (%): 191 (27) [M]+, 177 (15), 176 (100) [M
− Me]+, 102 (6), 75 (16), 73 (12) [Me3Si]+, 43 (8), 28 (12), 18 (50), 17
(11). C10H13NOSi (191.30): calc: N 7.32%, C 62.79%, H 6.85%; found: N
7.31%, C 62.39%, H 7.33%.
Me2Si(OC6H4CN)2 (2)
2 was synthesized using the same method as for 1, but with the fol-
lowing quantities: p-cyanophenol (5.00 g, 41.97 mmol, 2 eq), 125 mL
tetrahydrofuran, Me2SiCl2 (2.70 g, 2.55 mL, 20.92 mmol, 1 eq), and
Me2N(CH2)2NMe2 (2.43 g, 3.16 mL, 20.91 mmol, 1 eq). 2 was afforded
as a colorless oil. Yield: 5.90 g (20.04 mmol, 95.66%). IR (cm−1): ν =
2967 (w), 2562 (w), 2226 (s), 1600 (s), 1498 (vs), 1415 (w), 1277 (m),
1249 (vs), 1168 (s), 1106 (w), 1015 (w), 911 (vs), 832 (s), 807 (s), 683 (w),
655 (w), 620 (w). Raman (100 mW, 25◦C, cm−1): ν = 3075 (21), 2968 (5),
2902 (11), 2228 (100), 1605 (77), 1285 (11), 1261 (9), 1190 (27), 1169
(37), 919 (5), 841 (17), 776 (25), 719 (5), 684 (10), 654 (10), 588 (4),
1
547 (6), 481 (7), 416 (6), 279 (7), 261 (7), 192 (11), 163 (11). H NMR
(C6D6, 400 MHz, 25◦C): δ = 0.13 (s, 6H, (H3C)2Si), 6.61 (d, J = 8.8 Hz,
2H, O-C-CH), 7.08 (d, J = 8.76 Hz, 2H, NC C CH). 13C NMR (C6D6,
101 MHz, 25◦C): δ = −2.66 ((H3C)2Si), 106.52 (C CN), 118.76 (CN),
1
120.59 (OC-CH), 134.28 (NC C CH), 157.37 (C O). 29Si{ H} NMR
(C6D6, 79 MHz, 25◦C): δ = −2.39 (Si(CH3)2). MS (DEI+, 70 eV); m/z
(%): 369 (11), 368 (37) [O(Me2SiOC6H4CN)2]+, 354 (6), 353 (19), 325
(8), 324 (29), 308 (5), 295 (9), 294 (39) [M]+, 279 (22) [M − Me]+, 261
(12), 252 (9), 251 (23), 250 (100), 236 (7), 235 (11), 234 (52), 177 (8),
176 (43) [Me2Si(OC6H4CN)]+, 160 (6), 133 (11), 119 (6), 116 (15), 102

Benzonitrile-Substituted Silyl Ethers
2193
(13) [C6H4CN]+, 90 (6), 75 (11), 73 (13). C16H14N2O2Si (294.38): Calc:
N 9.52%, C 65.28%, H 4.79%; found: N 9.63%, C 65.55%, H 4.89%.
MeSi(OC6H4CN)3 (3)
3 was synthesized using the same method as for 1, but with the fol-
lowing quantities: p-cyanophenol (7.50 g, 62.96 mmol, 3 eq), 250 mL
tetrahydrofuran, MeSiCl3 (3.14 g, 2.47 mL, 20.99 mmol, 1 eq), and
Me2N(CH2)2NMe2 (3.66 g, 4.75 mL 31.50 mmol, 1.5 eq). Cooling down
the afforded colorless oil with liquid nitrogen under vacuum twice gave
3 as a colorless, crystalline solid. Yield: 6.44 g (16.20 mmol, 77.18%).
Crystals suitable for X-ray analysis were grown in the following man-
ner: A small amount of 3 was dissolved in a little toluene, and the
solution was filtered through a G4 frit. The solvent was distilled off,
and the residual oil crystallized at ambient temperature for 2 days to
give colorless crystals. mp 82−83◦C. IR (cm−1): ν = 3100 (w), 3065 (w),
3002 (w), 2912 (w), 2567 (w), 2224 (vs), 1913 (w), 1600 (vs), 1497 (vs),
1416 (w), 1291 (w), 1283 (w), 1246 (vs), 1168 (s), 1108 (m), 1016 (w), 927
(vs), 841 (s), 826 (s), 801 (s), 771 (m), 739 (m), 662 (w), 638 (w), 601 (w).
Raman (100 mW, 25◦C, cm−1): ν = 3077 (26), 2984 (4), 2913 (9), 2229
(100), 1603 (48), 1299 (9), 1271 (6), 1191 (20), 1172 (21), 931 (8), 840
(6), 801 (18), 742 (11), 718 (6), 653 (7), 547 (6), 480 (7), 158 (9).1H NMR
(CDCl3, 300 MHz, 25◦C): δ = 0.62 (s, 3H, (H3C)Si), 7.04 (d, J = 8.9 Hz,
2H, O-C-CH), 7.59 (d, J = 8.8 Hz, 2H, NC C CH). 13C NMR (CDCl3, 76
MHz, 25◦C): δ = − 6.19 ((H3C)Si), 107.07 (C CN), 118.30 (CN), 120.36
1
(OC-CH), 134.36 (NC C CH), 155.72 (C O). 29Si{ H} NMR (CDCl3,
60 MHz, 25◦C): δ = −52.56 ((H3C)3Si). MS (DEI+, 70 eV); m/z (%): 399
(8), 398 (30), 397 (100) [M]+, 280 (6), 279 (27) [MeSi(OC6H4CN)2]+, 263
(6), 262 (8), 261 (36), 160 (7), 119 (9), 102 (7) [C6H4CN]+ . C22H15N3O3Si
(397.46): calc.: N 10.57%, C 66.48%, H 3.80%; found: N 10.22%, C
66.52%, H 4.40%.
Si(OC6H4CN)4 (4)
4 was synthesized using the same method as for 1, but with the fol-
lowing quantities: p-cyanophenol (30.00 g, 251.85 mmol, 4 eq), 250
mL tetrahydrofuran, SiCl4 (10.70 g, 7.23 mL, 62.98 mmol, 1 eq), and
Me2N(CH2)2NMe2 (14.63 g, 19.00 mL, 125.89 mmol, 2 eq). In this reac-
tion, the insoluable solid was washed with 100 mL of tetrahydrofuran.
The procedure afforded a brownish amorphous solid. Recrystallization
from toluene gave a reddish brown oil, from which crystals of 4 grew
at 0◦C. Yield: 26.26 g (52.46 mmol, 83.40%). Crystals suitable for X-ray

2194
C. Hubrich et al.
analysis were obtained by twice recrystallizing from diethylether fol-
lowed by twice recrystallizing from toluene. mp 131◦C. IR (cm−1): ν =
3273 (m), 3099 (m), 2569 (w), 2229 (s), 1908 (w), 1783 (w), 1599 (vs),
1494 (vs), 1450 (w), 1410 (w), 1374 (w), 1284 (m), 1230 (vs), 1163 (s),
1101 (m), 1015 (w), 998 (m), 961 (vs), 920 (m), 840 (s), 820 (m), 799
(m), 717 (w), 702 (w), 666 (m), 648 (w). Raman (200 mW, 25◦C, cm−1):
ν = 3076 (24), 2229 (100), 1600 (57), 1324 (6), 1299 (9), 1242 (9), 1190
(17), 1182 (13), 1167 (13), 918 (13), 772 (22), 649 (9), 243 (8), 192 (10),
145 (9). 1H NMR (CDCl3, 300 MHz, 25◦C): δ = 7.09 (d, J = 8.8 Hz, 2H,
O-C-CH), 7.63 (d, J = 8.9 Hz, 2H, NC C CH). 13C NMR (CDCl3, 76
MHz, 25◦C): δ = 108.07 (C CN), 117.97 (CN), 120.17 (OC-CH), 134.49
(NC C CH), 154.71 (C O). MS (DEI+, 70 eV); m/z (%): 502 (11), 501
(37), 500 (100) [M]+, 364 (10), 264 (6), 263 (29) [Si(OC6H4CN)2− H]+,
119 (25) [HOC6H4CN]+, 102 (12) [C6H4CN]+, 92 (10), 91 (16), 90 (5), 64
(6), 63 (6). C28H16N4O4Si (500.54): calc.: N 11.19%, C 67.19%, H 3.22%;
found: N 11.34%, C 65.93%, H 3.64%.
(Me2Si(OC6H4CN))2O (5)
5 was synthesized using the same method as for 1, but with the fol-
lowing quantities: p-cyanophenol (11.92 g, 100.07 mmol, 2 eq), 250 mL
tetrahydrofuran, (Me2(Cl)Si)2O (9.80 g, 9.52 mL, 48.23 mmol, 1 eq), and
Me2N(CH2)2NMe2 (5.81 g, 7.55 mL, 50.00 mmol, 1 eq). The procedure
gave a brown solid. Recrystallization from toluene followed by recrys-
tallization from diethylether three times afforded crystals of 5 suitable
for X-ray analysis. Yield: 5.54 g (11.07 mmol, 22.95%), mp 62–64◦C.
IR (cm−1): ν = 3076 (w), 3048 (w), 2968 (w), 2912 (w), 2561 (w), 2350
(w), 2286 (w), 2224 (s), 2172 (w), 1902 (w), 1603 (vs), 1560 (w), 1508
(vs), 1418 (w), 1285 (s), 1273 (vs), 1258 (vs), 1191 (w), 1173 (m), 1106
(w), 1052 (m, br), 960 (w), 944 (w), 913 (s), 836 (vs), 806 (vs), 800 (vs),
704 (w), 676 (m), 656 (m), 625 (w), 606 (m). Raman (100 mW, 25◦C,
cm−1): ν = 3076 (40), 2980 (20), 2910 (27), 2222 (100), 1606 (87), 1394
(7), 1286 (13), 1261 (9), 1191 (23), 1178 (35), 830 (10), 776 (23), 703
(9), 658 (10), 481 (13), 424 (9), 363 (17), 313 (10), 278 (11), 240 (13),
1
202 (19), 151 (8). H NMR (C6D6, 400 MHz, 25◦C): δ = 0.17 (s, 12H,
(H3C)2Si), 6.68 (d, 4H, J = 8.8 Hz), 7.14 (d, 4H, J = 7.7 Hz). 13C NMR
(C6D6, 101 MHz, 25◦C): δ = −0.87 ((H3C)2Si), 106.23 (C CN), 118.70
1
(CN), 120.00 (OC CH), 133.76 (NC C CH), 157.93 (C O). 29Si{ H}
NMR (C6D6, 79 MHz, 25◦C): δ = −10.52 ((H3C)2Si). MS (DEI+, 70 eV);
m/z (%): 398 (9), 370 (5), 369 (14), 368 (45) [M]+, 354 (7), 353 (24) [M
− Me]+, 252 (10), 251 (22), 250 (100) [(Me2Si)2O(OC6H4CN)]+, 236 (6),
235 (10) [(MeSiOSiMe2(OC6H4CN)]+, 234 (46), 176 (8), 133 (10), 119

Benzonitrile-Substituted Silyl Ethers
2195
(13), 116 (10), 102 (8) [C6H4CN]+, 91 (5), 75 (11), 73 (17). C18H20N2O3Si2
(368.53): calc.: N 7.60%, C 58.66%, H 5.47%; found: N 7.17%, C 56.93%,
H 5.36%.
Me3SiOC6F4CN (6)
6 was synthesized using the same method as for 1, but with the follow-
ing quantities: (tetrafluoro)-p-cyanophenol (5.27 g, 27.58 mmol, 1 eq),
125 mL tetrahydrofuran, Me3SiCl (3.02 g, 3.55 mL, 27.80 mmol, 1 eq),
and Me2N(CH2)2NMe2 (1.60 g, 2.08 mL, 13.77 mmol, 0.5 eq). The proce-
dure gave a yellow oily residue, which was distilled under vacuum (10−2
mbar, 60◦C) yielding an oil, from which crystals of 6 suitable for X-ray
analysis precipitated. Further stirring under vacuum afforded 6 as a
pale brown solid. Yield: 3.19 g (12.12 mmol, 43.93%), mp 102−104◦C.
IR (cm−1): ν = 3515 (w), 3427 (m), 3299 (w), 2961 (w), 2904 (w), 2350
(w), 2238 (w), 2050 (w), 1650 (vs), 1616 (m), 1517 (s), 1490 (vs), 1418
(s), 1396 (s), 1317 (m), 1290 (w), 1256 (vs), 1145 (s), 983 (vs), 925 (m),
841 (vs), 819 (s), 786 (m), 764 (m), 750 (s), 707 (w), 681 (w), 663 (m),
628 (m). Raman (100 mW, 25◦C, cm−1): ν = 2967 (23), 2908 (50), 2246
(88), 1651 (100), 1511 (9), 1443 (53), 1323 (11), 1168 (5), 630 (39), 524
(58), 478 (19), 431 (15), 407 (8), 390 (17), 340 (15), 314 (8), 238 (15),
1
185 (19), 132 (7). H NMR (CDCl3, 300 MHz, 25◦C): δ = −0.32 (s, 9H,
Si(CH3)3). 13C NMR (CDCl3, 25◦C, 75.47): δ = −0.05 ((CH3)3Si), 106.75
(t, C CN, 2JCF = 16.3 Hz), 136.85 (m, CN), 140.73 (dm, OC CF), 144.92
(dm, NC-C-CF), 160.79 (s, C O).19F NMR (CDCl3, 282.40 MHz, 25◦C):
1
δ = − 142.43 (dm, 2F), − 156.87 (dm, 2F). 29Si{ H} NMR (CDCl3, 59.67
MHz, 25◦C): δ = 30.29 (Si(CH3)3). MS (DEI+, 70 eV); m/z (%): 264 (9),
263 (55) [M]+, 249 (12), 248 (79) [M − Me]+, 191 (11), 170 (14), 148 (6),
147 (25), 124 (13), 120 (11), 81 (17), 78 (8), 77 (100) [Me2SiF]+, 76 (6),
75 (42), 74 (8), 73 (92) [Me3Si]+, 63 (9), 49 (11), 47 (17), 45 (8), 43 (8), 18
(29). C10H9F4NOSi (263.26): calc.: N 5.32%, C 45.62%, H 3.45%; found:
N 5.34%, C 45.48%, H 3.48%.
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