Synthesis of Functional Bis(pentafluoroethyl)silanes (C2F5)2SiX2, with X=H, F, Cl, Br, OPh, and O2CCF3

Article abstract of DOI:10.1002/chem.201603442

As recently shown, the introduction of pentafluoroethyl functionalities into silicon compounds is of general interest due to an enhanced Lewis acidity of the resulting species. By this means, the synthesis of previously inaccessible hypervalent silicon de

Full text of DOI:10.1002/chem.201603442

DOI: 10.1002/chem.201603442
Full Paper
&
Silicon Chemistry
Synthesis of Functional Bis(pentafluoroethyl)silanes (C F ) SiX ,
2
5 2
2
with X=H, F, Cl, Br, OPh, and O CCF3
2
[a]
[a]
[a]
[a]
Nico Schwarze, Boris Kurscheid, Simon Steinhauer, Beate Neumann, Hans-
[a]
[b]
[a]
Georg Stammler, Nikolai Ignat’ev, and Berthold Hoge*
Abstract: As recently shown, the introduction of pentafluor-
oethyl functionalities into silicon compounds is of general in-
terest due to an enhanced Lewis acidity of the resulting spe-
cies. By this means, the synthesis of previously inaccessible
sistant to oxonium cations, which is a key feature for the
[3]
preparation of stable pentafluoroethylsilic acids. Treatment
of dichlorodiphenoxysilane with in situ generated penta-
fluoroethyl lithium leads to the corresponding bis(penta-
fluoroethyl)silane in high yields. (C F ) Si(OPh) serves as
[
1]
hypervalent silicon derivatives is enabled. While an easy
access to tris(pentafluoroethyl)silanes has already been pub-
lished, synthetic strategies for the selective preparation of
bis derivatives are yet unknown. In this contribution, a con-
venient protocol for the synthesis of functional bis(penta-
fluoroethyl)silicon compounds is presented. These com-
pounds represent precursors for the synthesis of pentafluor-
2
5 2
2
a starting material for further functionalized bis(pentafluor-
oethyl)silanes. These silanes have been isolated and their re-
activity towards N bases studied. The pronounced Lewis
acidity of the obtained compounds has been documented
by the formation of octahedral adducts with nitrogen
donors such as 1,10-phenanthroline and acetonitrile.
[
2]
oethylated polysiloxanes. Furthermore, they prove to be re-
Introduction
In general, pentafluoroethyl element compounds exhibit
[4]
higher thermal stabilities than the trifluoromethyl analogues.
While (C F ) SiNEt shows no decomposition after 2 h at 1808C,
Scheme 1. Synthesis of difluoro- and trifluorotris(pentafluoroethyl)silicate by
pentafluoroethylation of SiCl .
4
2
5 3
2
(
CF ) SiNEt tends to violent decomposition even at room tem-
3 3 2
[
5]
perature. A similar trend can be observed for the correspond-
ing lithium perfluoroalkyl compounds. While LiCF is still elu-
3
sive, the persistence of LiC F at lower temperatures renders it
Silicate formation proceeds much faster than the C F group
2 5
2
5
[
6]
very useful for synthetic applications. At temperatures above
transfer. Thus the reaction of SiCl with less than four equiva-
4
À408C, the compound decomposes under formation of C F
lents of LiC F results in the exclusive formation of silicates,
2
4
2 5
and LiF. The thermal stability of LiC F strongly depends on the
rather than in the formation of neutral tris- or bis(pentafluoroe-
2
5
[8]
reaction conditions. In the presence of strong Lewis acids it de-
composes even at temperatures below À708C. Therefore, in
the presence of strong Lewis acids, LiC F behaves as a fluo-
thyl)silanes. In order to synthesize neutral tris(pentafluoroe-
thyl)silanes the silicate formation has to be avoided. Attaching
electron-donating groups to the silicon moiety leads to a signif-
icantly reduced Lewis acidity and allows, therefore, the selec-
tive synthesis of tris(pentafluoroethyl)silanes, such as
2
5
ride-ion donor rather than as a C F group transfer reagent.
2
5
Both pathways are followed in the reaction of SiCl4 with
an excess of LiC F , giving rise to the formation of fluoro-
[8]
(C F ) SiNEt and (C F ) SiCH .
2
5
2
5 3
2
2
5 3
3
2À
À
(
(
pentafluoroethyl)silicates [Si(C F ) F ]
and [Si(C F ) F ]
Surprisingly, the NEt group fails in the selective synthesis of
2
5 3
3
2
5 3
2
2
[
7]
Scheme 1).
bis(pentafluoroethyl)silanes (Scheme 2). It can be assumed that
due to steric issues, the reaction of Cl Si(NEt ) with LiC F gave
2
2 2
2 5
a complex mixture with (C F ) SiF(NEt ) as the major compo-
2
5 2
2
[
a] N. Schwarze, Dr. B. Kurscheid, Dr. S. Steinhauer, B. Neumann,
Dr. H.-G. Stammler, Prof. Dr. B. Hoge
Centrum fꢀr Molekulare Materialien
nent. It is obvious that the selective synthesis of bis(pentafluor-
oethyl)silane derivatives requires less bulky electron-donating
Fakultꢁt fꢀr Chemie, Anorganische Chemie II
Universitꢁt Bielefeld
Universitꢁtsstrasse 25, 33615 Bielefeld (Germany)
E-mail: b.hoge@uni-bielefeld.de
[b] Dr. N. Ignat’ev
Consultant, Merck KGaA
Frankfurter Straße 250, 64293 Darmstadt (Germany)
Scheme 2. Two-step synthesis of diethylaminotris(pentafluoroethyl)silane.
Chem. Eur. J. 2016, 22, 1 – 9
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substituents. The pentafluoroethylation of Ph SiCl or (p-tol-
2
2
yl) SiCl furnished (C F ) SiPh and (C F ) Si(p-tolyl) , respective-
2
2
2
5 2
2
2
5 2
2
ly. Because the attempted replacement of the aryl groups by
halides according to Scheme 3 failed to give functionalized
bis(perfluoroethyl)silanes (C F ) SiX we envisaged the phenoxy
Scheme 5. Synthesis of bis(pentafluoroethyl)dichlorosilane (3).
2
5 2
2
functionality as a leaving group.
The good accessibility of dichlorosilane 3 in a multigram
quantity is a prerequisite for the study of further chemical
transformations. Difluorobis(pentafluoroethyl)silane (4) was ob-
tained by stirring a slurry of antimony trifluoride in neat di-
[10c]
chlorosilane 3 at room temperature (Scheme 6).
After frac-
Scheme 3. Attempts to prepare functional bis(pentafluoroethyl)silanes by in-
troduction of aryl groups.
tional condensation, difluorosilane 4 was isolated as a colorless
liquid with a vapor pressure of 315 mbar at room temperature
in 96% yield. The melting point of difluorosilane 4 was esti-
29
In this article we report on the successful employment of
phenoxy groups for the high-yield synthesis of (C F ) Si(OPh)
mated to be about À1358C. The Si NMR spectrum of 4 re-
veals a triplet of quintets at d=À59.3 ppm with characteristic
2
5 2
2
1
2
in
multigram
quantities.
Further
derivatization
of
coupling constants of J(Si,F)=353 and J(Si,F)=45.6 Hz
(
C F ) Si(OPh) constitutes a route to a whole library of bis(pen-
(Table 2).
2
5 2
2
tafluoroethyl)silanes, (C F ) SiX , with X=H, F, Cl, Br, and
2
5 2
2
CF CO . The pronounced Lewis acidity of the obtained com-
3
2
pounds is documented by the formation of octahedral adducts
with nitrogen donors, such as 1,10-phenanthroline and aceto-
nitrile, [Si(C F ) X (phen)] and [Si(C F ) X (NCCH ) ], respectively.
2
5 2
2
2
5 2
2
3 2
Results and Discussion
Synthesis of bis(pentafluoroethyl)silanes
Dichlorodiphenoxysilane (1) was envisaged as an appropriate
starting material for the selective synthesis of bis(pentafluoroe-
thyl)silane derivatives. Stirring phenol with silicon tetrachloride
in diethyl ether at room temperature for two days afforded
Scheme 6. Synthesis of difluorosilane 4 (top) and silane 5 (bottom).
Reaction of 3 with a slight excess of tributyltin hydride selec-
[
9]
compound 1 in a 73% yield on a 100 g scale. Subsequent
treatment of 1 with in situ generated pentafluoroethyllithium
in diethylether at À858C yields bis(pentafluoroethyl)diphenox-
ysilane (2) as a colorless liquid in 74% yield (Scheme 4). Diphe-
noxysilane 2 represents a colorless liquid that can be handled
with common Schlenk techniques.
tively affords (C F ) SiH (5), which was separated from the re-
2 5 2 2
action mixture by a fractional condensation in 99% yield. The
product has a vapor pressure of 380 mbar at room tempera-
29
ture and melts at À958C. In the Si NMR spectrum the product
shows a triplet of quintets of septets splitting at d=
1
2
3
À40.6 ppm with characteristic J(Si,H), J(Si,F), and J(Si,F) cou-
plings of 243, 35.3, and 1.2 Hz, respectively (Figure 1 and
Scheme 4. Synthesis of dichlorodiphenoxysilane (1) and the subsequent re-
action with pentafluoroethyllithium yielding bis(pentafluoroethyl)diphenoxy-
silane (2).
Combining 2 with an excess of phenylacetyl chloride for six
days at 658C leads to the corresponding dichlorosilane 3 in
[
10a]
8
8% yield (Scheme 5).
trichloride accelerates the reaction significantly.
was obtained as a colorless liquid with a vapor pressure of
6 mbar at room temperature in 96% yield after stirring the re-
Addition of catalytic amounts of iron
[
10b]
Product 3
8
29
action mixture for only 2 h at room temperature. The Si NMR
2
9
19
29
19
Figure 1. Si F DEPT (top) and Si{ F} DEPT (bottom) NMR spectrum of
spectrum of silane 3 exhibits a quintet at d=À13.8 ppm with
29 19
bis(pentafluoroethyl)silane (5); right: detailed cut of the Si F-DEPT NMR
2
a J(Si,F) coupling constant of 47.1 Hz.
spectrum.
&
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19
29
Table 2). The F-decoupled Si NMR spectrum exhibits a triplet
due to the SiH coupling (J=243 Hz) (Figure 1, bottom).
The molecular structures of silanes 4 and 5 were elucidated
by in situ crystallization. This was achieved by first establishing
a solid–liquid equilibrium just below the melting point inside
a sealed capillary, then melting all the solid but for a tiny crys-
tal seed (using a thin copper wire as an external heat source)
followed by a slow chilling to the temperature of measure-
ment at 100 K.
Scheme 7. Synthesis of dibromosilane 6.
a colorless liquid with a vapor
pressure of 23 mbar at room tem-
perature and a melting point of
The SiÀF bond lengths of 4 in the crystal (Figure 2) (155.9(1)
and 155.4(1) pm) are in the expected range (d(SiÀF): 156.7 pm
29
19
À908C. The Si{ F} DEPT NMR
[
8]
[11]
in (C F ) SiF, d(SÀF): 156 pm in SiF ). The F-Si-F angle of
spectrum is characterized by
2
5 3
4
1
10.98 is only slightly reduced in comparison to the C-Si-C
a quintet at d=À21.7 ppm with
2
angle of 108.18 and close to the ideal tetrahedral angle of
a
4
J(Si,F) coupling constant of
7.8 Hz. In comparison to 4 and 5,
Figure 4. Molecular structure
of 6; 50% probability ampli-
tude displacement ellipsoids
are shown; selected bond
the
molecular
structure
of
(
C F ) SiBr (6) (Figure 4) in the
2
5 2
2
crystal exhibits a different confor- lengths [pm] and angles [8]:
SiÀBr1: 215.4(1), SiÀC1:
mer for the two pentafluoroethyl
1
92.6(5); C1-Si-C1’: 114.1(3),
groups, presumably due to the
obtuse C-Si-C angle of 114.18. The
SiÀBr bond length of 215.4 pm is
in the expected range of bromosi-
Br1-Si-Br1’: 113.4(1), Br1-Si-C1:
05.1(2)8.
1
Figure 2. Molecular structure of (C
displacement ellipsoids are shown; selected bond lengths [pm] and angles
8]: SiÀF1: 155.9(1), SiÀF2: 155.4(1), SiÀC1: 191.1(1), SiÀC3: 191.0(1); C1-Si-C3:
08.1(1), F1-Si-F2: 110.9(1).
2 5 2 2
F ) SiF (4); 50% probability amplitude
[14]
[
1
lanes.
IR spectroscopy
109.58 In contrast, the molecular structure of the dihydrosilane
5
(Figure 3) exhibits significantly different H-Si-H and C-Si-C
Figure 5 and Table 1 compile selected data of the IR data of si-
lanes 3–6 in the gas phase. In Figure 2 relevant absorption
bands are assigned to vibrational modes. Table 1 allows a com-
parison between measured and calculated data. The quantum
chemical calculations were carried out with a DFT method on
the B3LYP level employing the 6-311G(d,p) basis set.
angles of 113 and 103.08, respectively. A large H-Si-H angle
compared to a C-Si-C angle of two sterically demanding C F
2
5
[
12]
[13]
groups may surprise, but is consistent with BENT’s rule.
The hydrogen substituents exhibit a lower electronegativity
than the C F groups. Hence they induce an increased s-orbital
2
5
character in the SiÀH bonds that affects a widening of the H-
Si-H angle to 1138. As a consequence, the increased p-orbital
character of the SiÀC bonds compresses the C-Si-C angle to
103.08.
Figure 3. Molecular structure of (C
2 5 2 2
F ) SiH (5); 50% probability amplitude
displacement ellipsoids are shown; selected bond lengths [pm] and angles
[
8]: SiÀH1: 134(2), SiÀC1: 192.8(1); C1-Si-C1’: 103.0(1), H1-Si-H1’: 113(2).
The protocol for the synthesis of (C F ) SiCl (3) cannot be
2
5 2
2
extended to the corresponding dibromo derivative. Reaction
of 2 with various acyl bromides invariantly led to intractable
mixtures. In contrast to this, the reaction of 5 with a slight
excess of bromine in 1,6-dibromohexane solution smoothly
furnished product (C F ) SiBr in 93% yield (Scheme 7).
2
5 2
2
After separation by fractional condensation, crude dibromo-
bis(pentafluoroethyl)silane (6) was treated with mercury to
remove traces of bromine. Finally, the product was isolated as
Figure 5. IR spectra of 5 (top), 4 (upper middle), 3 (lower middle), and
6 (bottom).
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[
a]
Table 1. Gas-phase IR data of the synthesized (C
2
F
5
)
2
SiX
2
derivatives.
[
c]
R
2
SiBr SiCl SiF R SiH
2
R
2
2
R
2
2
2 2
[
b]
[b]
[b]
[b]
Exptl. Calcd Exptl. Calcd Exptl. Calcd Exptl. Calcd Assignment
1
1
1
332 1303
311 1297
1342 1309
1312 1295
1362 1318
1315 1302
1351
1318
1318
1306
1223/
1216
1143
1135
994/
979
n
n
n
s
CC
asCC
229 1220/ 1229 1225/ 1230 1233/ 1227
s+asCF, CF
3
1208
1218
1142 1135
1111 1133
1223
1158 1152
1116 1095
1004 997/
993
753 740
1004/ 976/
895 872
1137 1126
1147
1108
995
n
n
n
s 2
CF,CF
1
110
1099
984/
asCF,CF
2
984
990
984/
974
746
as+sSiC
Scheme 8. Reaction of bis(pentafluoroethyl)silanes with 1,10-phenanthroline
yielding the corresponding phenanthroline adducts.
967
7
5
4
46
45/
92
746
524/
483
753
743
739
dCF
3
607/ 597/
2249/ 2304/
2231 2283
n
as+sSiX
577
566
À1
shifts between d= +10 to À75 ppm. Coordination of a chelat-
[
a] Wavenumbers in cm . [b] B3LYP/6-311G(d,p). [c] dSiH
2
2
: 913, wSiH : 810;
calcd: 924, 811.
ing phenanthroline ligand forming an octahedral silicate com-
29
plex has an eminent influence on the Si NMR chemical shift.
These compounds reveal chemical shifts for the central silicon
À1
19
The vibrational bands at about 1300 cm correspond to C–
C stretching modes, whereby asymmetrical vibration is clearly
more intensive than the symmetrical one. Apart from the SiÀH
bond of silane 5 this stretching mode exhibits the highest
wavenumber. The most intensive bands are caused by the
atoms below d=À150 ppm. The F NMR resonances of the
phenanthroline complexes are shifted downfield compared to
the corresponding silanes. This effect is considerably more pro-
nounced for the CF2 groups than for the CF3 groups. The
2
J(Si,F) coupling constants are comparable to those of the si-
symmetrical and asymmetrical C–F stretching vibrations of the
lanes and do not differ significantly. Comparison of the difluor-
À1
CF groups at approximately 1220 cm . Noticeably, the bands
3
osilane 4 and the corresponding phenanthroline adduct 9 re-
19
of the related vibrations of the CF units are of lower intensity.
veals a peculiarity. The F NMR resonance of the fluorine
atoms directly connected to the silicon atom shift significantly
2
For the halogen-substituted silanes (X=F, Cl, Br) a clear
trend is obtained. An increasing electronegativity of the halo-
gen substituents leads to increasing energies for the character-
istic vibrational modes. This is especially evident for the Si–X
streching modes, but also applicable to the symmetric and an-
tisymmetric CCÀ, as well as CFÀ valence modes of the penta-
fluoroethyl groups.
1
(d=À150.6 (4) and À128.8 ppm (9)). Furthermore, the J(Si,F)
coupling constants decrease significantly from 353 (4) to
1
13
258 Hz (9). H and C NMR data are comparable to free 1,10-
phenanthroline.
Table 2 gives an overview of the characteristic NMR spectro-
scopic data collected for the synthesized bis(pentafluoroethyl)-
silanes and their adducts with 1,10-phenanthroline.
Bis(pentafluoroethyl)silane adducts with N bases
The silicon atom in bis(pentafluoroethyl)silanes is characterized
by an inherently high Lewis acidity. Consistently, a wide variety
of donor species forms adducts with these kinds of silanes. In
general, such adducts are stable in the solid state and are iso-
2 5 2 2
Table 2. NMR data of (C F ) SiR and substrates.
2
9
2
19
19
Si
J(Si,F)
F(CF
3
)
2
F(CF )
Cl
2
Si(OPh)
2
1
2
3
4
5
6
7
8
À63.3
À72.5
À14.0
À59.3
À40.6
À21.7
[
a]
(
(
C
C
2
F
F
5
)
)
2
2
Si(OPh)
2
41.5
45.3
46.3
34.3
47.8
38.5
45.3
35.3
50.2
À82.9
À82.1
À84.8
À85.1
À81.0
À81.3
À80.1
À82.7
À80.5
À129.3
À127.4
À132.4
À124.4
À125.0
À119.1
À114.4
À125.8
À112.5
[
15]
lated in good yields. Kummer et al. investigated Lewis donor
acceptor adducts of amine bases and different silane deriva-
[a]
2
5
SiCl
2
[
a,b]
(C F ) SiF
(C
2
2
2
5
5
5
2
2
2
2
[
16]
[a]
tives. The complex stability of a silane adduct increases in
the order pyridine<bipyridine<1,10-phenanthroline. Keeping
this in mind, we investigated the acceptor behavior of the syn-
thesized silanes towards 1,10-phenanthroline.
F
F
)
)
SiH
2
[
a]
(
[
[
C
Si(C
Si(C
SiBr
2
[c]
2
2
F
F
5
)
)
2
(OPh)
Cl
2
(phen)]
À175.5
À165.5
À171.6
À179.7
[c]
5
2
2
(phen)]
[
c,d]
[Si(C F ) F (phen)]
[Si(C
2
5
2
2
9
10
[
c]
Silanes 2–6 react with 1,10-phenanthroline in acetonitrile or
dichloromethane within 1–3 h and the corresponding adducts
2
F
5
)
2
Br
2
(phen)]
19
1
[
a] Neat compound. [b] (C
2
F
5
)
2
SiF
2
:
d( FÀSi)=À150.6 ppm, J(Si,F)=
SiF
(phen)]: d( FÀSi)=À128.8 ppm,
1
9
7
–10 (Scheme 8) are formed in excellent yields. All adducts are
353 Hz. [c] In acetonitrile. [d] [(C
1
2
F
5
)
2
2
J(Si,F)=258 Hz.
moderately soluble in acetonitrile and nearly insoluble in di-
chloromethane, ethanol, and pentane.
NMR spectroscopy
X-ray structure determination
For pentafluoroethyl-substituted silicon compounds shift
Single crystals of the phenanthroline adducts were grown
from cold acetonitrile solution or mixtures of acetonitrile and
dichloromethane and analyzed by X-ray diffraction. The molec-
ular structures are shown in Figures 6–8. The C F groups ex-
29
ranges in Si NMR spectra correlate nicely with the coordina-
tion number of the Si atom. The tetrahedrally coordinated sili-
con atoms in bis(pentafluoroethyl)silanes exhibit chemical
2
5
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À3
13
1
·10 mbar. According to C NMR spectra this product is a 1:2
complex of (C F ) Si(O CCF ) and acetonitrile.
2
5 2
2
3 2
29
The Si NMR spectrum of [Si(C F ) (O CCF ) (NCCH ) ] (11) re-
2
5 2
2
3 2
3 2
veals a quintet at d=À196.4 ppm which is characteristic for an
octahedrally coordinated silicon atom in bis(pentafluoroethyl)-
2
silicon compounds with a J(Si,F) coupling constant of 44 Hz.
19
In the F NMR spectrum, the fluorine atoms of the trifluoroa-
cetoxy group (d=À76.8 ppm) are shifted downfield compared
to the CF groups of the pentafluoroethyl substituents (d=
3
À81.9 ppm).
2 5 2 2
Figure 6. Molecular structure of [Si(C F ) (OPh) (phen)] (7); 50% probability
Vibrational spectroscopy confirms the synthesis of 11. Char-
acteristic vibrational modes for symmetrical and antisymmetri-
cal carbon nitrogen stretching modes of the acetonitrile li-
amplitude displacement ellipsoids are shown; H-atoms bonded to carbon
omitted for clarity; selected bond lengths [pm] and angles [8]: SiÀO1:
1
68.5(1), SiÀO2: 169.2(1), SiÀN1: 201.6(1), SiÀN2: 202.9(1); N1-Si-N2: 79.1(1),
À1
O1-Si-O2 105.0(1).
gands show resonances at 2340 and 2311 cm , respectively.
Valence modes for the carbonyl functionality exhibit intensive
À1
vibrational bands at about 1767 cm . The most intensive
À1
bands at 1149 and 1117 cm are ascribable to the C–F vibra-
tional modes of the CF groups (O CCF +C F ) and the CF
2
3
2
3
2
5
groups (C F ), respectively. Single crystals of 11 could be ob-
2
5
tained from a dichloromethane solution at À288C (Figure 9).
The solid-state structure of the acetonitrile adduct 11 reveals
the picture of a slightly distorted octahedral structure with two
pentafluoroethyl groups in trans position. In contrast to this,
cis orientation of the trifluoroacetoxy and the trimethylcyanido
ligands is preferred. The strong widening of the O1-Si-O1’
angle (101.1(2)8) is remarkable, but presumably may be due to
the spatial demand of the trifluoroacetoxy groups.
2 5 2 2
Figure 7. Molecular structure of [Si(C F ) Cl (phen)] (8) 50% probability am-
plitude displacement ellipsoids are shown; H-atoms bonded to carbon omit-
ted for clarity; selected bond lengths [pm] and angles [8]: SiÀCl1: 216.6(1),
SiÀCl2: 215.3(1), SiÀN1: 199.2(1), SiÀN2: 200.3(1); N1-Si-N2: 81.0(1); Cl1-Si-
Cl2: 94.2(1).
Figure 9. Molecular structure of [Si(C
2 5 2 2 3 2 3 2
F ) (O CCF ) (NCCH ) ] (11); 50% proba-
bility amplitude displacement ellipsoids are shown; selected bond lengths
2 5 2 2
Figure 8. Molecular structure of [Si(C F ) F (phen)] (9); 50% probability am-
[
pm] and angles [8]: SiÀO1: 173.0(3), SiÀN1: 195.4(3); N1-Si-N1’: 87.4(2), C1-Si-
plitude displacement ellipsoids are shown; H-atoms bonded to carbon omit-
ted for clarity; selected bond lengths [pm] and angles [8]: SiÀF1: 164.4(1),
SiÀF2: 164.2(1), SiÀN1: 199.4(1), SiÀN2: 198.9(1); N1-Si-N2: 80.6(1), F1-Si-F2:
C1’: 165.9(2), O1-Si-O1’: 101.1(2).
98.1(1).
Conclusion
We have successfully devised a convenient protocol for the
synthesis of bis(pentafluoroethyl)silanes on a multigram scale.
A key step for this is the employment of (PhO) SiCl in which
hibit a trans disposition at the six-coordinated Si atom. The
two substituents X are cis-oriented in a joint plane with the
chelating ligand. Whereas bond lengths and angles on the
Si(C F ) axis are comparable, bond angles within the SiN X
2
2
the Lewis acidity of the Si centre is mitigated by the p-donat-
ing phenoxy groups. Consistently, the replacement of chlorine
atoms by two C F groups was smoothly effected without fluo-
2
5 2
2 2
unit differ considerably.
2
5
Dichlorosilane 3 reacts with trifluoroacetic acid forming bis(-
pentafluoroethyl)bis(trifluoroacetoxy)silane and HCl. After
evaporation of the volatile compounds a colorless solid could
be obtained that is highly sensitive towards moisture. The
crude product is purified by sublimation at 208C and
ride transfer from LiC F . The phenoxy groups are cleanly re-
2 5
placed by two chlorine atoms during reaction with carboxylic
acid chlorides in the presence of a FeCl catalyst. The substitu-
3
tion of the chlorides in (C F ) SiCl by various nucleophiles pro-
2
5 2
2
vides access to a plethora of bis(pentafluoroethyl)silanes. As
Chem. Eur. J. 2016, 22, 1 – 9
www.chemeurj.org
5
ꢀ 2016 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
&
&
These are not the final page numbers! ÞÞ

Full Paper
the introduction of pentafluoroethyl functionalities into silicon
compounds enhances the Lewis acidity of the resulting spe-
cies, the synthesis of previously inaccessible hypervalent silicon
derivatives is feasible. Due to the Lewis acidity, complex forma-
tion to a series of hexacoordinate adducts with 1,10-phenan-
throline is rendered possible. The bonding situations in the
novel compounds were elucidated by spectroscopic means
and X-ray analyses.
Synthesis of dichlorobis(pentafluoroethyl)silane (3): The reaction
was performed in a sealed ampoule. Phenylacetyl chloride (55.28 g,
3
1
57.6 mmol) was added to solid iron(III) chloride (248 mg,
.53 mmol). After the addition of bis(pentafluoroethyl)diphenoxysi-
lane (2) (24.20 g, 53.54 mmol), the degassed solution was stirred
for 5 h at rt. Product 3 and other volatile components were sepa-
rated under dynamic vacuum conditions by fractional condensa-
tion through two traps at À40 and À1968C. The À1968C trap con-
tains 3 and HCl, which was separated at À1008C. Compound 3
was obtained as a colorless liquid with a vapor pressure of
8
6 mbar at room temperature and a melting point of À1358C in
13
1
9
6% yield (17.26 g, 51.39 mmol). C{ H} NMR (75.47 MHz, neat,
Experimental Section
1
2
[
D ]acetone): d=113.2 (t, q, J(C,F)=276.1, J(C,F)=43.1 Hz, ÀCF À),
6
2
1
2
13 19
Materials and apparatus
118.9 ppm (q, t, J(C,F)=285.1, J(C,F)=29.6 Hz, CF À); C{ F} NMR
3
(
75.47 MHz, neat, [D ]acetone): d=113.2 (s, ÀCF À), 118.9 ppm (s,
6
2
All reactions were carried out under an atmosphere of dry nitrogen
using standard Schlenk techniques. Chemicals were obtained from
commercial sources and used without further purification. NMR
spectra were recorded on a Bruker Avance III 300 spectrometer
19
CF À); F NMR (282.40 MHz, neat, [D ]acetone): d=À82.1 (s, CF À),
3
6
3
29
À127.4 ppm (s, ÀCF À); Si NMR (59.63 Hz, neat, [D ]acetone): d=
2
6
2
29
19
À13.8 ppm (quint, J(Si,F)=47.1 Hz, (C F ) SiCl );
Si{ F} NMR
SiCl ); IR (gas
2
5 2
2
2
9
19
13
1
(59.63 Hz, neat, [D
6
]acetone): d=À13.8 ppm (s, (C
F
2
)
5
2
2
(
Si: 59.6 MHz; F: 282.4 MHz; C: 75.5 MHz; H: 300.1 MHz) with
phase): n˜ =1342 (w, n (CC), C F ), 1312 (m, n (CC), C F ), 1232 (s,
s
2
5
as
2 5
positive shifts being downfield from the external standards
2
9
13
1
19
n
s+as(CF), CF
3
), 1142 (m, n (CF), CF ), 1111 (m, nas(CF), CF ), 990 (m,
s 2 2
(
TMS( Si), ( C) and ( H), and CCl F ( F)). IR spectroscopic measure-
3
nas+s(SiC)), 753 (w, d(CF )), 664 (m, n (SiCl)), 623 (w, d(CF )+
3
as
2
ments were conducted on a Bruker Alpha-FTIR spectrometer. For
liquids and solid-state materials we used an ATR element from
Bruker; gas-phase spectra were collected using a teflon gas cell
with KBr windows. EI mass spectra were recorded with a Micromass
VG Autospec X magnetic sector mass spectrometer (20 eV) with
a standard EI source. Volatile compounds were introduced by
a gas-phase inlet. Intensities are referenced to the most intense
peak of a group. C, H, N analyses were carried out with a HEKAtech
Euro EA 3000 apparatus.
À1
n (SiCl)), 607 (w, d(CF )+n (SiCl)), 577 (w, n (SiCl)), 459 cm (w,
s
2
as
s
d(SiCl)).
Synthesis of difluorobis(pentafluoroethyl)silane (4): In a sealed
ampoule antimony trifluoride (5.34 g, 30.0 mmol) was stirred for
9
lane (3.37 g, 10.0 mmol). Product 4 was separated under dynamic
vacuum conditions by fractional condensation through two traps
at À60 and À1968C. The À1968C trap contains difluorosilane 4,
which was obtained as a colorless liquid with a vapor pressure of
0 min at rt in an atmosphere of bis(pentafluoroethyl)dichlorosi-
Synthetic methods
3
15 mbar at room temperature in 97% yield (2.95 g, 9.70 mmol).
13
19
[
9]
M.p. À1358C; C{ F} NMR (75.47 MHz, neat, [D
]acetone): d=112.3
6
Synthesis of dichlorodiphenoxysilane (1): A solution of silicon
tetrachloride (93.3 g, 549 mmol) in diethyl ether (350 mL) was com-
bined with a solution of phenol (108 g, 1.15 mol) in diethyl ether
19
(
[
s, ÀCF À), 118.4 ppm (s, CF À); F NMR (282.40 MHz, neat,
2
3
D ]acetone): d=À84.7 (s, CF À), À132.5 (s, ÀCF À), À150.5 ppm (s,
6
3
2
29
SiF ); Si NMR (59.63 Hz, neat, [D ]acetone): d=À59.3 (t, quint,
2
6
(
200 mL) and the mixture was stirred at rt for 2 d. After evapora-
1
2
J(Si,F)=352.9, J(Si,F)=45.6 Hz, (C F ) SiF ); IR (gas phase): n˜ =
2
5 2
2
tion of the solvent, 1 was obtained by vacuum distillation
À3
1362 (w, n (CC), C F ), 1315 (s, n (CC), C F ), 1230 (vs, ns+as(CF), CF3),
s 2 5 as 2 5
(
4
1·10 mbar) at 1008C as a colorless liquid in 73% yield (114 g,
1
1158 (s, n (CF), CF ), 1116 (m, n (CF), CF ), 1004 (m, nas+s(SiC)), 895
s 2 as 2
01 mmol). H NMR (300.13 MHz, neat, [D ]acetone): d=6.4–
6
29
(m, n (SiF)), 855 (w), 753 (w, d(CF )), 616 (w, d(CF )), 590 (w, d(CF )),
s 3 2 3
6
.6 ppm (m, PhÀH); Si NMR (59.63 Hz, neat, [D ]acetone): d=
6
À1
5
62 (w), 489 (w, d(SiF)), 398 cm (w, d(SiF)).
À63.3 ppm (m, Cl Si(OPh) ).
2
2
Synthesis of bis(pentafluoroethyl)silane (5): In a sealed ampoule
bis(pentafluoroethyl)dichlorosilane (3) (4.64 g, 17.3 mmol) was con-
densed to a degassed solution of tributyltin hydride (11.3 g,
Synthesis of bis(pentafluoroethyl)diphenoxysilane (2): A 1.6m n-
butyllithium solution in n-hexane (129.07 g, 189.81 mL,
3
03.73 mmol) was dissolved in diethyl ether (350 mL) and de-
3
8.9 mmol). The mixture was stirred for 17 h at rt. Product 5 and
gassed at À908C. The solution was stirred for 30 min at À858C in
other volatile components were separated under dynamic vacuum
conditions by fractional condensation through two traps at À65
and À1968C. The À1968C trap contains product 5, which was ob-
tained as a colorless liquid in 99% yield (4.73 g, 17.1 mmol). Vapor
an atmosphere of C F H (313.70 mmol). While stirring for 30 min
2
5
the temperature was slowly raised to À608C. After addition of di-
chlorodiphenoxysilane, Cl Si(OPh) , (1), (52.15 g, 151.9 mmol) at
2
2
À608C, the mixture was warmed to rt and stirred overnight. A col-
1
pressure: 380 mbar (rt); m.p. À958C; H NMR (300.13 MHz, neat,
orless precipitate was filtered off. After evaporation of the solvent,
1
3
19
À3
[
[D
D ]acetone): d=4.8 ppm (m, SiH ); C{ F} NMR (75.47 MHz, neat,
compound 2 was obtained by vacuum distillation (1·10 mbar) at
6
2
2
1
6
78C as a colorless liquid in 74% yield (51.07 g, 113.0 mmol).
6
]acetone): d=116.5 (t, J(C,H)=7.4, J(C,Si)=74.5 Hz, ÀCF
À); F NMR (282.40 MHz, neat,
(s, J(F,C)=279.4 Hz, CF
À),
2
À),
1
2
19
H NMR (300.13 MHz, neat, [D ]acetone): d=6.7 (m, 3H, meta-H,
para-H), 6.8 (m, 2H, ortho-H); C{ H} NMR (75.47 MHz, neat,
119.4 ppm (s, J(C,Si)=7.4 Hz, CF
[D ]acetone):
d=À82.1 ppm
3
6
13
1
1
6
3
1
2
2
1
29
[
1
1
D ]acetone): d=113.9 (t, q, J(C,F)=275.7, J(C,F)=45.2 Hz, ÀCF À),
À124.5 ppm (t, J(F,H)=9.7, J(F,C)=270.7 Hz, ÀCF À); Si NMR
2
6
2
1
2
18.6 (s, meta-C), 118.9 (q, t, J(C,F)=284.9, J(C,F)=29.7 Hz, CF À),
(59.63 Hz, neat, [D
6
]acetone): d=À40.6 ppm (t, quint, sept,
3
19
1
2
1
2
3
24.1 (s, para-C), 129.4 (s, ortho-C), 150.8 ppm (s, ipso-C); F NMR
J(Si,H)=242.9,
J(Si,F)=35.3,
J(Si,F)=1.2 Hz,
(C F ) SiH );
2 5 2 2
9
19
(
282.40 MHz, neat, [D ]acetone): d=À82.9 (s, CF À), À129.3ppm (s,
Si{ F} NMR (59.63 Hz, neat, [D
6
]acetone): d=À40.6 ppm (t,
J(Si,H)=242.9, J(Si,C)=74.5, J(Si,C)=7.2 Hz, (C SiH ); IR (gas
(SiH)), 1351 (w, n (CC)),
1318 (s, n (CC)), 1227 (vs, n (CF), CF ), 1147 (s, n (CF), CF ), 1108
6
3
2
9
1
2
ÀCF À); Si NMR (59.63 Hz, neat, [D ]acetone): d=À72.5 ppm
2
F
5
)
2
2
2
6
2
29
19
(
quint, J(Si,F)=41.5 Hz, (C F ) Si(OPh) ); Si{ F} NMR (59.63 Hz,
phase): n˜ =2249 (m, nas(SiH)), 2231 (m, n
s
s
2
5 2
2
neat, [D ]acetone): d=À72.5 ppm (s, (C F ) Si(OPh) ).
6
2
5 2
2
as
s+as
3
s
2
&
&
Chem. Eur. J. 2016, 22, 1 – 9
www.chemeurj.org
6
ꢀ 2016 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
ÝÝ These are not the final page numbers!

Full Paper
(
m, n (CF), CF ), 1092 (m, n (CF), CF ), 995 (m, ns+as(SiC)), 913 (m,
gassed solution of 1,10-phenanthroline (230 mg, 1.27 mmol) in ace-
tonitrile (6 mL). After the mixture had been stirred for 20 h at rt,
acetonitrile was removed under reduced pressure. Product 9 was
obtained after recrystallization from acetonitrile (2 mL) at À288C as
as
2
as
2
d(SiH )), 810 (s, d(SiH )), 743 (m, d(CF )), 608 (w, d(CF )+d(SiH)), 590
(
2
2
3
2
À1
w, d(CF )), 533 (w, d(CF )), 515 (w, d(SiH)), 409 (w), 385 cm (m).
2 3
1
9
Synthesis of dibromobis(pentafluoroethyl)silane (6): In a sealed
ampoule bromine (3.1 mL, 59.3 mmol) was dissolved in 1,6-dibro-
mohexane (35 mL). After degassing, bis(pentafluoroethyl)silane (5)
a colorless solid in 28% yield (0.17 g, 0.35 mmol). F NMR
(282.40 MHz, neat, [D
]acetone): d=À80.1 (m, CF
À), À126.0 (m, À
6
3
29
CF À), À129.1 ppm (m, ÀSiF );
Si NMR (59.63 Hz, neat,
2
2
1
2
(
6.48 g, 24.2 mmol) was condensed onto the solution. The reaction
[D ]acetone): d=À170.9 ppm (t, quint, J(Si,F)=257.7, J(Si,F)=
6
29
19
mixture was slowly warmed to rt and stirred for 16 h. Evaporated
HBr was separated in a trap at À658C. Remaining volatile com-
pounds were condensed onto elemental mercury and stirred for
36.5 Hz,
(C F ) SiF(phen));
Si{ F} NMR
(59.63 Hz,
neat,
2
5 2
[D ]acetone): d=À170.9 (s, (C F ) SiF (phen)); elemental analysis
6
2
5 2
2
calcd (%) for C H F N Si (M=484.03): C 39.68, H 1.66, N 5.78;
16
8
12
2
1
h at room temperature. The pure product was isolated from mer-
cury and mercury salts via condensation. Silane 6 was obtained in
3% yield (9.49 g, 22.4 mmol); Vapor pressure: 28 mbar (rt); m.p.
found: C 39.37, H 1.72, N 5.83; IR (ATR): n˜ =3112 (vw, n(CH)), 1622
(w, n(C=C)), 1584 (w, n(C=N)+n(C=C)), 1530 (w, d(CH)), 1438 (m,
d(CH)), 1323 (m, n (CC), C F ), 1307 (m, n (CC), C F ), 1198 (s, n(CF),
9
s
2
5
as
2 5
1
9
À908C; F NMR (282.40 MHz, neat, [D ]acetone): d=À81.0 (s, CF À
CF ), 1177 (s, n(CF), CF ), 1151 (s, d(CH)), 1117 (s, n (SiC)), 1109 (s,
3 3 as
6
3
29
19
)
,
À125.0 ppm (s, ÀCF À);
Si{ F} NMR (59.63 Hz, neat,
2
n (SiC)), 1028 (s, n(CF), CF ), 955 (m, n (CC), C F ), 947 (m, n (CC),
s 2 s 2 5 s
2
[
D ]acetone): d=À21.7 ppm (quint., J(Si,F)=47.8 Hz, (C F ) SiBr );
6
2
5 2
2
C F ), 880 (m, d(C=C)+d(CH)), 856 (s, d(CH)), 771 (s, n(SiF)), 756 (s,
2 5
IR (gas phase): n˜ =1332 (w, n (CC), C F ), 1311 (s, n (CC), C F ), 1229
s
2
5
as
2
5
d(CH)), 724 (vs, d(C F )), 564 (s), 528 (m, d(C F )), 488 (s), 452 (m),
2 5 2 5
(
(
vs, ns+as(CF), CF ), 1137 (s, n (CF), CF ), 1110 (m, n (CF), CF ), 984
m, ns+as(SiC)), 895 (vw), 752 (w, d(CF )), 622 (w, d(CF )), 591 (w,
À1
3
s
2
as
2
432 (s), 404 cm (w, d(SiF).
3
2
d(CF )), 545 (m, n (SiBr)), 492 (m, n (SiBr)), 459 (w, d(SiBr)), 447 (w,
3
as
s
Synthesis of [Si(C F ) Br (phen)] (10): 1,10-Phenanthroline
2
5
2
2
À1
d(C F )), 426 cm (w, d(C F )).
2
5
2
5
(155 mg, 0.86 mmol) was dissolved in dry dichloromethane. The
colorless solution was degassed and treated with dibromobis(pen-
tafluoroethyl)silane (6) (373 mg, 0.88 mmol) resulting in a colorless
suspension that was stirred for 3 h at rt. After evaporation of the
solvent, dry ethanol was condensed to the colorless solid to
remove unreacted 1,10-phenanthroline. After filtration the product
Synthesis of [Si(C F ) (OPh) (phen)] (7): Bis(pentafluoroethyl)-di-
2
5
2
2
phenoxysilane (2) (1.40 g, 3.09 mmol) was added to a solution of
,10-phenanthroline (0.56 g, 3.10 mmol) in acetonitrile (8 mL). After
1
the mixture had been stirred for 3 h at rt, solvents were removed
under reduced pressure. Pure product 7 was obtained after recrys-
tallization from acetonitrile (4 mL) at À288C as a yellow solid in
was obtained as
a colorless solid in 55% yield (287 mg,
19
0
.47 mmol). F NMR (282.40 MHz, neat, [D ]acetone): d=À79.7 (s,
6
1
9
9
[
(
3
1% yield (1.78 g, 2.81 mmol).
F NMR (282.40 MHz, neat,
29
CF À), À111.7 ppm (s, ÀCF À);
Si NMR (59.63 Hz, neat,
3
2
29
D ]acetone): d=À81.3 (s, CF À), À119.1 ppm (s, ÀCF À); Si NMR
2
6
3
2
[
(
(
D ]acetone):
d=À179.7 ppm
(quin,
J(Si,F)=50.4 Hz,
6
2
59.63 Hz, neat, [D ]acetone): d=À178.5 ppm (quint, J(Si,F)=
6
C F ) SiBr (phen)); elemental analysis calcd (%) for C H Br F N Si
M=606.13): C 31.70, H 1.33, N 4.62, Br 26.37; found: C 34.02, H
.97, N 4.97; IR (ATR): n˜ =3098 (w, n(CH)), 2924 (w, n(CH)), 2853 (w,
2
5 2
2
16
8
2
10
2
29
19
8.5 Hz, (C F ) Si(OPh) (phen));
Si{ F} NMR (59.63 Hz, neat,
2
5 2
2
[
D ]acetone): d=À178.5 ppm (s, (C F ) Si(OPh) (phen)); elemental
6
2
5 2
2
1
analysis calcd (%) for C H F N O Si (M=633.52): C 53.17, H 2.87,
28
18 10
2
2
n(CH)), 1618 (w, n(C=C)), 1585 (w, n(C=N)+n(C=C)), 1527 (m,
N 4.43; found: C 52.82, H 2.91, N 4.33; IR (ATR): n˜ =3113 (vw,
n(CH)), 1597 (m, n(C=C), phen), 1586 (m, n(C=C), phen), 1526 (m,
n(C=N)+n(C=C)), 1438 (m, d(CH)), 1307 (m, n (CC), C F ), 1295 (m,
d(CH)), 1494 (w, d(CH)), 1430 (m, n(C=C)+d(CH)), 1297 (m, n (CC),
s
C F ), 1284 (m, n (CC), C F ), 1210 (m, n (CF), CF ), 1168 (vs, n (CF),
2
5
as
2
5
s
3
as
s
2 5
CF ), 1099 (s, n (CF), CF ), 1037 (s, n (CF), CF ), 963 (s, d(CF )), 935
3
as
3
s
2
2
n (CC), C F ), 1198 (s, n(CF), CF ), 1177 (s, n(CF), CF ), 1117 (s, n (CF),
as
2
5
3
3
as
(w), 875 (m, d(C=C)), 848 (s, d(CH)), 780 (w), 745 (m, d(CH)), 720 (s,
CF ), 1028 (s, n (CF), CF ), 952 (m, n (SiC)), 944 (m, n (SiC)), 931 (w,
2
s
2
as
s
d(CF )), 645 (m, d(C=C)), 615 (m, d(C F )), 589 (m, d(C F )), 545 (m,
3
2
5
2 5
n(SiO)), 912 (w, n(SiO)), 734 (m, d(CF )), 724 (w, n(SiO)), 564 (w,
3
À1
d(SiN)), 472 (s), 457 (s), 434 (s), 422 (s), 404 (vs, n (SiBr)), 389 cm
À1
s
d(C F )), 432 cm (w).
2
5
(
vs, n (SiBr)).
as
Synthesis of [Si(C F ) Cl (phen)] (8): Dichlorobis(pentafluoroethyl)-
silane (3) (668 mg, 2.20 mmol) was condensed onto a degassed so-
lution of 1,10-phenanthroline (360 mg, 1.99 mmol) in acetonitrile
2
5 2
2
Synthesis of [Si(C F ) (O CCF ) (NCCH ) ] (11): A mixture of tri-
2
5 2
2
3
2
3 2
fluoroacetic anhydride and trifluoroacetic acid (474 mg, 4.16 mmol)
was dissolved in acetonitrile (15 mL). Dichlorobis(pentafluoroethyl)-
silane, 3, (682 mg, 2.03 mmol) was condensed onto the solution
and warmed to rt while stirring. After evaporation of the volatile
compounds, a colorless solid was obtained. Sublimation gave the
(
8 mL). After the mixture had been stirred for 1 h at rt, acetonitrile
was removed under reduced pressure. The product 8 was obtained
after recrystallization from acetonitrile (2 mL) at À288C as a color-
19
less solid in 59% yield (530 mg, 1.17 mmol); F NMR (282.40 MHz,
19
product in 70% yield (816 mg, 1.42 mmol). F NMR (282.40 MHz,
neat, [D ]acetone): d=À79.9 (s, CF À), À114.1 ppm (s, ÀCF À);
6
3
2
2
2
9
neat, [D
6
]acetone): d=À76.8 (s, ÀO
2
CCF
3
), À81.9 (s, ÀCF
),
3
Si NMR (59.63 Hz, neat, [D ]acetone): d=À165.5 ppm (quint,
6
29
29
19
À123.6 ppm (s, ÀCF
2
À); Si NMR (59.63 Hz, neat, [D
6
]acetone): d=
J(Si,F)=45.3 Hz, (C F ) SiCl (phen)); Si{ F} NMR (59.63 Hz, neat,
2
5 2
2
2
À196.4 ppm (quin, J(Si,F)=44 Hz, [Si(C F ) (O CCF ) (NCCH ) ]); IR
2
5 2
2
3 2
3 2
[
D ]acetone): d=À165.5 ppm (s, (C F ) SiCl (phen)); elemental anal-
6
2
5 2
2
(
2
ATR): n˜ =3015 (vw, n(CH )), 2944 (w, n(CH )), 2340 (m, n (CꢀN)),
3
3
s
ysis calcd (%) for C H C F N Si (M=517.22): C 37.10, H 1.56, N
1
6
8
l2 10
2
311 (w, n (CꢀN)), 1767 (s, n +n (C=O)), 1398 (m, n (C-C), TFA+
as
as
s
s
5
1
.42; found: C 37.24, H 1.62, N 5.51; IR (ATR): n˜ =3108 (vw, n(CH)),
619 (w, n(C=C)), 1586 (w, n(C=N)+n(C=C)), 1432 (m, d(CH)), 1293
d(CH )), 1386 ((m, n (CÀC), TFA+d(CH )), 1306 (m, n +n (CÀC),
3
as
3
s
as
C F ), 1181 (s, n (CF), CF ), 1149 (vs, n(CF), CF , TFA+n(CF), CF ,
2
5
s
3
3
3
(
m, b, n(CC), C F ), 1207 (s, n (CF), CF ), 1168 (vs, n (CF), CF ), 1098
2 5 as 3 s 3
C F ), 1117 (vs, n +n (CF), CF ), 1053 (s, n(CF), CF +d(CH )), 968
2
5
s
as
2
2
3
(
4
s, n (CF), CF ), 1024 (s, n (CF), CF ), 747 (s, d(CF )), 564 (s, d(C F )),
as 2 s 2 3 2 5
18 cm (w).
À1
(m, n (SiC)+n (C=C)), 858 (m, d(CO )), 777 (w), 751 (w), 725 (w),
as s 2
À1
6
10 (m), 557 (s), 483 (m), 428 (s), 402 cm (m).
Synthesis of [Si(C F ) F (phen)] (9): Bis(pentafluoroethyl)difluorosi-
2
5 2 2
lane (4) (435 mg, 1.43 mmol) was condensed at À1968C onto a de-
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X-ray structure determination
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Published online on && &&, 0000
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FULL PAPER
&
Silicon Chemistry
N. Schwarze, B. Kurscheid, S. Steinhauer,
B. Neumann, H.-G. Stammler, N. Ignat’ev,
B. Hoge*
&& – &&
Synthesis of Functional
Bis(pentafluoroethyl)silanes
(C F ) SiX , with X=H, F, Cl, Br, OPh,
Hypervalent silicon: The introduction
of pentafluoroethyl functionalities into
silicon compounds enhances the Lewis
acidity of the resulting species, which
enables the synthesis of previously inac-
cessible hypervalent silicon derivatives.
A convenient protocol for the selective
synthesis of functional bis(pentafluoroe-
thyl)silicon compounds is presented
(see scheme).
2
5 2
2
and O CCF3
2
Chem. Eur. J. 2016, 22, 1 – 9
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ꢀ 2016 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
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These are not the final page numbers! ÞÞ