730
BELYAKOVA et al.
the addition of the vinyltriethoxysilane. This difference
in the behavior of allyl trifluoroacetate and allyl
perfluorobutyrate from allyl acetate is explained
apparently by the difference in the ability of these
reagents to the reaction of displacement of the vinyl
ligand in the platinum-olefin complex. Trifluoroacetate
addition to the Speier catalyst at the hydrosilylation of
allyl acetate only reduces the reaction rate but does not
exclude reduction.
Ni(1,5-cod)2 (VII), Ni (1,5-cod)·(DQ)1 (VIII), Ni(DQ)2
(IX), Ni(C10H12)2·(DQ) (X), Ni(TCC)2 (XI); hydride
3
complexes: HNi(PPh3)2Br (XII), HNi[P(C6H11)3]2Br
(XIII); alkyl complex EtNi[P(C6H11)3](acac) (XIV), as
well as some of these complexes and NiCl2 (XV), Ni
(acac)2 (XVI) mixed with the additives PPh3 (XVII),
CuCl (XVIII), and phosphine oxides Oct3P=O (XIX),
MePh2P=O (XX), Bu2PhP=O (XXI), ClC6H4P(=O)Et2
(XXII),
HOC6H4P(=O)Et2
(XXIII),
forming
complexes in situ (molar ratio complex : additive =
The rate of a reaction depends on the applied
catalyst. It may be that the reduction reaction proceeds
through the formation π-allyl complex of platinum
whose formation is favored by the existence of ligand-
acceptors [4].We quantitatively characterized the
increased role of reduction reaction depending on X by
the molar ratio of product of addition and reduction
ADD/RED. The following sequence was found:
PhO < MeCOO < CH2=C(Me)COO < CF3COO <
C3F7COO < Cl.
1:2).
Content of the adduct in the mixture formed after
the reaction of hydrosilylation of allyl phenyl ether
with triethoxysilane in the presence of the studied
catalysts did not exceed 14.4% (IX + XIX), and in
some cases along with the main product PhO(CH2)3SiX3
(XXIV) formed hydrogenated compound PhO·
(CH2)3SiHX2 (XXV), as is characteristic of nickel
catalysts.
PhOCH2CH=CH2 + HSiY3
→ PhO(CH2)3SiY3 + PhO (CH2)3SiHY2.
(6)
This series coincides with the series of increase in
the acidity of the residue X. Perhaps the suppression of
formation of π-allylic complexes is due to the positive
effects of amines [5] and amides [6] on the yield of the
addition product at the hydrosilylation of allyl chloride
in the presence of platinum catalysts. On the contrary,
yield of γ-chloropropyltrichlorosilane at the hydro-
silylation of allyl chloride with trichlorosilane using as
a catalyst a solution of H2PtCl6 in allyl chloride is
reduced by 15% compared to the Speier catalyst,
probably due to the partial formation of π-allyl
complexes. In the hydrosilylation of allyl chloride with
triethoxysilane the ratio ADD/RED is particularly low
(0.18). At the use of hydrochlorosilane instead of
triethoxysilane the ADD/RED increases, and in the
presence of the Speier catalyst with vinyltriethoxy-
silane it reaches 13.46. It should be noted that in the
hydrosilylation of allyl acetate with triethoxysilane
even in the presence of the Speier catalyst with
vinyltriethoxysilane it was impossible to eliminate
completely the reduction, but only possible to increase
the ADD/RED ratio.
XXIV
XXV
Similar data on the hydrosilylation of hexene with
methyldichlorosilane were obtained by V.O. Reikhsfel’d
and N.K. Skvortsov [8].
The content of the product of reduction C6H5OSiY3
(XXVI) reached maximum 60% (Y = OEt) and 13.8%
(Y = Cl), but the second product, namely propylene
[Eq. (2)], and the products of hydrosilylation of the
latter were not found. Perhaps, propylene underwent
polymerization: in the synthesis always a dark-colored
solid precipitate is formed, in some experiments in the
GLC was detected a peak between the peaks of
phenyltriethoxysilane and γ-phenoxypropyltriethoxy-
silane similar to that of propylene tetramer, that
disappears at longer synthesis. The following sequence
of activity in the reaction of reduction [Eq. (2)] is
obtained (in parentheses the content of the reduction
product in the reaction mixture, %): XVI + XXIII
(60.6) > XVI + XXI (56.4) > X + XIX (55.3) > X +
XVII (46.6) > XVI + XXII (46.2) > XVI + XIX
(40.7) > XI + XIX (39.8) > IX + XIX (35.8) > XV +
XIX (29.0)
Nickel is known to form π-allyl complexes easier
than platinum [7]. As catalysts for hydrosilylation of
allyl phenyl ether with hydrosilanes we examined the
following bivalent nickel complexes: NiCl2·(PPh3)2 (I),
NiCl2·[P(C6H11)3]2 (II), NiBr2·(PBu3)2 (III), NiBr2·
(PPh3)2 (IV); zero-valence nickel complexes: Ni(CO)2·
(PPh3)2 (V), Ni(C6H5CH=CHC6H5)·(PPh3)2 (VI),
The strongest reductive properties display nickel
complexes containing as ligands duroquinone (VIII–
X) and tetracyclone (XI) with phosphine oxides.
1
DQ = duroquinone.
2
C10H12 is biscyclopentadiene.
3
TCC is tetracyclone.
RUSSIAN JOURNAL OF GENERAL CHEMISTRY Vol. 80 No. 4 2010