2007
Full Paper
Macromolecular
Chemistry and Physics
wileyonlinelibrary.com DOI: 10.1002/macp.201300764
Stereospecific Styrene Polymerization
by Methylalumoxane-Activated Ti (IV) N-
Trimethylsilylamido Complexes Bearing the
N-Biphenyl or N-(6-(2-(Diethylboryl)phenyl)-
Pyrid-2-yl) Motif
Gurram Venkata Narayana, Guangjuan Xu, Dongren Wang, Maria Speiser,
Wolfgang Frey, Michael R. Buchmeiser*
Cp’TiCl
2
( N-(6-(2-(diethylboryl)phenyl)pyrid-2-yl)SiMe
3
), [Cp’ = C
5
H
5
( 3), C
5
(CH
3
)
5
( 4)], and the
aminoborane-free half-titanocene analogs with the general formula: Cp’TiCl
2
(N-(biphenyl-
3-yl)SiMe
3
); [Cp’ = C
5
H
5
( 7), C
5
(CH
3
)
5
( 8)] are synthesized and used in the polymerization
of styrene. All the pre-catalysts are active in styrene poly-
merization, >90% syndiotactic poly(styrene) ( st-PS) is pro-
duced, exceeding that of their ansa-homologues (C
5
(CH
3
)
5
)
TiCl
2
(6-(2-(diethylboryl)phenyl)pyrid-2-ylamido)(dimethyl-
silyl) ( 9) and (C
5
(CH
3
)
5
)TiCl
2
(3-biphen-3-ylamido)(dimethyl-
silyl) ( 10) both in activity and molecular weight. Pre-catalyst
8 allows for the synthesis of high-molecular-weight st-PS
with activities up to 5000 kg
st-PS
mol
cat
-1
h
-1
. Implications of
the 2-(diethylboryl)phenyl)pyrid-2-yl group on polymerization
activity and molecular weight are discussed.
Dr. G. V. Narayana, G. Xu, Dr. D. Wang, M. Speiser,
Prof. M. R. Buchmeiser
Institut für Polymerchemie, Lehrstuhl für Makromolekulare
Stoffe und Faserchemie, Universität Stuttgart,
Pfaffenwaldring 55, D-70569 Stuttgart, Germany
E-mail: michael.buchmeiser@ipoc.uni-stuttgart.de
Dr. W. Frey
Institut für Organische Chemie, Universität Stuttgart,
Pfaffenwaldring 55, D-70569 Stuttgart, Germany
Prof. M. R. Buchmeiser
Textilchemie und Chemiefasern (ITCF),
Körschtalstr. 26, D-73770 Denkendorf, Germany
yield syndiotactic poly(styrene) ( st-PS). Zambelli et al.
[2,3]
have shown that with tetrabenzyltitanium/MAO styrene
insertion proceeds 100% via secondary insertion yielding
metal-benzyl species. Since then, significant progress
has been made.
[4–7]
st-PS is a crystalline material with a
high melting point (270 °C) and good resistance to water
and organic solvents at ambient temperature. Recent
studies have identified mono( η
5
-cyclopentadienyl) com-
plexes of group IV metals as efficient catalysts for styrene
polymerization. While [Zr( η
5
-C
5
H
5
)]-based complexes are
poorly syndioselective, the related Ti complexes are effec-
tive in the stereocontrol of poly(styrene).
[8–10]
Here, we present out results on the homopolymeri-
zation of styrene by non-bridged half-titanocene com-
plexes containing an aminoborane moiety of the formula
Cp’TiCl
2
( N(6-(2-(diethylboryl)phenyl)-pyrid-2-yl)Si(CH
3
)
3
),
Cp’ = C
5
H
5
( 3), C
5
(CH
3
)
5
( 4) and by the aminoborane-free
1. Introduction
The stereospecific polymerization of styrene was first
accomplished by Ishihara et al.
[1]
with Ti-based half-met-
allocenes in the presence of methylalumoxane (MAO) to
Macromol. Chem. Phys. 2014, 215, 2007−2013
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