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Lanthanide borohydrido complexes for MMA polymerization: syndio‐ vs iso‐ stereocontrol
Author(s) -
BarbierBaudry Denise,
Bouyer Frédéric,
Madureira Bruno Ana Sofia,
Visseaux Marc
Publication year - 2006
Publication title -
applied organometallic chemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.53
H-Index - 71
eISSN - 1099-0739
pISSN - 0268-2605
DOI - 10.1002/aoc.1002
Subject(s) - lanthanide , tacticity , chemistry , polymerization , cyclopentadienyl complex , ligand (biochemistry) , catalysis , divalent , polymer chemistry , medicinal chemistry , derivative (finance) , polymer , monomer , stereochemistry , organic chemistry , ion , biochemistry , receptor , financial economics , economics
Abstract This paper presents an extensive study of the polymerization of MMA with borohydrido lanthanide complexes for the first time. Catalytic systems are made from a lanthanide derivative bearing zero one, or two bulky ligands: substituted cyclopentadienyl (Cp *′ = C 5 Me 4 n Pr, Cp 4i = C 5 H i Pr 4 , Cp Ph3 = H 2 C 5 Ph 3 ‐1,2,4), and/or diketiminate ([( p ‐tol)NN] = [( p ‐CH 3 C 6 H 4 )N(CH 3 )C] 2 CH), in the presence of variable quantities of alkylating agent. With BuLi in apolar medium, highly isotactic polymer (up to 95.6%) is formed. In THF, syndiotactic‐rich PMMA is obtained whatever the nature of the co‐catalyst (BuLi or Mg n Bu 2 ). The presence of an electron‐withdrawing ligand such as Cp Ph3 allows high syndioregularity, up to 81.8% at 0 °C, together with the highest conversion. There is quite good concordance between calculated and experimental molecular data in THF. Divalent Cp *′ 2 Sm II (THF) and (Cp Ph3 ) 2 Sm II (THF) are active as single‐component initiators; the former affords PMMA 88% syndiotactic at 0 °C. Copyright © 2005 John Wiley & Sons, Ltd.