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Anionic Monosubstituted Cyclopentadienylsamarium Derivatives: Catalysts for a Stereospecific Isoprene Polymerization
Author(s) -
BaudryBarbier Denise,
Andre Nicolas,
Dormond Alain,
Pardes Christine,
Richard Philippe,
Visseaux Marc,
Zhu Cheng Jian
Publication year - 1998
Publication title -
european journal of inorganic chemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.667
H-Index - 136
eISSN - 1099-0682
pISSN - 1434-1948
DOI - 10.1002/(sici)1099-0682(199811)1998:11<1721::aid-ejic1721>3.0.co;2-v
Subject(s) - chemistry , isoprene , adduct , stereospecificity , medicinal chemistry , polymerization , derivative (finance) , catalysis , ethylene , metallocene , alkyl , stereochemistry , polymer chemistry , organic chemistry , copolymer , polymer , economics , financial economics
New alkyl and allyl complexes 1 – 3 { 1 : [Cp′ 2 Sm(C 3 H 5 )] n , Cp′ = Me 3 CC 5 H 4 ; 2 : [Me 4 C 2 (C 5 H 4 ) 2 ]Sm(C 3 H 5 ) 2 Li(dme),dme = (CH 3 OCH 2 CH 2 OCH 3 ); 3 : Cp′ 2 SmMe 2 Li(dioxane)} were synthesized from (Cp′ 2 SmCl) 2 and from the magnesium derivative [Me 4 C 2 (C 5 H 4 ) 2 ]SmCl · MgCl 2 (THF) 4 ( 4 ). The ansa anionic complex 2 exhibited good activity for the stereospecific 1,4‐ trans polymerization of isoprene, whereas the neutral derivative 1 was inactive. In the same way, the anionic complex [Cp′ 2 SmMe 2 ]Li(dioxane) ( 3 ) was found to be an ethylene polymerization catalyst of very short lifetime. The lack of reactivity of 1 is related to the associated structure of this coordinatively unsaturated complex: this fact was established by the formation of the carbene adduct Cp′ 2 Sm(C 3 H 5 )[C(N i Pr) 2 (CMe) 2 ] ( 1′ ). Crystals of 1′ were isolated but this new compound undergoes a partial rearrangement into a tris‐Cp′ species in solution. Similar behaviour is observed for the analogous complex Cp′ 2 SmCl[C(N i Pr) 2 (CMe) 2 ] ( 1′′ ). The X‐ray crystal structure revealed the formation of the adduct, as a toluene solvate, which exists in benzene solution in equilibrium with Cp′ 3 Sm and Cp′SmCl 2 [C(N i Pr) 2 (CMe) 2 ] 2 . The catalytic behaviour of 2 is compared with that of other early lanthanide derivatives.