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Novel Neutral and Cationic Aluminium Alkyl Complexes Supported by Potentially Tridentate O,N,L‐Type Aminophenolate Ligands and Their Use in Propylene Oxide Polymerization
Author(s) -
Issenhuth JeanThomas,
Pluvinage Julien,
Welter Richard,
BelleminLaponnaz Stéphane,
Dagorne Samuel
Publication year - 2009
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/ejic.200900703
Subject(s) - chemistry , cationic polymerization , medicinal chemistry , stereochemistry , yield (engineering) , chelation , polymer chemistry , inorganic chemistry , materials science , metallurgy
Potentially tridentate O,N,L‐type aminophenol proligands of the type 2‐{CH 2 N(C 4 H 8 L)}‐6‐R‐C 6 H 3 OH ( 1a : R = Ph, L = O; 1b : R = Ph, L = NMe; 1c : R = t Bu, L = O; 1d : R = t Bu, L′ = NMe) and 6‐{CH 2 L}‐2‐CPh 3 ‐4‐Me‐C 6 H 2 OH ( 1e : R = CPh 3 , L = O; 1f : R = CPh 3 , L′ = NMe) readily react with AlMe 3 through an alkane elimination reaction to afford the corresponding aminophenolate aluminium dimethyl complexes η 2 ‐ N , O ‐[2‐{CH 2 N(C 4 H 8 L)}‐6‐R‐C 6 H 3 O]AlMe 2 ( 2a : R = Ph, L = O; 2b : R = Ph, L = NMe; 2c : R = t Bu, L = O; 2d : R = t Bu, L′ = NMe) and η 2 ‐ N , O ‐[6‐{CH 2 (C 4 H 8 L)}‐2‐CPh 3 ‐4‐Me‐C 6 H 2 O]AlMe 2 ( 2e : R = CPh 3 , L = O; 2f : R = CPh 3 , L′ = NMe), respectively, as determined by X‐ray crystallography in the case of compounds 2b – e . These neutral Al dimethyl complexes all feature a (η 2 ‐ O , N )Al chelate, whether in solution or in the solid state, and complexes 2a , 2b , 2d and 2f may be readily ionized by B(C 6 F 5 ) 3 to yield Al cations of the type (η 3 ‐ O , N, L )AlMe + ( 3a , 3b + , 3d + and 3f + ) as dissociated MeB(C 6 F 5 ) 3 – salts in solution. The stability of these Al cations appears to be greatly dependent on the steric crowding around the Al centre. Despite ring strain associated with the coordination of the extra L ligand, the solution behaviour of such Al cations are consistent with the effective coordination of the extra L ligand to the Al metal centre under the studied conditions. Some of these cations were found to be highly active in propylene oxide (PO) polymerization under mild conditions to yield atactic PPO with a moderate polydispersity. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2009)