Synthesis, characterization and catalytic studies of aluminium complexes containing sulfonamido–oxazolinate or –pyrazolinate ligands

Abstract A series of sulfonamido–oxazolinate ligand precursors, HNSO 2 Ph H Oxa , HNSO 2 Ph Me Oxa , HNSO 2 Ph TriMe Oxa , or sulfonamido–pyrazolinate ligand precursors, HNSO 2 Ph H Pz H , HNSO 2 Ph Me Pz H , HNSO 2 Ph TriMe Pz H , HNSO 2 Ph F Pz H , HNSO 2 Ph H Pz Me , HNSO 2 Ph Me Pz Me , HNSO 2 Ph TriMe Pz Me , have been prepared. Treatment of ligand precursors, HNSO 2 Ph A Oxa or HNSO 2 Ph A Pz B , with 1.1 equiv. of AlMe 3 in THF affords aluminium sulfonamido–oxazolinate dimethyl complexes, (NSO 2 Ph A Oxa)AlMe 2 [A = H ( 1 ); A = Me ( 2 ); A = TriMe, ( 3 )], or aluminium sulfonamido–pyrazolinate dimethyl complexes, (NSO 2 Ph A Pz B )AlMe 2 [A = H, B = H ( 4 ); A = Me, B = H ( 5 ); A = TriMe, B = H ( 6 ); A = F, B = H ( 7 ); A = H, B = Me ( 8 ); A = Me, B = Me ( 9 ); A = TriMe, B = Me ( 10 )]. The aluminium bis(sulfonamido–pyrazolinate) methyl complex 5 ′ was isolated from recrystallization of 5 as minor product. The molecular structures of compounds 2 , 5 ′ and 8 were determined by single-crystal X-ray diffraction techniques. Their catalytic activities towards the ring opening polymerization of e-caprolactone in the presence of benzyl alcohol are also under investigation.