Synthesis and catalytic application of aluminium anilido-pyrazolate complexes

Abstract

A series of aluminium complexes containing anilido-pyrazolate ligands is described. Reactions of four anilido-pyrazolate ligand precursors, HNPhPz, HNPh(TriMe)Pz, HNPh(OMe)Pz, or HNPh(SMe)Pz [HNPhPz = ortho-C(6)H(4)(NH-phenyl)(1-pyrazole); HNPh(TriMe)Pz = ortho-C(6)H(4)(NH-2,4,6-trimethylphenyl)(1-pyrazole); HNPh(OMe)Pz = ortho-C(6)H(4)(NH-2-methoxyphenyl)(1-pyrazole); HNPh(SMe)Pz = ortho-C(6)H(4)(NH-2-methylthiophenyl)(1-pyrazole)], with one molar equivalent of AlMe(3) in toluene give the aluminium dimethyl complexes, (NArPz)AlMe(2) [Ar = phenyl, (NPhPz)AlMe(2) (1); Ar = 2,4,6-trimethylphenyl, (NPh(TriMe)Pz)AlMe(2) (2); Ar = 2-methoxyphenyl, (NPh(OMe)Pz)AlMe(2) (3); Ar = 2-methylthiophenyl, (NPh(SMe)Pz)AlMe(2) (4)], respectively. The molecular structures are reported for compounds 1 and 3. Their catalytic activities toward the ring opening polymerisation reaction of e-caprolactone in the presence of BnOH are also under investigation.