Synthesis and structural characterization of zinc complexes supported by amino-benzotriazole phenoxide ligands: Efficient catalysts for ring-opening polymerization of ε-caprolactone and β-butyrolactone

Two amino-benzotriazole phenol ligands, 2-(2H-benzotriazol-2-yl)-6-((diethylamino)methyl)-4-alkyl-phenol (alkyl = CH3, (BTP)-B-C1DEA-H, and alkyl = C8H17, (BTP)-B-C8DEA-H) were prepared through the Mannich condensation of 4-alkyl-2-(2H-benzotriazol-2-yl)phenol with the mixtures of excess paraformaldehyde and diethylamine under reflux conditions. Zinc complexes supported by amino-benzotriazole phenoxide ligands ((BTP-)-B-C1DEA and (BTP-)-B-C8DEA) were synthesized and fully characterized. The reaction of ZnEt2 with (BTP)-B-DEA-H (1 equiv.) produces the tetra-coordinated dimeric zinc complexes [(mu-(BTP)-B-C1DEA)ZnEt](2) (1) and [(mu-(BTP)-B-C8DEA)ZnEt](2) (2). Experimental results indicate that complex 1 catalyzes the ring-opening polymerization of epsilon-caprolactone and beta-butyrolactone with good catalytic activities in a controlled character. (C) 2011 Elsevier B.V. All rights reserved.