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, ^C1DEABTP-H, and alkyl = C₈H₁₇, ^C8DEABTP-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 (^C1DEABTP ^- and ^C8DEABTP^-) were synthesized and fully characterized. The reaction of ZnEt₂ with ^DEABTP-H (1 equiv.) produces the tetra-coordinated dimeric zinc complexes [(μ- ^C1DEABTP)ZnEt]₂ (1) and [(μ-^C8DEABTP)ZnEt] ₂ (2). Experimental results indicate that complex 1 catalyzes the ring-opening polymerization of ε-caprolactone and β-butyrolactone with good catalytic activities in a controlled character.