Copper(II) and zinc(II) complexes of N,N-bis(benzimidazole-2-ylmethyl)-amine. Synthesis, formation constants and the crystal structure of [ZnLCl]₂]. MeOH. Catalytic activity of the complexes in the hydrolysis of the phosphotriester 2,4-dinitrophenyl diethyl phosphate

The copper(II) and zinc(II) complexes of N,N-bis(benzimidazole-2-ylmethyl)amine (L) have been prepared and the crystal structure of [ZnLCl₂]. MeOH determined. The complex is five-coordinate with a distorted square pyramidal geometry on zinc. Two pyridine nitrogen donors from the imidazole groups, the secondary amino group and one chloride act as in-plane donors with the axial site occupied by chloride. The zinc(II) lies some 0.65 Å above the basal plane. The stepwise protonation constants of the ligand have been obtained, log K₁₁=5.638(3) and log K₁₂=10.12(1) and the stability constants (log β_1mh) for the copper(II) and zinc(II) complexes determined using 50% MeOH-H₂O as solvent. The hydroxoaqua complexes [ML(OH) (OH₂)]⁺ show only slight catalytic activity in the hydrolysis of the phosphotriester 2,4-dinitrophenyl diethyl phosphate.