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

Abstract The copper(II) and zinc(II) complexes of N,N-bis(benzimidazole-2-ylmethyl)amine (L) have been prepared and the crystal structure of [ZnLCl 2 ]. 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 A above the basal plane. The stepwise protonation constants of the ligand have been obtained, log K 11 =5.638(3) and log K 12 =10.12(1) and the stability constants (log β 1mh ) for the copper(II) and zinc(II) complexes determined using 50% MeOH–H 2 O as solvent. The hydroxoaqua complexes [ML(OH) (OH 2 )] + show only slight catalytic activity in the hydrolysis of the phosphotriester 2,4-dinitrophenyl diethyl phosphate.