Synthesis and characterization of copper(II) and nickel(II) complexes of a di- N-carboxymethylated tetraaza macrocycle

Abstract

The reaction of 3,14-dimethyl-2,6,13,17-tetraazatricyclo[14,4,0 1.18,0 7.12]docosane (L 1) with bromoacetic acid produced the macrocycle (L 2=2,13-bis(2-carboxymethyl)-3,14-dimethyl-2,6,13,17-tetraazatricyclo[14,4,0 1.18,0 7.12]docosane) in which two carboxymethyl groups are appended. The complexes [NiL 2]·4H 2O ( 2) and [CuL 2]·4H 2O ( 3) have been prepared and characterized. The two pendant carboxymethyl groups of the macrocyclic ligand are trans to each other, and the absolute configuration is a trans-III in the solid state. The crystal structures of 2 and 3 revealed an axially elongated octahedral geometry with four nitrogen atoms of the macrocycle and two oxygen atoms of the pendant arms at the axial positions. The nickel(II) and copper(II) ions are located at an inversion center. Macrocycle L 2 reacts more rapidly with metal (II) ions than does L 1. Spectra and electrochemical behaviors of the complexes are also discussed.