Synthesis and Characterization of New Polyaza Non-macrocyclic and Macrocyclic Nickel(II) Complexes Containing One 1,3-Diazacyclohexane Ring

Abstract

A new nickel(II) complex ( = 1-(2-aminoethyl)-3-(N-{2-aminoethyl}aminomethyl-1,3-diazacyclohexane) containing one 1,3-diazacyclohexane ring has been prepared selectively by the metal-template condensation of formaldehyde with N-(2-aminoethyl)-1,3-propanediamine and ethylenediamine at room temperature. The complex reacts with nitroethane and formaldehyde to yield the pentaaza macrocyclic complex ( = 8-methyl-8-nitro-1,3,6,10,13-pentaazabicyclo[13.3.1]heptadecane) bearing one C- pendant arm. The reduction of by using Zn/HCl produces ( = 8-amino-8-methyl-1,3,6,10,13-pentaazabicyclo[13.3.1]heptadecane) bearing one coordinated C- pendant arm that is readily protonated in acid solutions. The hexaaza macrocyclic complex ( = 8-phenylmethyl-8-nitro-1,3,6,8,10,13-hexaazabicyclo[13.3.1]heptadecane) bearing one N- pendant arm has also been prepared by the reaction of with benzylamine and formaldehyde. The nickel(II) complexes of , , and have square-planar coordination geometry in the solid states and in nitromethane. However, they exist as equilibrium mixtures of the square-planar (L = , , or ) and octahedral species in various coordinating solvents (S); the proportion of the octahedral species is strongly influenced by the ligand structure and the nature of the solvent. Synthesis, spectra, and chemical properties of the nickel(II) complexes of are described.