A novel copper(II) complex of a tripodal ligand with phenolate-phenol interligand, intramolecular hydrogen bonding

Abstract

A novel tripodal ligand with three different arms, viz., pyridine, phenol and an oxime and its copper(II) complex were synthesised. The X-ray crystal structure of the compound reveals that it is a dinuclear complex consisting of two copper(II) ions doubly bridged by two oximato groups in a trans arrangement. The complex contains unusual cis-axially coordinated phenolates as well as a novel interligand, intramolecular phenolate-phenol hydrogen bond. Variable-temperature magnetic susceptibility measurements revealed that the two copper(II) centers are strongly antiferromagnetically coupled, with the exchange coupling constant -2J = 800(42) cm(-1) (H = -2J S(1) x S(2)) for the two interacting S = 1/2 centres. The complex yields an (1)H NMR spectrum in CD(3)CN solution at room temperature, with relatively sharp signals and rather small hyperfine shifts, evidencing that the antiferromagnetically coupled dinuclear core is maintained in solution.