Structural and magnetic properties of O-bridged tetranuclear and binuclear Cu(II) complexes

Abstract

Two copper(II) complexes [Cu 4(L 1) 4] ( 1) and [Cu 2(phen) 2(HL 2) 2] (ClO 4) 2 ( 2) have been synthesized from two potentially tridentate ligands N-(2-hydroxybenzyl) propanolamine (H 2L 1) and N-(2-hydroxybenzyl) ethanolamine (H 2L 2). X-ray analyses revealed that 1 contains a Cu 4O 4 cubane core, with each two Cu(II) atoms bridged by a pair of alkoxides; 2 has a bis(μ 2-phenoxo)-bridged dicopper(II) structure. Variable temperature magnetic measurements of 1 have revealed that the correlation between 2 J and the bridge angles φ for 1 shows a very strong antiferromagnetic tendency, i.e. the ferromagnetic and antiferromagnetic interactions cross at the φ of 94.5°. The relatively weak antiferromagnetic interactions (2 J=−226.8 cm −1) with respect to the bridge angles ( φ=100.4°) for 2 have been ascribed to the pyramidal distortions at the phenoxide oxygen atoms in addition to the unfavorable overlaps of the magnetic orbitals for the highly distorted copper coordination polyhedra.