Magnetostructural Properties of Some Doubly-Bridged Phenoxido Copper(II) Complexes

Three new tripod tetradentate phenolate-amines (H₂L¹, H₂L⁴ and H₂L⁹), together with seven more already related published ligands, were synthesized, and characterized. With these ligands, two new dinuclear doubly-bridged-phenoxido copper(II) complexes (3, 4), and six more complexes (1, 2, 5–8), a new trinuclear complex (9) with an alternative doubly-bridged-phenoxido and –methoxido, as well as the 1D polymer (10) were synthesized, and their molecular structures were characterized by spectroscopic methods and X-ray single crystal crystallography. The Cu(II) centers in these complexes exhibit distorted square-pyramidal arrangement in 1–4, mixed square pyramidal and square planar in 5, 6, and 9, and distorted octahedral (5+1) arrangements in 7 and 8. The temperature dependence magnetic susceptibility study over the temperature range 2–300 K revealed moderate–relatively strong antiferromagnetic coupling (AF) (|J| = 289–145 cm⁻¹) in complexes 1–6, weak-moderate AF (|J| = 59 cm⁻¹) in the trinuclear complex 9, but weak AF interactions (|J| = 3.6 & 4.6 cm⁻¹) were obtained in 7 and 8. No correlation was found between the exchange coupling J and the geometrical structural parameters of the four-membered Cu₂O₂ rings.