ESR, solid-state P-31 MAS NMR, and UV-vis-NIR studies on linear Cu-I Cu-II Cu-I trinuclear species: Crystal structure of bis-mu-salicylato (2(-))-1:2 kappa O-4; 2:3 kappa O-4-tetrakis (triphenylphosphine-1 kappa P-2, 3 kappa P-2)-tricopper(I, II, I), (PPh

Abstract

A novel neutral mixed-valence Cu(I)Cu(II)Cu(I) linear trinuclear copper metallomacrocycle [(PPh3)(2)Cu](2) [mu-o-OC6H4COO](2)Cu (3) has been synthesized and characterized. Compound 3 consists of two Cu(l) ions and one Cu(II) ion which are bridged by two salicylate (2(-)) ligands, and the external copper(l) atoms are coordinated by four terminal triphenylphosphines. The essentially localized mixed-valence [Cu(I)Cu(II)Cu(I)] formulation for 3 was determined on the basis of X-ray crystallography, solid-state P-31 MAS NMR, and ESR spectroscopy. The solid-state P-31 MAS NMR spectra of 3 is reported, affording delta[P(2)] = -1.7 ppm with (1)(J)[Cu(I), P] = 1330 Hz and delta[P(1)] = -3.4 ppm with (1)(J)[Cu(I), P] = 1600 Hz. UV-vis-NIR spectral measurement demonstrates the Robin-Day class II behavior of the mixed-valence compound 3 with a weak copper-copper interaction. Crown Copyright (C) 2009 Published by Elsevier B.V. All rights reserved.