A radical-bridged bis(ferrocenylcopper(I)) complex: Structural identity, multifrequency EPR, and spectroelectrochemistry

摘要

The paramagnetic blue complex {(mu-adcO(t)Bu)[ Cu(dppf)](2)}(PF6) contains two heterodinuclear 1,1 '-bis(diphenylphosphinoferrocene) copper(I) moieties, bridged by the radical anion of di-tert-butylazodicarboxylic ester (adcO(t)Bu). The assignment of oxidation states is supported by crystal structure determination and by variable frequency EPR spectroscopy which provides hyperfine (9.5GHz) and g anisotropy information (285GHz). Cyclic voltammetry and UV/ Vis/ NIR spectroelectrochemistry indicate reversible one-electron oxidation of the adcO(t)Bu(.)-bridge prior to the quasi-reversible two-electron oxidation of the well separated (12.55 angstrom) ferrocene termini. One-electron reduction to the adcO(t)Bu(2)-bridged system occurs with concomitant loss of the long-wavelength metal-to-ligand charge transfer absorption. (C) 2007 Elsevier B. V. All rights reserved.