Heterometallic Complexes Based on Triphenylantimony(V) Quinone-Catecholate

Heterometallic chromium(III) CrIII[(SQ-Cat)SbPh3]3 (I), copper(II) CuII[(SQ-Cat)SbPh3]2 (II), and zinc I2Zn(Q-Cat)SbPh3 (III) and IZn(SQ-Cat)SbPh3 (IV) complexes, where SQ is the corresponding o-semiquinone radical anion, and Cat is the catecholate dianion (mono- and direduced forms of the quinone fragment), are synthesized on the basis of the mononuclear triphenylantimony(V) quinone-catecholate complex (Q-Cat)SbPh3, which was derived from 4,4'-di-(6-tert-butyl-3-methylbenzo-1,2-quinone) (Q-Q). The one-electron oxidation and one-electron reduction of chromium complex I afford the paramagnetic derivatives [CrIII[(Q-Cat)SbPh3][(SQ-Cat)SbPh3]2]+ (I+) and [CrIII[(Cat-Cat)SbPh3][(SQ-Cat)SbPh3]2]– (I–), respectively, which are easily detected by EPR spectroscopy. The EPR spectroscopy data and measurements of the temperature dependence of the magnetic susceptibility of copper complex II indicate in favor of the localization of the lone electron on the organic ligand, which can be explained by the antiferromagnetic metal–ligand exchange in this complex (J(SQ-Cu) = –157 cm–1, J(SQ-SQ) = –10.0 cm–1). The coordination of (Q-Cat)SbPh3 as neutral o-quinone to zinc iodide with the formation of complex III increases significantly the oxidation ability of the quinone fragment in this complex (ERed1 = 0.43 V for III and –0.45 V for (Q-Cat)SbPh3 vs. Ag/AgCl/KCl(sat.)), and the complex can oxidize the iodide anion to iodine with the formation of paramagnetic derivative IV, whose EPR spectrum is characteristic of complexes of the M(SQ-Cat) type. The redox properties of complexes I and III are studied by cyclic voltammetry.