SYNTHESIS, SPECTROELECTROCHEMICAL CHARACTERIZATION AND SOLVATOCHROMICSTUDIES OF ARYLAZOIMIDAZOLEPALLADIUM(II) CATECHOLATES

The ternary complexes, [Pd(RaaiCH(2)Ph)(OO)] (4-6), where RaaiCH(2)Ph = N(1)-benzyl-2-(arylazo)imidazole [p-RC6H4N = NC3H2N2CH2Ph (2), R = H (4), Me (5) and Cl (6)] and (OO) = catechol [catH(2), (a)], 4-t-butyl catechol [tbcatH(2), (b)], 3,5-di-t-butylcatechol [dtbcatH(2), (c)] an d tetrachlorocatechol [tccatH(2), (d)], have been prepared and charact erized by elemental analyses, i.r., u.v.-vis. and H-1-n.m.r. data. Cyc lic voltammograms suggest four successive redox responses that are hig hly sensitive to the nature of the substituents. The complexes exhibit a ligand-to-ligand charge transfer (LLCT) band and a negative solvato chromic effect. The position of the band is largely dependent on the s ubstituent type on the catechol frame and is qualitatively assigned as the 3b(1)l(cat) --> pi (aai) transition.