Synthesis, characterization and electrochemical studies of oximato-bridged binuclear osmium(II)-oxovanadium(IV) complexes

Abstract

The reaction of <i>facial-</i>[<i>OsA₃</i>]<i>^-</i> (<b>3</b> [A = anion of arylazo oxime (HA, <b>1</b>)] with VO(acac)₂ furnishes hetero-bimetallic complexes of the type [OsA₃VO(acac)] (<b>4</b>). Replacement of acac by neutral N,N donors (B) like 2,2' -bipyridine and 1, 10-phenanthroline gives cationic species of the type [OsA₃VO(B)]⁺ isolated as perchlorate salt <b>5</b>. Extrusion of <b>4</b> and <b>5</b> with NaOH reverts to mononuclear <b>3.</b> All the complexes have been characterized using their spectroscopic, magnetic and physicochemical results. A1: 1 correspondence in the IR spectra of 4 (A = A²) and corresponding well-characterized iron-vanadium analogue, [FeA²₃ VO(acac)] suggests cognate structure <b>6</b>. The new binuclear complexes are one-electron paramagnets and VO^{2 +} core is EPR-active. The <i>g</i>-values suggest the occupancy of the unpaired electron in <i>d_xy </i>orbital. The complexes show a number of charge-transfer transitions in 200-700 nm region and exhibit nearly reversible osmiurm(III)-osmium(II) couple.