Electrochemical and spectroelectrochemical studies on platinum complexes containing 2,2′-bipyridine

Abstract

The electrochemical and spectroelectrochemical (UV/VIS/NIR and EPR) properties of a series of complexes of general formula [Pt(bipy)L₂]ⁿ⁺(L = Cl^– or CN^–, n= 0; L = NH₃, py, PMe₃ or L₂= en, n= 2; bipy = 2,2′-bipyridine, py = pyridine, en = ethylenediamine) have been investigated. The complexes undergo a reversible one-electron reduction process at potentials of ca.–1 V vs. Ag–AgCl. In each case UV/VIS/NIR spectra of the one-electron reduction products were consistent with co-ordinated bipyridyl anion-radical species rather than d⁹ metal centres. Electron paramagnetic resonance spectra of the chemically or electrochemically generated 17-electron species, in conjunction with the results of extended-Hückel molecular-orbital calculations, show a significant admixture of metal 5d_yz and/or 6p_z orbitals in the singly-occupied molecular orbital. The complex [Pt(bipy)(PMe₃)₂][BF₄]₂ has been prepared.