ELECTROCHEMISTRY, ELECTRON-SPIN-RESONANCE, OPTICAL SPECTROSCOPY, AND REACTIVITY OF ORGANOMETALLIC PLATINUM(II) COMPLEXES CONTAINING STRONGLY PI-ACCEPTING AROMATIC ALPHA DIIMINE LIGANDS

Low-lying metal-to-ligand charge transfer (MLCT) transitions of the new complexes LPtPh2 (L= 3,3'-bipyridazine (bpdz), 4,4'-bipyrimidine (bpm), 2,2'-bipyrazine (bpz) and 1,4,7,10-tetraazaphenanthrene (tap)) have been studied by emission and solvent-dependent absorption spectroscopy. The complex (bpm) PtPh2 is strongly solvatochromic, and exhibits five absorption bands in toluene solution, but does not show luminescence. The other complexes emit visible light on excitation in the solid or in acetonitrile solution (bpdz complex). The one- and two-electron-reduced states were generated electrochemically; the ESR spectra of the paramagnetic intermediates, including [(bpy)PtPh2]-., are consistent with the formulation Pt(II)/(L-.). The rate of oxidative addition of iodomethane to Ph2Pt(L) correlates with the basicity of L.