Abstract
The diorganoplatinum(II) complexes (bpy)Pt(Ph)2, (bpym)Pt(Ph)2, (m-bpym)(Pt(p-tol)2)2, and (m-bpym)(PtAd2)2, (bpy = 2,2'-bipyridine; bpym = 2,2'=bipyrimidine; Ph = phenyl; p-tol = p-tolyl; Ad = (1-adamantylmethyl) were subjected to two successive one-electron redns., and the one-electron redn. products were studied in situ by UV-vis-near-IR and EPR spectroscopy. The first redn. is at the heterocyclic ligand, in contrast to the metal-centered redns. in such closely similar species as Pt(bpy)(py)22+. We attribute this difference to the greater ligand field strength of carbanionic as opposed to neutral N-bound ligands. While the EPR signals of the paramagnetic species show sizable g anisotropy (1.92-2.02) in frozen soln. due to the large spin-orbit coupling const. of the metal, the rhombic g pattern, the low isotropic values (giso \textless 2), and the isotropic hyperfine coupling as obsd. and reproduced in the case of (bpym)Pt(Ph)2.bul.- all suggest a predominant localization of the unpaired electron at the a-diimine ligand. on SciFinder(R)
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