Zusammenfassung
A comprehensive ESR study of 11 mononuclear and 5 dinuclear singly reduced tris(a-diimine)ruthenium (II) complexes of the general formulas [(L)3Ru]+.bul., [(L)(bpy)2Ru]+.bul., and [(bpy)2Ru(m-L)Ru(bpy)2]3+.bul.; 2,2'-bipyridine; L, other a-diimine) shows a variety of g factors and spectral resoln. All paramagnetic species are true anion-radical complexes with little g anisotropy and relatively small but characteristically pos. differences g(ligand radical) - g(complex). The variations correlate with the calcd. properties. of the ligands and with spectroscopic and electrochem. data for the diamagnetic precursor complexes. In particular, the g shifts depend (1) on the extent of metal-ligand interaction and (2) on the energy differences between the singly occupied and neighboring unoccupied or completely filled orbitals. Virtually complete localization of the unpaired electron on the better P-accepting ligang L has been established for the mono- and dinuclear heteroleptic systems, while fast spin exchange on the ESR time scale is evident from the ESR line width of all singly reduced homoleptic complexes. [on SciFinder(R)]
Nutzer
