PHOTOREDOX REACTIONS OF TRIS(2,2'-BIPYRAZINE)RUTHENIUM(II), TRIS(2,2'-BIPYRIMIDINE)RUTHENIUM(II) AND TRIS(2,3-BIS[2-PYRIDYL]PYRAZINE)RUTHENIUM(II) CATIONS WITH PHENOLATE IONS IN AQUEOUS ACETONITRILE

The photoinduced electron transfer (PET) reactions of six Ru(II) compl exes with several phenolate ions have been measured in 50% aqueous ace tonitrile (v/v) and the observed quenching constant (k(q)) values are sensitive to the nature of the ligand and the structure of the phenola te ion. A steric effect seems to play an important role in this PET re action. The temperature dependence study of the quenching of [Ru(bpy) (3)](2+) with ArO- reveals that the unfavourable entropy values associ ated with bulky quenchers are responsible for the observed steric effe ct. The change of k(q) values with Delta G degrees is in accordance wi th the semiclassical theory of electron transfer.