ELECTROCHEMICAL-BEHAVIOR OF [RU(II)(L)(CO)2CL2], [RU(II)(L)(CO)CL3][ME4N] AND [RU(II)(L)(CO)2(CH3CN)2][CF3SO3]2 COMPLEXES (L=2,2'-BIPYRIDINE OR 4,4'-ISOPROPOXYCARBONYL-2,2'-BIPYRIDINE)

The electrochemical behaviour of the complexes [Ru(II)(L)(CO)2Cl2], [Ru(II)(L)(CO)Cl3][Me4N] and [Ru(II)(L)(CO)2(CH3CN)2][CF3SO3]2 (L = 2,2'-bipyridine or 4,4'-isopropoxycarbonyl-2,2'-bipyridine) has been investigated in CH3CN. The oxidation of [Ru(L)(CO)2Cl2] produces new complexes [Ru(III)(L)(CO)(CH3CN)2Cl]2- as a consequence of the instability of the electrogenerated transient Ru(III) species [Ru(III)(L)(CO)2Cl2]+. In contrast, the oxidation of [Ru(II)(L)(CO)Cl3][Me4N] produces the stable [Ru(III)(L)(CO)Cl3] complex. In contrast [Ru(II)(L)(CO)2(CH3CN)2][CF3SO3]2 is not oxidized in the range up to the most positive potentials achievable. The reduction of [Ru(II)(L)(CO)2Cl2] and [Ru(II)(L)(CO)2(CH3CN)2][CF3SO3]2 results in the formation of identical dark blue strongly adherent electroactive films. These films exhibit the characteristics of a metal-metal bond dimer structure. No films are obtained on reduction of [Ru(II)(L)(CO)Cl3][Me4N]. The effect of the substitution of the bipyridine ligand by electron-withdrawing carboxy ester groups on the electrochemical behaviour of all these complexes has also been investigated.