The chemistry of [Ru(trpy)(Q)X]n+ (trpy = 2,22-terpyridine; Q = the quinolin-8-olate anion; x = cl^-, h₂o, mecn and N^-_3; n = 0 and 1)

Abstract

Reaction of [Ru(trpy)Cl₃] with quinolin-8-ol (HQ) yields [Ru(trpy)(Q)Cl]. Treatment of [Ru(trpy)(Q)Cl] with Ag⁺ in Me₂CO-H₂O (3¦1) and MeCN gives [Ru(trpy)- (Q)(H₂O)]⁺ and [Ru(trpy)(Q)(MeCN)]⁺, respectively, which were isolated as their perchlorate salts. A similar reaction in EtOH, in the presence of N_aN₃, yields [Ru(trpy)(Q)(N₃)]. All complexes are diamagnetic (low-spin, d⁶, S = 0) and show many intense m.l.c.t. transitions in the visible region. They display a reversible Ru^II-Ru^III oxidation in the -0.13-0.48 V versus s.c.e. range, followed by an irreversible Ru^III-Ru^IV oxidation in the 0.46-1.08V versus s.c.e. range and three trpy-based reductions on the negative side of s.c.e. Chemical oxidation of [Ru^II(trpy)(Q)Cl] by Ce⁴⁺ gives [Ru(trpy)-(Q)Cl]⁺ which shows intense l.m.c.t. transitions in the visible region together with a weak ligand field transition in the lower energy region. The complex is one-electron paramagnetic (low-spin, d⁵, S=½) and shows a rhombic e.s.r. spectrum in MeCN-PhMe (1¦1) solution at 77K. Chemical oxidation of [Ru(trpy)(Q)-(H₂O)]⁺ results in the formation of a µ -oxo dimer, [{Ru(trpy)(Q)}₂O]²⁺.