QUENCHING BY UNSATURATED FERROCENE AND FERROCENIUM DERIVATIVES OF THELUMINESCENCE OF RU(PHEN)(3)(2+)

A series of unsaturated ferrocene derivatives with the formula FcCH=CH -X (X=CHO, CN, COCH3, COOCH3, [GRAPHICS] Fc, ferrocene) have been synt hesized and oxidized to ferrocenium derivative ions. It has been found that these species can quench the (3)MLCT state of Ru(phen)(3)(2+) ef ficiently. The quenching by the ferrocene and ferrocenium derivatives occur mainly via reductive and oxidative electron transfer on the ferr ocenyl group in acetonitrile respectively. The Stern-Volmer plot is li near, from which the bimolecular quenching rate constants of the order of 10(9)-10(10) dm(3) mol(-1) s(-1) have been obtained. The rate cons tants for quenching with ferrocenium derivative ions are at or near th e diffusion-controlled limit. Linear relationships have been obtained for a plot of log k(q) vs. -Delta G of both the electron transfer and oxidative process.