Photoredox Reactions of Hg(CN)2/[Fe(CN)6]4 and [HgCo2(CN)10]6 Induced by Inner-Sphere Metal to Metal Charge Transfer Excitation

In com plexes o f the type [(NC )2H gIIN C FeII(CN )5]4~ which are formed in aqueous mixtures of H g(C N )2 and [Fe(C N )6]4~ both metals are weakly coupled. Optical metal to metal charge transfer (M M CT) excitation from F e11 to Hg" leads to the reduction of Hg" to Hg" an the oxidation of [Fe(C N )6]4~ to [Fe(C N )6]3~. In the complex [(NC)5CoIH g IIC o I(CN )5]6" the metals are strongly coupled by direct but polar metal metal bonds. MMCT (C o '^ H g 11) excitation induces the photo­ redox reaction: [H gCo2(C N )l0]6_—>Hg° + 2[C o(C N )5]3~.