Investigation of the electron transfer properties between metal centers in binuclear and trinuclear cyanido-bridged mixed valence complexes with cis/trans-configuration

Abstract

To investigate the electron transfer properties between metal centers and their influencing factors in binuclear and trinuclear cyanido-bridged mixed valence complexes with cis/trans-configuration, binuclear cis-[Cp(dppe)Fe(μ-NC)Ru(5,5′-dmbpy)₂(μ-CN)][PF₆]_n (cis-1[PF₆]_n, n = 1, 2) and trinuclear cis/trans-[Cp(dppe)Fe(μ-NC)Ru(5,5′-dmbpy)₂(μ-CN)Fe(dppe)Cp][PF₆]_n (cis/trans-2[PF₆]_n, n = 2, 3, 4) (Cp = 1,3-cyclopentadiene, dppe = 1,2-bis(diphenylphosphino)ethane, 5,5′-dmbpy = 5,5′-dimethyl-2,2′-bipyridyl) cyanido-bridged complexes were synthesized and well characterized. The experimental results indicate that the presence of the other terminal fragment Cp(dppe)Fe^III in cis-2[PF₆]₄ results in higher MMCT energy than that of cis-1[PF₆]₂. In addition, the trans-configuration is more conducive to electron transfer between metal centers than the cis-configuration in trinuclear cyanido-bridged mixed valence complexes. Moreover, these mixed valence complexes cis-1[PF₆]₂ and cis/trans-2[PF₆]_n (n = 3, 4) could be assigned to Class II systems according to Robin and Day.