Effects of cis/trans-Configuration and Ligand Substitution of the Cyanidometal Bridge on Metal to Metal Charge Transfer Properties in Mixed Valence Complexes

To investigate the effects of cis/trans-configuration of the cyanidometal bridge and the electron donating ability of the auxiliary ligand on the cyanidometal bridge on metal to metal charge transfer (MMCT) in cyanidometal-bridged mixed valence compounds, two groups of trinuclear cyanidometal-bridged compounds cis/trans-[Cp(dppe)Fe(mu-NC)Ru(4,4'-dmbpy)(2)(mu-CN)Fe(dppe)Cp][PF6](n) (n=2 (cis/trans-1[PF6](2)), 3 (cis/trans-1[PF6](3)), 4 (cis/trans-1[PF6](4))) and cis/trans-[Cp(dppe)Fe(mu-NC)Ru(bpy)(2)(mu-CN)Fe(dppe)Cp][PF6](3) (cis/trans-2[PF6](3)) were synthesized and fully characterized. The experimental results indicate that for these one- and two-electron oxidation mixed valence compounds, the trans-configuration compounds are more beneficial for MMCT than the cis-configuration compounds, and increasing the electron donating ability of the auxiliary ligand on the cyanidometal bridge is also conductive to MMCT. Moreover, compounds cis/trans-1[PF6](n) (n=3, 4) and cis/trans-2[PF6](3) belong to localized compounds by analyzing the experimental characterization results, supported by the TDDFT calculations.