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(μ‐NC)Ru(4,4’‐dmbpy)2(μ‐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(μ‐NC)Ru(bpy)2(μ‐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. Two series of trinuclear cyanidometal‐bridged compounds with cis/trans configuration were synthesized and fully characterized in this work. The experimental results show that the trans‐configuration and the ligand with high electron‐donating ability of the central cyanidometal bridge are more favorable for MMCT in trinuclear cyanidometal‐bridged mixed valence compounds, and these mixed valence compounds all belong to localized compounds, supported by the TDDFT calculations.