Iron Versus Ruthenium: Evidence for the Distinct Differences in the Electronic Structures of Hexa-1,3,5-triyn-1,6-diyl-bridged Complexes [Cp*(dppe)M}{-(CC)₃}{M(dppe)Cp*}]⁺ (M = Fe, Ru)

The spectroelectrochemically generated infrared (IR) and near-infrared spectra of the homo-bimetallic, hexa-1,3,5-triyn-L6-diyl-bridged complex cations [{Cp*(dppe)M}(mu-C CC CC C){M(dppe)Cp*}](+) (M = Fe, [1](+); Ru, [2](+)) have been analyzed using density functional theory calculations based on global (BLYP3S) and local (LH2Ot) hybrid functionals. The differences in the number of IR active v(C CC CC C) modes in these complexes are attributed to the distinct electronic localization of the Fe(II)-Fe(III) mixed-valence cation [1](+) on the IR timescale, as opposed to the delocalized electronic character of [2](+).