[Closo-B10h8-1,10-(cn)2]2-< /SUP> As a Conduit of Electronic Effects: Comparative Studies of Fe???Fe Communication in [{(5-Cp)(dppe)fe}2{2-(nc-x-cn)}] N+ (n=0, 2)

Electronic communication between Fe centers in the diiron complexes [{(eta(5)-Cp)(dppe)Fe}(2){mu(2) -(NC-X-CN)}](n+) (n = 0, 2) in which X = [-B10H8-](2-), - C6H4-, -C8H12- and -C2B10H10- was investigated by spectroscopic (UV-vis and IR), electrochemical (CV and DPV), and single-crystal XRD methods. All experimental results were supported by a DFT computational analysis (B3LYP/Def2SVP) of model complexes that included two other closo-boranes: X = -C2B8H8- and [-B12H10-](2-). The DFT analysis focused on the geometry, electronic excitations, IR spectra, charge and spin delocalization, and intramolecular spin-spin exchange interactions in the series of all six complexes and their singly and doubly oxidized analogues. The results demonstrate that [closo-B10H8-1,10-diyl](2-) has the best ability among the closo-boranes to mediate electronic effects similar to those of 1,4-phenylene. This is evident from the observed separation of one-electron-oxidation waves (similar to 70 mV) and comparable S-T energy gaps in the doubly oxidized species.