The coordination chemistry of 2,4-di(tert-butyl)pentadienyl revisited

The electronic and molecular structures of the half-open ferrocene [(η5-Pdl′)Fe(η5-Cp″)] and its closed analogue [(η5-Cp′)Fe(η5-Cp″)] (Cp′ = 1,3-(Me3C)2C5H3) were compared. Both complexes can be cleanly oxidized to give the half-open ferrocenium and closed ferrocenium, respectively; but they are low spin molecules with different electronic ground states. 119