Stabilization of the bis(diphenylphosphino) methanide ion by bridging dirhenium octacarbonyl: [Li(THF)4 ]IRe2(CO)8(Ph2PCHPPh2)]

The anion of Li(THF)₄]Re₂(CO)₈(Ph₂PCHPPh₂)] (1) is formed cleanly by treatment of Re₂(CO)₈(Ph₂PCH₂PPh₂) with LiAlH₄ in tetrahydrofuran (54% yield). Anion 1 is remarkably stable toward all organic electrophiles examined. Whereas protons are added and removed reversibly, 1 is stable to treatment with MeI, Me₃SiCl, Me₃SiCH₂Cl or Ph₂PCl, even under forcing conditions. This behavior sharply contrasts the high reactivity of other mononuclear (Ph₂PCHPPh₂)ML_x complexes.