A Germanium Isocyanide Complex Featuring (n → π*) Back-Bonding and Its Conversion to a Hydride/Cyanide Product via C–H Bond Activation under Mild Conditions

Reaction of the diarylgermylene Ge­(ArMe6)2 [ArMe6 = C6H3-2,6-(C6H2-2,4,6-(CH3)3)2] with tert-butyl isocyanide
gave the
Lewis adduct species (ArMe6)2GeCNBut, in which the isocyanide ligand displays
a decreased C–N stretching frequency consistent with an n →
π* back-bonding interaction. Density functional theory confirmed
that the HOMO is a Ge–C bonding combination between the lone
pair of electrons on the germanium atom and the C–N π*
orbital of the isocyanide ligand. The complex undergoes facile C–H
bond activation to produce a new diarylgermanium hydride/cyanide species
and isobutene via heterolytic cleavage of the N–But bond.