Hemilability of the primary amine–metal bond in polyamine-(Group 6) metal carbonyl complexes

A series of cis-LM(CO)4 complexes was prepared by reaction of non symmetrical diamines (L=R1R2N–(CH2)n–NH2, with R1 and R2=alkyl groups) with metal carbonyls M(CO)6, (M=Cr, Mo, W). Only the primary amine of these complexes reacted with mono or dialdehydes, thus leading to mono or dinuclear imine complexes, stabilized by the metal moiety and strongly suggesting that the NH2–metal bond has a hemilabile character.