Palladium and Platinum Complexes of a Benzannulated N-Heterocyclic Plumbylene with an Unusual Bonding Mode

Reaction of the N,N′-diisobutyl-substituted benzannulated N-heterocyclic plumbylene (NHPb) 1 with [Pd(PPh3)4] and [Pt(PPh3)4] gave the complexes [M(NHPb)(PPh3)3] (M = Pd [2], Pt [3]). X-ray diffraction studies of both complexes showed an angle of ∼125° between the plumbylene plane and the transition-metal–Pb axis, indicating coordination of the transition metal to the empty π orbital of the plumbylene Pb atom. The experimentally determined metric parameters of complexes [2] and [3] are discussed on the basis of DFT calculations.