Zirconocene−Iridium Hydrido Complexes: Arene Carbon−Hydrogen Bond Activation and Formation of a Planar Square Zr₂Ir₂ Complex

New early−late heterobimetallic hydrides (L2ZrCl)(Cp*Ir)(μ-H)3 (1; L = Cp derivative, Cp* = η5-C5Me5) were synthesized from zirconocene derivatives (L2ZrCl2) and LiCp*IrH3 via a salt elimination reaction and structurally characterized by NMR and X-ray analyses. Upon treatment of 1 with an alkyllithium reagent, hydride abstraction complex 4 underwent thermolytic ligand elimination at the Zr−Ir system to yield a novel planar square complex (L2Zr)2(Cp*Ir)2(μ3-H)4 (2). When a labeling study of the reaction was conducted, it was found that the conversion of 1 to 2 involves rapid aromatic and benzylic C−H activation by a coordinatively unsaturated dinuclear complex (L2Zr)(Cp*Ir)(H)2 (3).