CO-induced, reversible insertion of a terminal imido ligand into an η1η2-isocyanide bridge in the dimolybdenum complex Cp(CO)2Mo(μ-CNPh)Mo(NPh)Cp (Cp = η5-C5H5)

High pressure carbonylation of Cp(CO)2Mo(CNPh)Mo(NPh)Cp-(Mo-Mo) gives a product that has been shown by an X-ray diffraction study to be a metalla-amidinato complex. This means that the originally present terminal phenylimido ligand inserts into an η2, (σ + π)-bonded isocyanide bridge to form a four-membered heterocycle in which a CP(CO)2Mo unit is coordinated by both N atoms, whereas a Cp(CO)3Mo unit is attached to the central carbon atom. In boiling toluene this process is reversed, with release of CO. A by-product in this reaction is a mononuclear Cp(CO)2Mo-amidinato complex bearing a cyclopentadiene group at the central C atom.