Carbonyl insertion into zirconium–nitrogen bonds; synthesis and X-ray structure of a carbene complex composed of [Zr(NMe2)4]2 and three Fe(CO)5 units containing Fe→Zr donor–acceptor interactions

The reaction of [Zr(NMe2)4]2 with Fe(CO)5 leads to the multicarbene complex (1) containing two zirconium and three iron atoms. The crystal structure revealed that 1 results from the insertion of five CO groups into ZrN bonds generating chelating biscarbene ligands at two iron atoms and one terminal carbene ligand at the third iron atom. Thus, a planar and a boat-configured ring are formed (A and B) with relatively short FeZr distances of 284 and 282 pm, respectively, indicating early–late transition-metal interactions.