Complex chemistry of reactive organic compounds. 48. .sigma.-Alkyl, .pi.-allyl, and .pi.-olefin coordination of diphenylketene: neutron diffraction studies of the carbonyliron complexes Fe(CO)3[.eta.3:.eta.1-(C6H5)2CCO] and Fe2(CO)6[CH(C6H5)(C6H4)]

Photolysis of pentacarbonyl iron in the presence of diphenylketene yields a novel eta/sup 1/.eta/sup 3/ diphenylketene complex. This compound according to a single-crystal neutron diffraction study, exhibits the heterocumulene precursor in a ..pi..-allyl/sigma-acyl coordination with one phenyl ring engaged in ..pi.. bonding of this ligand to the transition-metal center. Upon treatment of the diphenylketene with excess enneacarbonyldiiron, a dinuclear iron complex is formed in a 77% yield. This molecule was shown by neutron diffraction techniques to contain a bridging hydrocarbon ligand related to the original ketene ligand in the original iron complex by decarbonylation and 1,3-hydrogen shift. Crystallographic data are presented for both the complexes.