Transition metal-isocyanide bonding: Photoelectron spectroscopic study of iron tetracarbonyl isocyanide complexes

Journal Article · Mon Dec 31 23:00:00 EST 1984 · Organometallics; (United States)

DOI:https://doi.org/10.1021/om00121a019· OSTI ID:6444695

Beach, D B; Bertoncello, R; Granozzi, G; Jolly, W L

The He I and X-ray photoelectron spectra of the iron tetracarbonyl complexes of methyl, tert-butyl, trimethylsilyl, and phenyl isocyanide have been obtained. The bonding properties of these isocyanides are compared with those of carbon monoxide by using the core-binding energy data to interpret the valence ionization energies. The data show that all the isocyanides have comparable sigma-donor ability and that, in the Fe(CO)/sub 4/CNR complexes, they are significantly weaker sigma donors than carbon monoxide. The stronger sigma-donor character of the coordinated CO ligands is presumably due to the sigma-..pi.. synergism of the Fe-CO bonding. The net interaction of an isocyanide ligand with the iron d orbitals leaves the energy of the d orbitals destabilized relative to Fe(CO)/sub 5/. The data indicate that the relative energies of interaction of the d orbitals with the filled ligand ..pi.. orbitals and the empty ligand ..pi.. orbitals are different in Fe-CO and Fe-CNR bonds, with the interactions of the filled ligand ..pi.. orbitals being relatively more important in Fe-CNR bonds than in Fe-CO bonds. The net electron withdrawal by a coordinated isocyanide ligand, although significant, is much lower than that by a coordinated carbonyl ligand. It is clear that the interactions of transition metals with isocyanides (and probably also with other ligands with similar electronic structures) cannot be adequately described without considering the combined sigma-donor, ..pi..-acceptor, and ..pi..-donor characters of the ligands.

• Research Organization: Univ. of California, Berkeley
• DOE Contract Number: AC03-76SF00098
• OSTI ID: 6444695
• Journal Information: Organometallics; (United States), Journal Name: Organometallics; (United States) Vol. 4:2; ISSN ORGND
• Country of Publication: United States
• Language: English

Related Subjects

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CHEMISTRY
400201* -- Chemical & Physicochemical Properties
400301 -- Organic Chemistry-- Chemical & Physicochemical Properties-- (-1987)
ALKANES
AROMATICS
CARBONYLS
DATA
ELECTRON SPECTROSCOPY
ELEMENTS
EXPERIMENTAL DATA
HYDROCARBONS
INFORMATION
IRON
ISOCYANATES
METALS
NUMERICAL DATA
ORGANIC COMPOUNDS
ORGANOMETALLIC COMPOUNDS
PHOTOELECTRON SPECTROSCOPY
SPECTROSCOPY
TRANSITION ELEMENTS