Triple bonds between iron and heavier group-14 elements in the AFe(CO)(3)(-) complexes (A = Ge, Sn, and Pb)

Heteronuclear transition-metal-main-group element carbonyl anion complexes of AFe(CO)(3)(-) (A = Ge, Sn, and Pb) are prepared using a laser vaporization supersonic ion source in the gas phase, which were studied by mass-selected infrared (IR) photodissociation spectroscopy. The geometric and electronic structures of the experimentally observed species are identified by a comparison of the measured and calculated IR spectra. These anion complexes have a (2)A(1) doublet electronic ground state and feature an ARFe triply bonded C-3v structure with all of the carbonyl ligands bonded at the iron center. Bonding analyses of AFe(CO)(3)(-) (A = C, Si, Ge, Sn, Pb, and Fl) indicate that the complexes are triply bonded between the valence np atomic orbitals of bare group-14 atoms and the hybridized 3d and 4p atomic orbitals of iron.