High resolution x-ray photoelectron spectroscopy study of Cr(CO)6 in the gas phase

Abstract

The gas phase high resolution x-ray photoelectron spectra of the Cr(CO)6 metal complex are presented. The valence electron spectrum and the core level spectra including the associated satellite structures from the Cr, C, and O atoms are discussed. Comparison to free CO and to CO adsorbed on metal surfaces are made. An assignment of the valence levels is achieved using an intensity model. The anomalous dispersion of the narrow band in CO adsorbed on Cu seems to be related to the localization properties of the corresponding 7a1g level in Cr(CO)6. The C1s and O1s shake-up structures are assigned using the Z+1 approximation, electron energy loss data and data from shake-up spectra of free CO. The Cr core level binding energy shifts relative to Cr metal are shown to vary with the subshell. Electronic structure and vibronic calculations are carried out for the ground and C1s and O1s core ionized states. The results for the vibronic coupling constants and for the vibrational excitations confer more with the observations in the electron energy loss spectra of free CO rather than with the photoelectron spectra of free CO. This supports the notion of a, close to complete, charge transfer screening accompanying ligand core ionization of Cr(CO)6.

Valence ionization spectra of group six metal hexacarbonyls studied by the symmetry-adapted cluster-configuration interaction method

“…Other studies identified only three or four peaks in this region. 22,23 The SAC-CI spectrum in Figs. 1-3 indicated four or five peaks in this region with this FWHM.…”

“…They have been widely studied as a prototype for understanding the chemical bonds of organometallic compounds 18,19 or a model for adsorption of carbon monoxide on metal surfaces. 20 On the ionizations in the valence region, He I and He II PES, 21 x-ray PES ͑XPES͒, 22 synchrotron radiation PES ͑SRPES͒, 23,24 and PIES ͑Ref. 25͒ have been reported for Cr͑CO͒ 6 , Mo͑CO͒ 6 , and W͑CO͒ 6 .…”

“…The present calculations well reproduced the ionization energies observed experimentally using PES. [21][22][23][24] A consistent assignment was provided for the experimentally identified peaks of the group six metal hexacarbonyls. This study is a typical example of the application of the SAC-CI method to transition metal compounds.…”

Semiempirical calculations of TiO2 (rutile) clusters

“…A larger energy spread in the calculated spectrum is expected and typical for the INDO method and can be explained by the partial neglect of electron repulsion effects in the INDO method. Therefore, the calculated spectra have been normalized by an energy-spread factor of 0.63, obtained from a comparison between an experimental XPS spectrum of the Cr(C0)6 molecule [32] and a theoretical DOS calculated with the ZINDO program.…”

Processing and properties of (Mo,Cr) oxycarbides from MOCVD

“…If the temperature dependence of the reaction step is described by Eqn [13], from the slope of the fitted line between 310 and 240°C in . The physical meaning of Q c energy is different from that of DH c , i.e.…”