A molecular beam photoionization mass spectrometric study of Cr(CO){sub 6}, Mo(CO){sub 6}, and W(CO){sub 6}
- Ames Laboratory, United States Department of Energy, and Department of Chemistry, Iowa State University, Ames, Iowa 50011 (United States)
The photoionization efficiency (PIE) spectra for M(CO){sub n}{sup +} (n=0{endash}6) from M(CO){sub 6}, M=Cr, Mo, and W, have been measured in the photon energy range of 650{endash}1600 {Angstrom}. Based on the ionization energies for M(CO){sub 6} and appearance energies (AEs) for M(CO){sub n}{sup +} (n=0{endash}5) determined here, we have obtained estimates for the sequential bond dissociation energies (D{sub 0}) for CO{endash}M(CO){sub n{minus}1}{sup +} (n=1{endash}6). The comparison between the D{sub 0} values for the Cr(CO){sub 6}{sup +} system obtained here and in the recent collisional induced dissociation and theoretical studies suggests that D{sub 0} values for CO{endash}M(CO){sub n{minus}1}{sup +} (n=3{endash}6) based on this PIE experiment are reliable. The PIE results reveal the general trend for individual D{sub 0} values that D{sub 0}[CO{endash}Cr(CO){sub n{minus}1}{sup +}]{lt}D{sub 0}[CO{endash}Mo(CO){sub n{minus}1}{sup +}]{lt}D{sub 0}[CO{endash}W(CO){sub n{minus}1}{sup +}] (n=3{endash}6). The comparison of the first D{sub 0} values for M(CO){sub 6}{sup +} obtained here and those for M(CO){sub 6} reported previously provides strong support for the theoretical analysis that the importance of relativistic effects, which give rise to more efficient M to CO {pi}-back-donation in M(CO){sub 6}, is in the order W(CO){sub 6}{gt}Mo(CO){sub 6}{gt}Cr(CO){sub 6}. {copyright} {ital 1997 American Institute of Physics.}
- Research Organization:
- Ames National Laboratory
- DOE Contract Number:
- W-7405-ENG-82
- OSTI ID:
- 542171
- Journal Information:
- Journal of Chemical Physics, Vol. 107, Issue 12; Other Information: PBD: Sep 1997
- Country of Publication:
- United States
- Language:
- English
Similar Records
Infrared spectroscopic studies on the photocatalytic hydrogenation of norbornadiene by group 6 metal carbonyls. 1. The role of H sub 2 and the characterization of nonclassical dihydrogen complexes, (. eta. sup 4 -norbornadiene)M(CO) sub 3 (. eta. sup 2 -H sub 2 )
Photodissociation of Cr(CO)/sub 6/ in a molecular beam at 248 nm: Observation of primary and secondary photoproducts by mass spectrometry