Title
Experimental and Theoretical Investigation into the Formation and Reactivity of M(Cp)(CO)₂(CO₂) (M = Mn or Re) in Liquid and Supercritical CO₂ and the Effect of Different CO₂ Coordination Modes on Reaction Rates with CO, H₂, and N₂
Abstract
Nanosecond time-resolved infrared spectroscopy (TRIR) has been used to study the coordination of CO₂ to the metal centers by UV photolysis of M(Cp)(CO)₃ (M = Mn or Re) in liquid or supercritical CO₂ (scCO₂) solution, which led to the formation of the CO₂ complexes M(Cp)(CO)₂(CO₂). Differences between the positions of the ν(C−O) IR bands of the CO ligands in Mn(Cp)(CO)₂(CO₂) and Re(Cp)(CO)₂(CO₂) suggest that the CO₂ ligand has different coordination modes to the metal centers in these complexes. The kinetic data and the IR spectra of the CO₂, Xe, and heptane complexes provided evidence that the CO₂ coordination mode is η¹-O end-on bound in Mn(Cp)(CO)₂(CO₂), and η²-C,O side-on bound in Re(Cp)(CO)₂(CO₂). These different coordination modes lead to dramatic differences in reactivity with CO, H₂, and N₂, with the Re complexes being significantly less reactive. To provide more evidence for the nature of the CO₂ binding modes, a series of DFT calculations were performed at the B3LYP/SDD-6-311G** level. The calculations supported the experimentally proposed CO₂ coordination modes. A significant charge transfer from Re to CO₂ occurs, resulting in partial oxidation of Re.
Disciplines
Chemistry
Recommended Citation
Yang, J., N’Guessan, B.R., Dedieu, A., Grills, D.C., Sun, X., & George, M.W. (2009) ‘Experimental and theoretical investigation into the formation and reactivity of M(Cp)(CO)₂(CO₂) (M = Mn or Re) in liquid and supercritical CO₂ and the effect of different CO₂ coordination modes on reaction rates with CO, H₂ and N₂’.Organometallics, 28(11), 3113-3122
Digital Commons Citation
Yang, Jixin; N'Guessan, Boka R.; Dedieu, Alain; Grills, David C.; Sun, Xue-Zhong; and George, Michael W., "Experimental and Theoretical Investigation into the Formation and Reactivity of M(Cp)(CO)₂(CO₂) (M = Mn or Re) in Liquid and Supercritical CO₂ and the Effect of Different CO₂ Coordination Modes on Reaction Rates with CO, H₂, and N₂" (2009). Advanced Materials Research Laboratory. Paper 10.
http://epubs.glyndwr.ac.uk/amrl/10
Comments
Metadata only available from this repository. Copyright © 2009 American Chemical Society This article was originally published in the Journal of Organometallics published by the American Chemical Society in 2009. The definitive version is available at http://pubs.acs.org/