An experimental determination of the Cr-DMB (DMB = 3,3-dimethyl-1-butene) bond energy in Cr(CO)5(DMB): Effects of alkyl substitution on chromium-olefin bond energies in Cr(CO)5(olefin) complexes

David L. Cedeño, Eric Weitz*

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

3 Scopus citations

Abstract

The chromium-olefin complex Cr(CO)5(DMB) (DMB = 3,3-dimethyl-1-butene) has been studied in the gas phase using transient infrared spectroscopy. This complex forms by addition of DMB to photogenerated Cr(CO)5 with a rate constant, kL = (7.0 ± 1.5) × 10-11 cm3 molecule-1 s-1. The bond enthalpy for the DMB-Cr(CO)5 bond has been determined from the kinetics for the decay of Cr(CO)5(DMB) to be 20.1 ± 1.7 kcal/mol at 298 K. An energy decomposition analysis has been performed for a series of Cr(CO)5(olefin) complexes (olefin = DMB, ethylene, propene, 1-butene, 1-hexene, cis-2-butene, trans-2-butene, isobutene, and tetramethylethylene (TME)) using density functional theory. These calculations provide insights into trends in the chromium-olefin bond energy. The results reveal that the trend in bond energies in these complexes correlates with the number and the nature of the alkyl groups around the double bond, and that the dominant factor in this trend is the deformation energy of the olefin and Cr(CO)5, where the deformation energy is the energy required to deform the olefin ligand and the unsaturated metal centered moiety from their isolated ground-state geometries to the geometry they adopt in the bound complex.

Original languageEnglish (US)
Pages (from-to)4651-4660
Number of pages10
JournalJournal of Physical Chemistry A
Volume106
Issue number18
DOIs
StatePublished - May 9 2002

ASJC Scopus subject areas

  • Physical and Theoretical Chemistry

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