Theoretical study of the dissociation of a single carbonyl from chromium hexacarbonyl

Journal Article · Wed Jan 05 04:00:00 EST 1983 · Inorg. Chem.; (United States)

DOI:https://doi.org/10.1021/ic00143a021· OSTI ID:6235542

Sherwood, Jr, D E; Hall, M B

Extended-basis-set Hartree-Fock-Roothaan calculations are reported for the dissociation of a single carbonyl ligand from chromium hexacarbonyl. As expected, the theoretical dissociation energy for the process Cr(CO)/sub 6/ ..-->.. Cr(CO)/sub 5/ + CO (49.8 kcal mol/sup -1/) is larger than the average dissociation energy (29.5 kcal mol/sup -1/). The theoretical dissociation energy for the ion, Cr(CO)/sub 6//sup +/ ..-->.. Cr(CO)/sub 5//sup +/ + CO (30.8 kcal mol/sup -1/), agrees well with the mass spectral value (33.0 kcal mol/sup -1/). Energy partitioning and analysis suggests that ..pi.. bonding accounts for about 25% of the dissociation energy. Plots of the change in electron density as the carbonyl dissociates are reported. Comparison of these plots with those produced from various population analyses suggest that the sigma bond involves primarily a rehybridization of the CO with little net transfer of electron density to the metal. The ..pi.. bond, however, does involve a net transfer of charge from the metal to the carbonyl. Thus, the chromium is found to bear a net positive charge. At very long chromium-carbon distances the carbonyl moiety may act like a sigma-only ligand. Calculations of the change in the force between the C and the O of a free carbonyl as it approaches the Cr(CO)/sub 5/ fragment show that at moderately long Cr-C distances the force is such that the C-O bond distance should be shorter than that of free CO.

• Research Organization: Texas A and M Univ., College Station
• DOE Contract Number: W-7405-ENG-48
• OSTI ID: 6235542
• Journal Information: Inorg. Chem.; (United States), Journal Name: Inorg. Chem.; (United States) Vol. 22:1; ISSN INOCA
• Country of Publication: United States
• Language: English

Related Subjects

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CHEMISTRY
400201* -- Chemical & Physicochemical Properties
BINDING ENERGY
BOND LENGTHS
CARBON COMPOUNDS
CARBON MONOXIDE
CARBON OXIDES
CARBONYLS
CHALCOGENIDES
CHEMICAL REACTION KINETICS
CHROMIUM COMPLEXES
COMPARATIVE EVALUATIONS
COMPLEXES
CONFIGURATION INTERACTION
DATA
DIMENSIONS
DISSOCIATION
DISSOCIATION ENERGY
ELECTRONIC STRUCTURE
ENERGY
HARTREE-FOCK METHOD
INFORMATION
KINETICS
LENGTH
NUMERICAL DATA
OXIDES
OXYGEN COMPOUNDS
REACTION KINETICS
THEORETICAL DATA
TRANSITION ELEMENT COMPLEXES