Kinetics and mechanism of phosphine substitution for CO in (Fe sub 2 Co(CO) sub 9 (CCO)) sup minus
- Northwestern Univ., Evanston, IL (USA)
Rate laws and activation parameters were determined for CO substitution of (PPN)(Fe{sub 2}Co(CO){sub 9}(CCO)) by phosphine ligands. These results along with the dependence of the reaction on the nature of the incoming ligand support an associative mechanism. Previous NMR data indicate that the phosphines selectively attack the Co metal center. Activation parameters are {Delta}H{double dagger} = +7.2 to +10.3 kcal/mol and {Delta}S{double dagger} = {minus}34.0 to {minus}45.5 cal/mol K. The activated complex is proposed to attain an open structure by breaking either a metal-metal or metal-carbon bond. An increase in solvent polarity increases the rate of ligand substitution, whereas a change in the cation from PPN{sup +} to Me{sub 4}N{sup +} has a negligible effect. The rates of reaction were influenced by both the basicity and steric properties of the phosphines.
- OSTI ID:
- 5093789
- Journal Information:
- Journal of the American Chemical Society; (USA), Vol. 111:9; ISSN 0002-7863
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
ORGANIC
PHYSICAL AND ANALYTICAL CHEMISTRY
CARBON MONOXIDE
CHEMICAL REACTIONS
CARBONYLS
IRON COMPLEXES
PHOSPHINES
ACTIVATION ENERGY
CHEMICAL BONDS
CHEMICAL REACTION KINETICS
EXPERIMENTAL DATA
LIGANDS
PH VALUE
STEREOCHEMISTRY
THERMODYNAMICS
CARBON COMPOUNDS
CARBON OXIDES
CHALCOGENIDES
COMPLEXES
DATA
ENERGY
INFORMATION
KINETICS
NUMERICAL DATA
OXIDES
OXYGEN COMPOUNDS
PHOSPHORUS COMPOUNDS
REACTION KINETICS
TRANSITION ELEMENT COMPLEXES
400201* - Chemical & Physicochemical Properties