Gas-phase observation and CO substitution kinetics of cis-Cr(CO)/sub 4/(C/sub 2/H/sub 4/)/sub 2/ by time-resolved IR absorption spectrometry
Olefin complexes of metal carbonyl fragments have theoretical importance and play a role in numerous catalytic systems. Theory suggests an interesting trend in bond strengths for the bis-olefin and diene complexes of the 16-electron group VI (group 6) carbonyl fragments. Bis-olefin complexes of M(CO)/sub 4/ (M = Cr, Mo, W) are generally thought to be more stable than eta/sup 4/-diene complexes. Experiments show that the mono- and bis-olefin complexes of molybdenum and tungsten carbonyls are quite stable but such examples for chromium are rare. Only one Cr(CO)/sub 4/(olefin)/sub 2/ complex is known and it is stabilized by relief of ring strain in the uncomplexed olefin. Interestingly, the analogous eta/sup 4/ complexes of nonconjugated dienes are generally quite stable for all three rows of group VI (group 6). This paper reports the first gas-phase observation and infrared spectral characterization of Cr(CO)/sub 4/(C/sub 2/H/sub 4/)/sub 2/. This complex is unstable and reacts with CO by dissociative substitution. They follow the kinetics of this process by time-resolved IR absorption spectrometry, extracting a unimolecular decay constant orders of magnitude larger than the reported solution value for Cr-(CO)/sub 4/(eta/sup 4/-butadiene), in an apparent conflict with elementary theory as cited above.
- Research Organization:
- Purdue Univ., West Lafayette, IN
- OSTI ID:
- 6970513
- Journal Information:
- J. Am. Chem. Soc.; (United States), Journal Name: J. Am. Chem. Soc.; (United States) Vol. 109:4; ISSN JACSA
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
400201* -- Chemical & Physicochemical Properties
ABSORPTION SPECTROSCOPY
ALKENES
CARBON COMPOUNDS
CARBON MONOXIDE
CARBON OXIDES
CARBONYLS
CATALYSTS
CHALCOGENIDES
CHEMICAL REACTION KINETICS
CHEMICAL REACTIONS
CHROMIUM COMPLEXES
COMPLEXES
DATA
EXPERIMENTAL DATA
FLUIDS
GASES
HYDROCARBONS
INFORMATION
INFRARED SPECTRA
KINETICS
NUMERICAL DATA
ORGANIC COMPOUNDS
OXIDES
OXYGEN COMPOUNDS
REACTION KINETICS
SPECTRA
SPECTROSCOPY
TRANSITION ELEMENT COMPLEXES