An investigation of coordinatively unsaturated metal carbonyls using time-resolved infrared spectroscopy
This dissertation details the work done implementing a state of the art (100 ns temporal response with sub wavenumber frequency resolution) time resolved infrared (TRIR) spectrophotometer to study the reactive chemical species produced by pulsed laser photolysis which are proposed to be related to the key intermediates generated in thermal reactions. Photolysis (308 nm XeCl Excimer laser) of ambient temperature isooctane solutions of Ru[sub 3](CO)[sub 12] produced an intermediate proposed to be the Ru[sub 3](CO)[sub 11] species observed by M.S. Wrighton in low temperature matrices. This intermediate was found to react with CO with a second order rate constant, K[sub co], of 2.4 x 10[sup 9] M[sup [minus]1]s[sup [minus]1]. It was also found to react with donating solvents, such as THF, even more rapidly. The reaction with THF, k[sub L], was found to be 6.1 x 10[sup 9] M[sup [minus]1]s[sup [minus]1]. The rate of dissociation, k[sub L], was 2 x 10[sup 6] s[sup [minus]1]. It is of interest that the associative rates are approaching the calculated diffusion controlled limits for bimolecular reactions in isooctane (k[sub d] = 1.3 x 10[sup 10] M[sup [minus]1]s[sup [minus]1]). The second project discussed concerns the nature of intermediates produced in the migratory insertion reaction of CO with the model compounds CH[sub 3]Mn(CO)[sub 5] and CpFe(CO)[sub 2]CH[sub 3]. It was found that the nominally coordinatively unsaturated intermediates were solvated, especially in more donating solvents such as THF. The acyl intermediates, CH[sub 3]COMn(CO)[sub 4](S) and CpFe(CO)(S)COCH[sub 3], were relatively unreactive in cyclohexane, having K[sub co] values of 5.6 x 10[sup 3] M[sup [minus]1]s[sup [minus]1] and <10[sup 5] M[sup [minus]1]s[sup [minus]1], respectively. Rates for isomerization to the corresponding methyl compounds were 6.0 s[sup [minus]1] and 5.7 x 10[sup 4] s[sup [minus]1].
- Research Organization:
- California Univ., Santa Barbara, CA (United States)
- OSTI ID:
- 5649592
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
400201* -- Chemical & Physicochemical Properties
400500 -- Photochemistry
ABSORPTION SPECTROSCOPY
CARBON COMPOUNDS
CARBON MONOXIDE
CARBON OXIDES
CARBONYLS
CHALCOGENIDES
CHEMICAL REACTION KINETICS
CHEMICAL REACTIONS
COMPLEXES
DECOMPOSITION
DISSOCIATION
ELECTROMAGNETIC RADIATION
ISOMERIZATION
KINETICS
LASER RADIATION
MANGANESE COMPLEXES
ORGANIC COMPOUNDS
ORGANOMETALLIC COMPOUNDS
OXIDES
OXYGEN COMPOUNDS
PHOTOCHEMICAL REACTIONS
PHOTOLYSIS
RADIATIONS
REACTION INTERMEDIATES
REACTION KINETICS
RESOLUTION
RUTHENIUM COMPLEXES
SPECTROSCOPY
TIME RESOLUTION
TIMING PROPERTIES
TRANSITION ELEMENT COMPLEXES