Infrared spectroscopic studies on the photocatalytic hydrogenation of norbornadiene by group 6 metal carbonyls. 2. The role of the diene and the characterization of (. eta. sup 4 -norbornadiene)(. eta. sup 2 -norbornadiene)M(CO) sub 3 complexes
- Univ. of Nottingham (England)
- Max Planck Institut fuer Strahlenchemie, Ruhr (West Germany)
UV laser flash photolysis of M(CO){sub 6} and (NBD)M(CO){sub 4} (NBD = norbornadiene) is used to generate, respectively, the intermediates M(CO){sub 5}(s) (s = n-heptane; M = Cr, Mo, and W) and ({eta}{sup 4}-NBD)M(CO){sub 3}(s) fac and mer isomers; M = Mo and W. Fast ({mu}s) time-resolved IR spectroscopy is then used to measure the rates of reaction of these intermediates with species likely to be components of the catalytic hydrogenation mixture (e.g., H{sub 2}, NBD, CO, etc.). The measurements show that, for a particular intermediate, the rates of reaction with H{sub 2} and NBD are quite similar. Thus, in a typical catalytic reaction mixture, intermediates are more likely to react with NBD than H{sub 2}, because the concentration of NBD is considerably higher than that of H{sub 2}. Fourier-transform IR is used to monitor the carbonyl species present in solution during photocatalytic deuteration at room temperature. These include the previously unknown complexes fac- and mer-({eta}{sup 4}-NBD)({eta}{sup 2}-NBD)M(CO){sub 3}. In the case of W, it is shown that accumulation of mer-({eta}{sup 4}-NBD)({eta}{sup 2}-NBD)W(CO){sub 3} in the solution frustrates the catalytic deuteration (as monitored by the {nu}(C-D) IR bands of the deuterated products). Furthermore, there is a striking wavelength dependence in the catalytic efficiency of the W system. mer-({eta}{sup 4}-NBD)({eta}{sup 2}-NBD)W(CO){sub 3} is sufficiently stable for them to have isolated a sample (ca, 90% purity). {sup 13}C NMR data support the identification of the complex.
- OSTI ID:
- 7121483
- Journal Information:
- Journal of the American Chemical Society; (USA), Journal Name: Journal of the American Chemical Society; (USA) Vol. 112:3; ISSN 0002-7863; ISSN JACSA
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
360104 -- Metals & Alloys-- Physical Properties
37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CHEMISTRY
400201* -- Chemical & Physicochemical Properties
ALKANES
ALKENES
CARBONYLS
CATALYSTS
CHEMICAL REACTIONS
CHROMIUM
CYCLOALKENES
DATA
DATA ANALYSIS
DIENES
ELEMENTS
ETHANE
EXPERIMENTAL DATA
HYDROCARBONS
HYDROGEN
HYDROGENATION
INFORMATION
INFRARED SPECTRA
KINETICS
MEASURING INSTRUMENTS
MEASURING METHODS
METALS
MOLYBDENUM
NONMETALS
NORBORNADIENE
NUMERICAL DATA
ORGANIC COMPOUNDS
PHOTOCHEMICAL REACTIONS
POLYENES
REACTION KINETICS
SPECTRA
TRANSITION ELEMENTS
TUNGSTEN