Oxidative addition of organotransition metal complexes to the C-H bonds in organic molecules
Early in 1982 the first examples of direct intermolecular oxidative addition of a transition metal into the C-H bonds of alkanes were reported. Cp*(L)IrH/sub 2/ (Cp* = eta/sup 5/-C/sub 5/Me/sub 5/; L = PMe/sub 3/) was irradiated with ultraviolet light, extruding H/sub 2/ and leading to an intermediate which we formulated as the reactive, coordinatively unsaturated species Cp*Ir(L). This transient species reacts rapidly with all solvents (R-H) to which it has so far been exposed, leading to oxidative addition products Cp*(L)Ir(R)(H). Mechanistic studies suggest a concerted, three-center transition state for the oxidative addition, rather than a more complicated stepwise process (e.g., one involving free radicals). In support of this mechanism, crossover experiments have been used to demonstrate that the R and H groups connected in the substrate molecule remain associated with one another in the final product. In addition, the C-H oxidative addition proceeds with a small but finite isotope effect (k/sub H//k/sub D/ = 1.4), similar to that observed for carbene insertion into C-H bonds.
- Research Organization:
- Lawrence Berkeley Lab., CA (USA)
- DOE Contract Number:
- AC03-76SF00098
- OSTI ID:
- 5490403
- Report Number(s):
- LBL-19572; CONF-8504148-1; ON: DE85012550
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
400301* -- Organic Chemistry-- Chemical & Physicochemical Properties-- (-1987)
ALKANES
AROMATICS
BENZENE
CARBENES
CHEMICAL REACTIONS
COMPLEXES
CYCLOALKANES
CYCLOHEXANE
ELEMENTS
HYDROCARBONS
HYDROGEN PRODUCTION
IRIDIUM COMPLEXES
IRRADIATION
METALS
ORGANIC COMPOUNDS
OXIDATION
POLYMERIZATION
RADICALS
REACTION INTERMEDIATES
RHENIUM COMPLEXES
RHODIUM COMPLEXES
TRANSITION ELEMENT COMPLEXES
TRANSITION ELEMENTS