31722-42-6Relevant articles and documents
Carbonylation-decarbonylation reactions of the carbomethoxymethylcobalt complexes CH3O2CCHRCO(CO)3l (R = H, CH2CO2CH3; L = CO, PPh3) and their acyl derivatives
Kovacs, Istvan,Szalontai, Gabor,Ungvary, Ferenc
, p. 115 - 123 (1996)
The primary and secondary alkyl- and acylcobalt carbonyl complexes CH3O2CCHRCo(CO)3L and CH3O2CCHRC(O)Co(CO)3L (R = H or CH2CO2CH3; L = CO, PPh3) (1-8) have been prepared and studied by a variety of IR and 1H, 13C{1H}, 31P{1H} and 17O{1H} NMR spectroscopic methods. Unlike their primary analogues, all the secondary complexes readily undergo a reversible carbonylation-decarbonylation reaction. The new alkyl complex trans-CH3O2CCH2Co(CO)3PPh3 (3) was characterized in solution, and exhibited remarkably different properties from the well-known homologue trans-CH3CH2O2CCH2Co(CO)3PPh3, i.e. it readily decomposes to [Co(CO)3PPh3]2, suggesting homolytic dissociation of the carbon-cobalt bond, and its IR spectrum exhibits an organic ν(CO) absorbance at an unusually low frequency, pointing to an oxygen-cobalt interaction. The corresponding acyl complex trans-CH3O2CCH2C(O)Co(CO)3PPh3 (4) was isolated as a stable solid, but smoothly decarbonylated in solution to 3. Multinuclear NMR spectroscopic monitoring of this reaction suggested the intermediate formation of cis-CH3O2CCH2Co(CO)3PPh3, providing the first direct evidence for alkyl migration in cobalt carbonyl complexes.
