Preparation of acylpentacarbonylchromate salts and alkoxycarbene pentacarbonyl complexes of chromium employing the pentacarbonylchromate dianion ([Cr(CO)5]2-)

Article abstract of DOI:10.1021/om00152a002

The in situ generated lithium and sodium salts of [Cr(CO)₅]^2- (3) react rapidly and cleanly with a variety of aryl and alkyl acid chlorides at -78°C in THF to provide solutions of the corresponding acylpentacarbonylchromate salts M′[RC(O)Cr(CO)₅] (M′[1], M′ = Li, Na). Subsequent O-methylation of 1 produces Fischer-type alkoxycarbene complexes in yields competitive with established methodologies. This two-step procedure has enabled the preparation of arylmethoxycarbene complexes such as (CO)₅Cr=C(OMe)-{2,5-(OAc)₂C₆H₃} (2g) which are otherwise inaccessible by the standard Fischer synthesis. Alkoxycarbene complexes of molybdenum and tungsten may be prepared analogously from [Mo(CO)₅]^2- and [W(CO)₅]^2-.