ACTIVATION OF REDUCING AGENTS. SODIUM HYDRIDE CONTAINING COMPLEX REDUCING AGENTS. XIV. NaCoCO4 AS AN SRN1 NUCLEOPHILE IN THE CARBONYLATION OF ARYL HALIDES BY CoCRACO AT ATMOSPHERIC PRESSURE. NEW PREPARATION OF NaCoCO4 BY NaH REDUCTION OF DICOBALT OCTACARBONYL

Article abstract of DOI:10.1016/S0022-328X(00)84589-1

The only detectable cobalt carbonyl species present in CoCRACO (NaH/t-AmONa/Co(OAc)2/CO) (t-Am = tert-amyl) is NaCoCO4.The simultaneous presence of NaH, t-AmONa, NaCoCO4 and some soluble, non-carbonyl, cobalt species allows highly catalytic carbonylation of C6H5Br under very mild conditions, while NaCoCO4 alone can carbonylate C6H5Br under irradiation (350 nm).In the presence of t-AmONa, the reaction is highly catalytic with respect to cobalt.These results strongly suggest a S_RN1 mechanism.It is suggested that catalytic carbonylations with CoCRACO take place by a S_RN1, electron-initiated, reaction.A new, very convenient method of preparation of NaCoCO4 by quantitative reduction of Co2CO8 with NaH is also described.