Reductively induced homolytic carbon–carbon bond cleavage in Co(CO)3(PPh3)(COCF3)

The chemical or electrochemical reduction of the trifluoroacetyl complex Co(CO)3(PPh3)(COCF3) involves a single electron transfer yielding trifluoromethyl radical and an anionic cobalt carbonyl complex. The mechanism is proposed to involve electron transfer followed by initial dissociation of either a carbonyl or phosphine ligand from the 19-electron [Co(CO)3(PPh3)(COCF3)]− anion. The resulting 17-electron intermediate undergoes subsequent one-electron reductive elimination of trifluoromethyl radical by homolytic cleavage of the carbon–carbon bond of the trifluoroacetyl group. The View the MathML sourceCF3 radical can be trapped by either benzophenone anion, forming the anion of α-(trifluoromethyl)benzhydrol, or Bu3SnH, yielding CF3H. The ultimate organometallic product is an 18-electron anion, either [Co(CO)4]− or [Co(CO)3(PPh3)]−, depending upon which ligand is initially lost. Fluorine-containing products were identified and quantitated by 19F NMR while cobalt-containing products were determined by IR.