Bis(dimethylglyoximato) complexes of cobalt(II), cobaloxime(II), under mild conditions initiate coupling of α,α,α-trihalomethylbenzenes to form PhCX CX Ph (X Cl), PhCXCXPh (X Cl, Br) and mixtures of halocobaloxime products. Stoichiometry, product distribution, and control experiments suggest that coupling may result from the decomposition of a highly unstable haloalkylcobaloxime intermediate, Co(dmgH) (PhCX )(S(CH ) ). A general mechanism for the formation of this intermediate and its decomposition to the observed products is presented. © 1981. 2 2 2 2 3 2