Bis(dimethylglyoximato) complexes of cobalt(II), cobaloxime(II), under mild conditions initiate coupling of α,α,α-trihalomethylbenzenes to form PhCX2CX2Ph (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)2(PhCX2)(S(CH3)2). A general mechanism for the formation of this intermediate and its decomposition to the observed products is presented. © 1981.