Trialkylmanganese(II) ate reagents, "R3MnLi", reacted with iodomethyl sulfides to produce thiomethylmanganese reagents, where the manganate serves as a reductant, not an alkylation agent. In this reductive metalation of halides with alkylmanganese ate complexes, the relationship between oxidative addition and the metal-halogen exchange reaction was revealed. A wide variety of modifications of "thiomethylmanganese reagents" thus generated in reactivity could be made.