The chemistry of tris(thiolato) bridged dimolybdenum compounds in low oxidation states (mostly III) is considered. Various synthetic routes lead to chalcogenide-bridged dinuclear complexes of group 6 metals (mainly Mo). Extensive chemistry of these derivatives is reviewed. Their reactivity towards various reagents such as alkynes, isonitriles, nitriles, propargylic alcohols, azides, hydrazines, carbon disulfide…, demonstrates their ability for activation of small unsaturated molecules through new C–X (X = C, N, O, S…) bonds formation or cleavage.