The Pd2X2(dmpm)(2) complexes [X = Cl (1a), Br (1b), I (1c); dmpm = bis(dimethylphosphino)methane. In all the dipalladium complexes mentioned in this paper, the dmpm, depm, and dppm ligands (unless stated otherwise) are bridging, but for convenience the mu-symbol is omitted.] react with H2S to yield H-2 and the bridged-sulfido complexes Pd2X2(mu-S)(dmpm)(2) (2a-c), of which 2a and 2b are structurally characterized. With la, two rapid reversible equilibria are observed by NMR spectroscopy below -30 degrees C, and two reaction intermediates are detected; both are likely hydrido(mercapto) species. Reaction of 1a with 1 equiv of elemental sulfur also yields 2a. The reaction of 1a with COS results in the initial formation of Pd2Cl2(mu-COS)(dmpm)(2) (3) that undergoes decarbonylation to yield 2a and Pd2Cl2(mu-CO)(dmpm)(2) (4), which is also formed via reversible insertion of the CO into the Pd-Pd bond of la. The solid-state molecular structure of the previously reported complex Pd2Cl2(mu-CS2)(dmpm)(2) (5), together with solution NMR data for 3 and 5, reveal that the bridging heterocumulene ligands coordinate in an eta(2)-C,S fashion. Analogous findings were made for the corresponding Pd2X2(depm)(2) complexes [X = Cl (1a'), Br (1b'), I (1c'); depm = bis(diethylphosphino)methane], although no mu-COS species was detected. The Pd2X2(mu-S) (depm)(2) complex was structurally characterized. Differences in the chemistry of the previously studied, corresponding dppm systems (dppm = bis(diphenylphosphino)methane) are discussed.