Pyrimidine-2,4-dithiol [HL 1 = (HS)2C4H2N2] and pyridine-2-thiol [HL 2 = (HS)C5H4N] form the osmium clusters [Os3(µ-H)(CO)10}2(µ-S2C4H2N2)] and [Os3(µ-H)(CO)10(µ-SC5H4N)], each of which contain chelating µ,η1-thiolate ligands and hydride bridges across common edges of the osmium triangles. In the former complex two osmium triangles are linked together by the pyrimidinedithiolato ligand.