Reaction of RuCl2(PPh3)(3) with S2- sources yields a family of phosphine-containing Ru-S clusters which have been characterized crystallographically and by MALDI-MS. Ru4S6(PPh3)(4) (Ru-Ru-av = 2.94 Angstrom) has idealized T-d symmetry whereas Ru6S8(PPh3)(6) (Ru-Ru-av = 2.82 Angstrom) adopts the idealized O-h symmetry characteristic of Chevrel clusters. Ru5S6(PPh3)(5) is formally derived by the addition of Ru(PPh3) to one face of Ru4S6(PPh3)(4). In terms of its M-S connectivity, the Ru5S6 cluster resembles a fragment of the FeMo cluster in nitrogenase.