Unconventional hydrogen-bond interactions involving metal hydrides as proton acceptors from N-H bonds have been recently discovered in mononuclear organometallic systems. The work herein reported on H2Os3(CO)(10)L (L= NH2Et, NHEt2) suggests that this type of interaction may be even more important in cluster chemistry in directing the stereochemistry of the products as well as affecting the intramolecular ligand exchange processes.