The compounds trans-M(H)(SPh)(dppe)(2) (M = Ru (1Ru), Os (1Os); dppe = 1,2-bis(diphenylphosphino)ethane) are synthesized by reaction of NaSPh with trans-[Ru(H-2)(H)(dppe)(2)]BPh4 or with trans-Os(H)(Br)(dppe)2 in THF under Ar. They are characterized by H-1 and P-31 NMR, IR, FAB mass spectroscopy, elemental analyses, and cyclic voltammetry. The crystal structure determination of 1Ru verifies the trans, octahedral geometry, which is distorted by ring-ring interactions. The thiophenoxide ligand is coordinated to the metal in a bent configuration, with the phenyl ring sandwiched between two phenyl rings of one of the dppe ligands. The reaction of complexes 1 with 1 equiv of HBF4 . Et2O leads to the formation of the very reactive hydride thiol complexes trans-[M(H)-(HSPh)(dppe)(2)]BF4 (M = Ru (2Ru), Os (2Os)). Analogous complexes to 1Os and 2Os with SC6H4-4-F -F instead of SPh are also described. In all cases there is no evidence for the existence of the tautomeric dihydrogen complex trans-[M(H-2)(SAr)(dppe)(2)](+). Zn the presence of excess acid the diprotonated complex trans-[Os(H-2)(HSPh)-(dppe)(2)](BF4)(2) (3Os) is formed at 233 K where the T-1(min) of the H-2 ligand at 400 MHz is similar to 34 ms so that 0.98 less than or equal to d(HH) less than or equal to 1.24 Angstrom. Under certain conditions the labile PhSH ligand of 3Os is substituted by water to give trans[Os(H-2)(OH2)(dppe)(2)](BF4)2 (4OS). The thiol complexes 2 react rapidly with H-2(g) to give the complexes trans[M(H-2)H(dppe)(2)]BF4 (5Ru, 5Os). Complexes 3Os and 4Os also react with H-2 to give 5Os. N-2 and O-2(1 atm) displace the thiol in 2Os in CH2Cl2 to produce trans-[Os(H)(L)(dppe)(2)](+) (L eta(1)-N-2 (6Os), eta 2-O-2(7OS)). trans[Os(H)(O-2)(dppe)(2)]OTf . 3C(6)H(6) is characterized by X-ray diffraction.