Complex OsH{eta 5 -C5H4(CH2)(2)NMe2}(PiPr(3))(2) (1) reacts with 1 equiv of trifluoromethanesulforlic acid (HOTf) and trifluoromethanesulforlic acid-d(1) (DOTf) to produce the dihydride and hydride-deuteride complexes, [OsHE{eta(5)-C5H4(CH2)(2)NMe2}((PPr3)-Pr-i)(2)]OTf (E = H (2), D (2-d(1))), respectively. Treatment of 2 and 2-d(1) with a second equivalent of HOTf gives [OsHE{eta(5)-C5H4(CH2)(2)NHMe2}((PPr3)-Pr-i)(2)][OTf](2) (E = H (3), D (3-d(1))) as a result of the protonation of the nitrogen atom. While the hydride and deuteride ligands of 2, 2-d(1), 3, and 3-d(1) do not undergo any H/D exchange process with the solvent, in acetone-d(6), the NH proton of 3 and 3-d(1) changes places with a deuterium atom of the solvent to yield [OsHE{eta(5)-C5H4(CH2)(2)NDMe2}((PPr3)-Pr-i)(2)][OTf](2) (E = H (3-Nd-1), D (3-d(2))). Complex 3-Nd-1 can also be obtained from the treatment of complex 2 with DOTf in dichloromethane. No exchange process between the hydride and the ND positions in 3-Nd-1 or between the deuteride and NH positions in 3-d(1) has been observed. Treatment of 3-Nd, and 3-d(1) with sodium methoxide results in a selective reaction of the base with the ammonium group to regenerate 2 and 2-d(1), respectively. Complex 1 also reacts with methyl and methy-d(3) trifluoromethanesulfonate (CH3OTf and CD3OTf, respectively) to give [OsH{eta(5)-C5H4(CH2)(2)NMe2CE3}((PPr3)-Pr-i)(2)]OTf (E = H (4), D (4-d(3))) as a result of the addition of the CE3 (E = H, D) group to the nitrogen atom. Complex 4 has been characterized by an X-ray diffraction analysis. It reacts with a second molecule of CH3OTf or CD30Tf to produce [OsH{eta(5)-C5H4(CH2)(2)NMe3}{CH2CH(CH3)(PPr2)-Pr-i}((PPr3)-Pr-i)][OTf]( 2) (5). Similarly, complex 4-d(3) reacts with a second molecule of CH3OTf or CD3OTf to yield [OsH{eta(5)-C5H4(CH2)(2)NMe2CD3}{CH2CH(CH3)(PPr2)-Pr-i}((PPr3)-Pr-i)][OT f](2) (5-d(3)). In acetonitrile, complex 5 evolves to an equilibrium mixture of the acetonitrile adducts [Os{eta(5)-C5H4(CH2)(2)NMe3}(NCCH3)((PPr3)-Pr-i)(2)][OTf](2) (7) and [Os{eta(5)-C5H4(CH2)(2)NMe3}(NCCH3)(2)((PPr3)-Pr-i)][OTf](2) (8). In methanol or methanol-d(4), complex 4 is not stable and loses trimethylamine to give the vinylcyclopentadienyl derivatives [OsHE(eta(5)-C5H4CH=CH2)((PPr)-Pr-i)(2)]OTf (E = H (9), D (9-d(1))) as a result of the protonation or deutertion of the metallic center and a subsequent Hofmann elimination. Protonation of 4 with HOTf gives the dihydride-trimethylammonium derivative [OsH2{eta(5)-C5H4(CH2)(2)NMe3}((PPr3)-Pr-i)(2)][OTf](2) (10). Treatment of 9 with sodium methoxide produces OsH(eta(5)-C5H4CH=CH2)((PPr3)-Pr-i)(2) (11).