The reactions between trans-[Os-IV(tpy)(Cl)(2)(NCN)] (1) and PPh3 and between trans-[Os-IV(tpy)(Cl)(2)(NPPh3)](+) (2) and CN- provide new examples of double derivatization of the nitrido ligand in an Os(V])-nitrido complex (Os-VI≡ N). The nitrilic N-bound product from the first reaction, trans-[Os-II(tpy)(Cl)(2)(NCNPPh3)] (3), is the coordination isomer of the first iminic N-bound product from the second reaction, trans-[Os-II(tpy)(Cl)(2)(N(CN)(PPh3))] (4). In CH3CN at 45 ° C, 4 undergoes isomerrization to 3 followed by solvolysis and release of (N-cyano)iminophosphorane, NCNPPh3. These reactions demonstrate new double derivatization reactions of the nitrido ligand in Os-VI≡ N with its implied synthetic utility.