Iminic N-Bound Iminophosphorano versus Nitrilic N-Bound Iminophosphorano Os(IV) Complexes: A New Double Derivatization of the Nitrido Ligand
摘要:
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 equivalent to 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 degrees 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 equivalent to N with its implied synthetic utility.
Oxo-likereactivity exists for a new series of osmiumcomplexes such as [Os(IV) (bpy)(Cl)3 (NCN)](-) (bpy=2,2'-bipyridine, see structure) containing the cyanoimido ligand. This ligand is formed directly at the metal center by the reaction of Os(VI) -nitrido precursors with tetraethylammonium cyanide. In the cyanoimido complexes there is an extensive electron-transfer chemistry at the metal center and