Formation and reactivity of the Os(IV)-azidoimido complex, PPN[Os(IV)(bpy)(Cl)(3)(N(4))

Reactions between the Os(VI)-nitrido complexes, OsVI(L2)(Cl)3(N)] (L2 = 2,2'-bipyridine (bpy) (1]), 4,4'-dimethyl-2,2'-bipyridine (Me2bpy), 1,10-phenanthroline (phen), and 4,7-diphenyl-1,10-phenanthroline (Ph2phen)), and bis-(triphenylphosphoranylidene)ammonium azide (PPNN3) in dry CH3CN at 60 degrees C under N2 give the corresponding Os(IV)-azidoimido complexes, OsIV(L2)(Cl)3(NN3)]- (L2 = bpy = 2]-, L2 = Me2bpy = 3]-, L2 = phen = 4]-, and L2 = Ph2phen = 5]-) as their PPN+ salts. The formulation of the N42- ligand has been substantiated by 15N-labeling, IR, and 15N NMR measurements. Hydroxylation of 2]- at Nalpha with O<--NMe3.3H2O occurs to give the Os(IV)-azidohydroxoamido complex, OsIV(bpy)(Cl)3(N(OH)N3)] (6]), which, when deprotonated, undergoes dinitrogen elimination to give the Os(II)-dinitrogen oxide complex, OsII(bpy)(Cl)3(N2O)]- (7]-). They are the first well-characterized examples of each kind of complex for Os.