Nitrido-ruthenium(VI) and -osmium(VI) complexes containing chelating multianionic (N, O) ligands. Synthesis, crystal structures and reactions with triphenylphosphine

A series of nitrido-ruthenium(VI) and -osmium(VI) complexes containing chelating di-, tri- and tetra-anionic ligands was synthesized by ligand substitution reaction in methanol under room conditions in the presence of 2,6-dimethylpyridine. All the newly prepared complexes are air-stable diamagnetic solids. The crystal structures of seven complexes have been established by X-ray crystallography. The RuN (1.615–1.594 Å) and the OsN (1.612–1.621 Å) bond distances are rather insensitive to the electron-donating power of the auxiliary ligands. All the nitridoruthenium(VI) complexes react spontaneously with triphenylphosphine, and the intermediate [RuIV(NPPh3)L1(py)Cl] has been isolated and characterized spectroscopically for the reaction with [RuVIN(L1)Cl]. However, for those nitridoruthenium(VI) complexes bearing the tri- (L2)3– and tetra-anionic (L3,4)4– ligands, the phosphiniminatoruthenium(IV) intermediate undergoes further reaction with pyrazole to generate a bis(pyrazole)ruthenium(IV) complex as the product.