Among the reported functionalized complexes, oxo and nitrido ruthenium or osmium complexes containing multidentate nitrogen-based ligands have proven to be especially valuable in mechanistic and oxidative catalytic studies. During the last decade the chemistry of inorganic and organometallic complexes with phosphine ligands has been well developed to apply them to catalysts. Therefore it is of interest to combine these two characteristics to prepare oxo complexes surrounded by the phosphine ligands. A general way to synthesize Ru-oxo complexes can be started from the related Ru-chloro species via the corresponding Ru-aquo complexes. Oxidation of the Ru-aquo complexes by a powerful one-electron oxidant like (NH4)2Ce(NO3) (CAN) can lead to the formation of the final products. Accordingly we prepared and characterized ruthenium di-chloro complexes, [Ru(dppm)2Cl2] and [Ru(dppe)2Cl2], by using the reaction of [Ru(PPh3)2Cl2] with the dppm or dppe ligand (PPh3: triphenylphosphine, dppm: 1,1-bis(diphenylphosphino)methane, dppe: 1,2-bis(diphenylphosphino)ethane). A ruthenium di-aquo complex, [Ru(dppm)2(H2O)2](PF6)2, can be obtained by adding AgClO4 to the [Ru(dppm)2Cl2] complex followed by precipitating with saturated NH4PF6 solution. CAN in HClO4 was added into the di-aquo complex and the residue was put into the refrigerator. The crystals obtained by diffusion method from acetone/water show the formation of an unexpected complex rather than the desired ruthenium di-oxo species. In organic chemistry CAN has been known to catalyze the ring opening reaction of different epoxides through the formation of nitrate compound in aprotic solvent, which is a key intermediate in the stereoselective syntheses and is useful for a variety of oxidative transformations. The photochemical reaction of CAN with olefins also produced 1,2nitrate adduct via the initial formation of nitrate radical. It is quite interesting to show that CAN can be used to prepare the nitrate complexes in coordination chemistry. Here we found out that the reaction of CAN in perchloric acid with the di-aquo complex gave the unusual nitrate complex rather than the di-oxo complex. In the reaction it is presumed that the more labile aquo group in the di-aquo complex can be quickly substituted by the nitrate anion in a bi-dentate fashion, which is more favorable in entropy. The structure of the nitrate complex, which turned out to be [Ru(dppm)2(O2NO)][ClO4], has been determined from X-ray diffraction. The perspective view with the numbering scheme of the atoms is shown in Figure 1. The complex consists of discrete [Ru(dppm)2(O2NO)] and ClO4, which contains a ruthenium atom surrounded by two chelating diphosphine ligands and the nitrate ligand. The presence of the nitrate ligand coordinated to the ruthenium metal was confirmed by a singlet resonance at 13.8 ppm in the N NMR spectrum and that of the perchlorate anion by a sharp singlet peak at 1.01 ppm in the Cl NMR spectrum. The magnitude of the splitting of peaks at 1435 and 1232 cm−1 observed in the FT IR spectrum re-confirmed that the nitrate ligand coordinated to the metal in a bi-dentate way. The coordination polyhedron around the ruthenium metal is described as a severely distorted octahedron. Selected bond distances and angles listed in Table 1 are comparable with other structurally characterized complexes containing the dppm ligand. The Ru-P bond distances range from 2.277(1) to 2.393(1) A. The phosphorous atoms coordinated to ruthenium metal deviate strongly from a square planar arrangement as noted by the P1-Ru-P2 and P3-Ru-P4 bond angles of less than 90 (70.76(3) and 70.35(3), respectively) for two phosphorous atoms bonded to the ruthenium metal cis to one another and by the P1-Ru-P4 and P2-Ru-P3 angles of less than 180 (103.8(1) and 102.7(1), respectively) for those in the opposite position.