Cerium(IV) Nitrate Complexes With Bidentate Phosphine Oxides

The reactions between ceric ammonium nitrate, (NH4)(2)Ce(NO3)(6), (CAN) and the bidentate phosphine oxides, 4,5-bis(diphenylphosphine oxide)-9,9-dimethylxanthene (L1), oxydi-2,1-phenylene bis(diphenylphosphine dioxide) (L-2), 1,2-bis(diphenylphosphino)ethane dioxide (L-3) and 1,4-bis(diphenylphosphino)butane dioxide, L-4 have been investigated. The crystal structures of the molecular Ce(NO3)(4)L-1 (1), and ionic [Ce(NO3)(3)L-2(3)][NO3]center dot CHCl3 (3), [Ce(NO3)(3)L-2(3)][NO3] (4) and the polymeric [Ce(NO3)(3)L-1.5(4)] [NO3] (5) and the cerium(III) complex [Ce(NO3)(2)L-2(1)][NO3] (2) are reported. The thermal stability of the complexes has been examined by thermogravimetry with the gaseous decomposition products analysed by infrared spectroscopy. Evolution of CO2 is found for both Ce(III) and Ce(IV) complexes with the later also forming NO2. The formation of the complexes in solution has been studied by P-31 NMR spectroscopy and further complexes [Ce(NO3)(3)L-2(1)](+) [NO3] and [Ce(NO3)(2)L-3(1)](2+) 2[NO3] identified in CD3CN solution. The complex (1) exists as a single molecular species in solution and is stable in dichloromethane whilst (3) decomposes on standing in both CD2Cl2 and CD3CN to Ce(III) containing species. Complexes of L-2 have been identified by solution P-31 NMR spectroscopy and these decompose in solution to give Ce(NO3)(3)L-2(2). This study represents the first structural characterisations of Ce(IV) complexes with bidentate phosphine oxides.

Automated summary

This study investigates the reactions between ceric ammonium nitrate and bidentate phosphine oxides, and reports the crystal structures and thermal stability of the complexes. NMR spectroscopy is used to study the formation of the complexes in solution.