Cerium(IV) Nitrate Complexes With Bidentate Phosphine Oxides

Abstract

AbstractThe reactions between ceric ammonium nitrate, (NH4)2Ce(NO3)6, (CAN) and the bidentate phosphine oxides, 4,5‐bis(diphenylphosphine oxide)‐9,9‐dimethylxanthene (L1), oxydi‐2,1‐phenylene bis(diphenylphosphine dioxide) (L2), 1,2‐bis(diphenylphosphino)ethane dioxide (L3) and 1,4‐bis(diphenylphosphino)butane dioxide, L4 have been investigated. The crystal structures of the molecular Ce(NO3)4L1 (1), and ionic [Ce(NO3)3L32][NO3]⋅CHCl3 (3), [Ce(NO3)3L32][NO3] (4) and the polymeric [Ce(NO3)3L41.5] [NO3] (5) and the cerium(III) complex [Ce(NO3)2L12][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 31P NMR spectroscopy and further complexes [Ce(NO3)3L12]+[NO3]− and [Ce(NO3)2L13]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 L2 have been identified by solution 31P NMR spectroscopy and these decompose in solution to give Ce(NO3)3L22. This study represents the first structural characterisations of Ce(IV) complexes with bidentate phosphine oxides.