Uranyl tris-(carbohydrazide) nitrate [UO2((N2H3)2CO)3](NO3)2: synthesis, structure and properties

Uranyl tris-(carbohydrazide) nitrate [UO2 ((N2H3)(2)CO)(3)](NO3)(2) was prepared by the reaction of water solution of dioxouranium(VI) nitrate UO2(NO3)(2)(H2O)(6) with ethanol solution of carbohydrazide (N2H3)(2)CO in amolar ratio of 1 to 3 in an neutral medium. The substance was characterized by elemental, thermal analysis and IR and N-15 MAS CP NMR spectroscopy. Ab initio crystal structure determination was carried out using X-ray powder diffraction techniques. The compound crystallizes in monoclinic lattice with unit cell parameters: a = 15.193(1) angstrom, b = 12.005(1) angstrom, c = 10.842(1) angstrom, beta = 109.15(1)degrees, V = 1868.11 angstrom(3), Z = 4, SG = Cc. The type of carbohydrazide coordination was additionally confirmed by N-15 MAS CP NMR and IR spectroscopy. In the complex ion [UO2 ((N2H3)(2)CO)(3)](2+) three carbohydrazide ligands coordinate to UO22+ through oxygen and nitrogen forming three five-membered chelate rings. The carbohydrazide rings are tuned to the equatorial plane of complex. The crystal structure consists of zig-zag chains of [UO2((N2H3)(2)CO)(3)](2+) cations stretched along c-axis. The cations in the chain are linked by the hydrogen bonds between the cations themselves. The anions are located in the pores between chains and participate in hydrogen bonding between adjacent chains and additionally link the chain sections. The length of the chain section is 5.768 angstrom and the angle between sections is 140 degrees. The substance [UO2((N2H3)(2)CO)(3)](NO3)(2) is thermally stable up to 215 degrees C and then decomposes with an explosion.