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

Abstract

Abstract Uranyl tris-(carbohydrazide) nitrate [UO2((N2H3)2CO)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)2CO in a molar ratio of 1 to 3 in an neutral medium. The substance was characterized by elemental, thermal analysis and IR and 15N 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) Å, b = 12.005(1) Å, c = 10.842(1) Å, β = 109.15(1)○, V = 1868.11 Å3, Z = 4, SG = Cc. The type of carbohydrazide coordination was additionally confirmed by 15N MAS CP NMR and IR spectroscopy. In the complex ion [UO2((N2H3)2CO)3]2+ three carbohydrazide ligands coordinate to UO2 2+ 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)2CO)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 Å and the angle between sections is 140○. The substance [UO2((N2H3)2CO)3](NO3)2 is thermally stable up to 215 ℃ and then decomposes with an explosion.