[UO2(NH3)(5)]Br-2 center dot NH3: synthesis, crystal structure, and speciation in liquid ammonia solution by first-principles molecular dynamics simulations

作者：Woidy Patrick; Buehl Michael; Kraus Florian

来源：Dalton Transactions, 2015, 44(16): 7332-7337.

DOI：10.1039/c5dt00180c

Pentaammine dioxido uranium(VI) dibromide ammonia (1/1), [UO2(NH3)(5)]Br-2 center dot NH3, was synthesized in the form of yellow crystals by the reaction of uranyl bromide, UO2Br2, with dry liquid ammonia. The compound crystallizes orthorhombic in space group Cmcm and is isotypic to [UO2(NH3)(5)]Cl-2 center dot NH3 with a = 13.2499(2), b = 10.5536(1), c = 8.9126(1) angstrom, V = 1246.29(3) angstrom(3) and Z = 4 at 123 K. The UO22+ cation is coordinated by five ammine ligands and the coordination polyhedron can be best described as pentagonal bipyramid. Car-Parrinello molecular dynamics simulations are reported for [UO2(NH3)(5)](2+) in the gas phase and in liquid NH3 solution (using the BLYP density functional). According to free-energy simulations, solvation by ammonia has only a small effect on the uranyl-NH3 bond strength.

• 出版日期2015