Uranyl Halides from Liquid Ammonia: [UO₂(NH₃)₅]Cl₂·NH₃ and [UO₂F₂(NH₃)₃]₂·2NH₃ and Their Decomposition Products [UO₂Cl₂(NH₃)₃] and [UO₂F₂(NH₃)₃]

Abstract

Additional Computational Details PCM and NBO calculations Starting from the gas-phase BLYP/SDD/6-311+G** equilibrium structures, [UO 2 L 5 ] 2+ (L = H 2 O, NH 3) were re-optimised using the polarisable continuum model in its integral equation formalism (IEF-PCM), 1 as implemented in Gaussian 09. 2 For L = H 2 O, standard solvent parameters of water were used, for ammonia we employed the static dielectric constant of liquid ammonia at 20ºC ( = 16.6), 3 the same dynamic dielectric constant as water, 4 and a solvent radius of 2.5 Å. 5 Natural bond orbital analyses 6 employed the Gaussian NBO version 3.1 as implemented in Gaussian 09. CPMD simulations The same methods and basis sets as in our previous studies of uranyl complexes 7 were employed. Car-Parrinello molecular dynamics (CPMD) 8 simulations were performed using the BLYP functional 9 and norm-conserving pseudopotentials that had been generated according to the Troullier and Martins procedure 10 and transformed into the Kleinman-Bylander form. 11 For uranium, the semicore (or small-core) pseudopotential was employed that had been generated and validated in reference 12. Periodic boundary conditions were imposed using cubic supercells with a lattice contant of 13.22 Å. Kohn-Sham orbitals were expanded in plane waves at the -point up to a kinetic energy cutoff of 80 Ry. Simulations were performed in the NVT ensemble using a single Nosé-Hoover thermostat set to 300 K (frequency 1800 cm 1), a fictitious electronic mass of 600 a.u., and a time step of 0.121 fs. The boxes contained uranyl and and a total of 42 ammonia molecules, affording a density of 0.71. The system has two positive charges, neutralised by a uniform background charge. In order to maintain the time step, hydrogen was substituted with deuterium. Long-range electrostatic interactions were treated with the Ewald method. No electro-static decoupling between replicated cells was included. Constrained CPMD simulations were performed along a predefined reaction coordinate  (a single U-N bond distance r), starting from the respective mean values for the five-coordinate minumum in gas and solution (as obtained from the unconstrained simulations. Changes in the Helmholtz free energes were evaluated by pointwise thermodynamic integration 13 of the mean constraint force f along this coordinate via      A ab =  a b f()d (1). Electronic Supplementary Material (ESI) for Dalton Transactions. This journal is

Crystal structure of [UO2(NH3)5]NO3·NH3

“…Br 2 ÁNH 3 , U-O distances in the range 1.768 (2) to 1.771 (3) Å were reported (Woidy et al, 2012(Woidy et al, , 2015b; these are shortened by ca 0.1 Å compared to the uranyl ion presented here.…”

[UO2(NH3)5]Br2·NH3: synthesis, crystal structure, and speciation in liquid ammonia solution by first-principles molecular dynamics simulations

“…63) isotypic to the previously reported [UO 2 (NH 3 ) 5 ]Cl 2 •NH 3 . 2 The uranium atom occupies the 4c position, and the oxygen atom O1 the 8f position forming with its symmetry equivalent the uranyl cation. The [UO 2 ] 2+ cation is coordinated by five ammine ligands (N1, N2 and N3 and their symmetry equivalents).…”

“…These hydrogen bond parameters are comparable to the ones previously reported. 2 The unit cell of the title compound [UO 2 (NH 3 ) 5 ]Br 2 •NH 3 is shown in Fig. 2, crystallographic details are available from Table 1.…”

“…We have explored its use for preparative purposes and have added a number of uranium-ammonia compounds to the growing portfolio of uranyl(VI) and uranium(IV) complexes. 2,3 We now report on a new compound that was isolated during our speciation studies, [UO 2 (NH 3 ) 5 ]Br 2 •NH 3 .…”

The reactions of TiCl3, and of UF4with TiCl3in liquid ammonia: unusual coordination spheres in [Ti(NH3)8]Cl3·6NH3and [UF(NH3)8]Cl3·3.5NH3

“…20 For the [UO 2 F 2 (NH 3 ) 3 ] 2 Á2NH 3 compound longer U-F-distances ranging from 2.217(2) to 2.241(2) Å have been observed. 46 So, the uranium(IV) cation seems to exert a strong pull towards the F À anion. Selected atomic distances and angles of the crystal structure are available from Table S4 (ESI †) and the caption of Fig.…”