UF 6 and UF 4 in Liquid Ammonia: [UF 7 (NH 3 )] 3− and [UF 4 (NH 3 ) 4 ]

Zeitschrift anorg allge chemie

2012

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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

Section: Resultsmentioning

confidence: 93%

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]

Woidy

Karttunen

Zeitschrift anorg allge chemie

2012

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“…explored [17][18][19][20][21][22][23][24][25][26]. The N-HÁÁÁF hydrogen bonds in compound 1 show donorÁÁÁacceptor (DÁÁÁA) distances between 2.900(2) and 3.135(3) Å , and the DÁÁÁA distances for the N-HÁÁÁO hydrogen bonds are 3.056(2) and 3.262(3) Å ( Table 5).…”

Section: Resultsmentioning

confidence: 99%

Dissolving the insoluble: CdF2 and moist ammonia form cadmium(II) difluoride monohydrate—synthesis and crystal structure of [Cd(NH3)6]F2·H2O

2012

Monatsh Chem

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Hexaamminecadmium(II) fluoride monohydrate (1:1) [Cd(NH 3 ) 6 ]F 2 ÁH 2 O was synthesized from CdF 2 and liquid ammonia in open reaction vessels, so that moisture from the air was in contact with the solvent. The compound crystallizes in the chiral space group P3 1 21-D 4 3 (No. 152) in the form of needle-shaped, colorless crystals with a = 6.8974(1) Å , c = 17.7156(5) Å , V = 729.89(3) Å 3 , and Z = 3.

“…Even strong hydrogen bonds of ammonia molecules, like the one observed in compound 1, rarely have H···F distances shorter than 2.0Å. In previous studies we synthesized the compound [(NH 4 ) 3 (UF 7 NH 3 )]·NH 3 , which shows N-H··· F hydrogen bonds towards ammonia molecules as well as towards ammonium ions, the latter ones in the cation N 2 H 7 + [13], which is also found in the compound N 2 H 7 F, the ammoniate of NH 4 F [12].…”

Section: Preparation and Single-crystal Structure Analysis Of Nh 4 Csmentioning

confidence: 95%

The First Ammoniates of Alkali Metal Fluorides: Cesium Fluoride Ammonia (3/4) [Cs₃F₃(NH₃)₄] and Ammonium Cesium Difluoride [NH₄CsF₂]

Baer

Zeitschrift Für Naturforschung B

2010

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Two new compounds containing cesium fluoride have been obtained as side-products from the reactions of Cs 2 CuF 6 and Cs 2 KDyF 6 with liquid ammonia. Cs 2 CuF 6 reacts with the solvent forming a still unknown blue substance and the colorless ammoniate Cs 3 F 3 (NH 3 ) 4 which crystallizes in the cubic space group I43d (no. 220) with a = 10.273(1)Å and V = 1084.3(2)Å 3 at 123 K with Z = 4. Its crystal structure is isopointal to Y 3 Au 3 Sb 4 and shows an infinite three-dimensional network made up through N-H···F hydrogen bonds. Ammonium cesium difluoride NH 4 CsF 2 crystallizes in the orthorhombic space group Pnma (no. 62) with a = 7.1791(1), b = 4.1244(1), c = 13.6417(2)Å and V = 403.92(1)Å 3 at 123 K with Z = 4. The crystal structure displays two-dimensional infinite layers of the composition 2 ∞ [(NH 4 F 2 ) − ] with embedded Cs + ions. Analogous to the structure of the compound Cs 3 F 3 (NH 3 ) 4 , the structural motif is formed through strong N-H···F hydrogen bonds, which seem to be the guiding force. To the best of our knowledge, the title compounds are the first reported ammoniates of alkali metal fluorides.