We report on an investigation of the low-temperature structural, thermal, and magnetic properties of the binary trifluoride VF3 by temperature-dependent magnetization, heat capacity, electron paramagnetic resonance, and synchrotron powder and neutron powder diffraction measurements. At room temperature the crystal structure of VF3 features V3+ spin S = 1 regular triangular layers. At similar to 120 K VF3 undergoes a structural phase transition, and at similar to 18 K it undergoes an antiferromagnetic phase transition. The structural phase transition involves a minute orthorhombic distortion of the regular octahedral fluorine coordination shell of the trivalent V cations, effecting a distortion to the monoclinic crystal system. The magnetic phase transition generates a weak ferromagnet with V magnetic moments essentially confined to the trigonal planes of the room temperature structure described in the space group R - 3c. The ordered magnetic moments of the V3+ cations amount to approximate to 1 & micro;B and is thus distinctly reduced from the spin-only magnetic moment of 2 & micro;B. This finding and the weak ferromagnetic moment are discussed in view of the low-symmetry structure and spin-orbit effects on the 3T1 cubic ground term of the V3+ d2 system.

We report on an investigation of the low-temperature structural, thermal, and magnetic properties of the binary trifluoride VF 3 by temperature-dependent magnetization, heat capacity, electron paramagnetic resonance, and synchrotron powder and neutron powder diffraction measurements. At room temperature the crystal structure of VF 3 features V 3 + spin S = 1 regular triangular layers. At ∼ 120 K VF 3 undergoes a structural phase transition, and at ∼ 18 K it undergoes an antiferromagnetic phase transition. The structural phase transition involves a minute orthorhombic distortion of the regular octahedral fluorine coordination shell of the trivalent V cations, effecting a distortion to the monoclinic crystal system. The magnetic phase transition generates a weak ferromagnet with V magnetic moments essentially confined to the trigonal planes of the room temperature structure described in the space group R − 3 c . The ordered magnetic moments of the V 3 + cations amount to ≈ 1 μ B and is thus distinctly reduced from the spin-only magnetic moment of 2 μ B . This finding and the weak ferromagnetic moment are discussed in view of the low-symmetry structure and spin-orbit effects on the 3 T 1 cubic ground term of the V 3 + d 2 system.

UCl4, UBr4, UBr5, or UO2Cl2 reacted with excess liquid ammonia - in adventitious presence of moisture and/or air - and formed some peculiar uranium compounds of which we present the crystal structures. [(NH3)7(N3)U(mu-O)U(NH3)8]Cl5 & sdot; 7NH3 contains a dinuclear mu-O-bridged uranium(IV) cation, [{(NH3)4UO2}2(mu-O)]Cl2 & sdot; 4NH3 features a dinuclear mu-O-bridged uranyl(VI) cation, while the compounds [(U(VI)O2)2(U(V)O2)2(mu 3-O)2(NH3)12]Br2 & sdot; 6NH3 and [(U(VI)O2)4(U(V)O2)4(mu 3-O)4(NH3)22]Br4 & sdot; 16NH3 are mixed-valent containing uranyl(V)-uranyl(VI) units. For these tetra- and octanuclear complex cations we observed that the O atoms of the uranyl(V) units can be mu 2- and even mu 3-bridging to uranyl(VI) units, while the O atoms of the latter are acting as terminal ligands only. [(NH3)8U(mu-N)U(NH3)5(mu-N)UO2(NH3)4]Br6 & sdot; 18NH3 presents the first example of a compound where the isoelectronic species UO22+ and UN2 formed a complex with the NUN unit bridging to the U atom of the uranyl(VI) cation. As it is can be difficult to distinguish between N and O atoms with X-ray diffraction, quantum-chemical calculations at the DFT-PBE0/TZVP level of theory were carried out which unequivocally confirmed the atom assignments in the crystal structures. The chemical bonding in the complex cations was studied using intrinsic bonding orbitals and allowed for an additional discrimination of the U(V) and U(VI) atoms in the mixed-valent compounds. We present the syntheses and crystal structures of several adventitious hydrolysis products of UCl4, UBr4, UBr5, and UO2Cl2. We obtained compounds containing dinuclear mu-O-bridged uranium(IV) cations, mixed-valent uranyl(V)-uranyl(VI) tetra- and octanuclear complex cations, and also a compound where the isoelectronic species UO22+ and UN2 formed a complex. image

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This article presents an overview of recent advancements in the field of uranium chemistry, paying special attention to the preparation of starting materials and to the chemistry of uranium halides in liquid ammonia. Where suitable, insights into the chemistry of thorium are also presented. Herein, we report upon the crystal structures of several ammine complexes as well as their deprotonation products. Specific examples of hydrolysis products in liquid ammonia are showcased. Additionally, advancements in the preparation of uranium cyanides are presented.

Pentaammine dioxide uranium(V) nitrate ammonia (1/1), [UO2(NH3)5]NO3·NH3, was obtained in the form of yellow crystals from the reaction of caesium uranyl nitrate, Cs[UO2(NO3)3], and uranium tetrafluoride, UF4, in dry liquid ammonia. The [UO2]+ cation is coordinated by five ammine ligands. The resulting [UO2(NH3)5] coordination polyhedron is best described as a pentagonal bipyramid with the O atoms forming the apices. In the crystal, numerous N—H...N and N—H...O hydrogen bonds are present between the cation, anion and solvent molecules, leading to a three-dimensional network.

Our attempts to synthesize the hitherto unknown binary copper(I) fluoride have led to first successes and a serendipitious result: By conproportionation of elemental copper and copper(II) fluoride in anhydrous liquid ammonia, two copper(I) fluorides were obtained as simple NH3 complexes. One of them presents an example of ligand-unsupported "cuprophilic" interactions in an infinite [Cu2 (NH3 )4 ](2+) chain with alternating Cu-Cu distances. We discovered that both copper(I) fluorides can easily be converted into Cu3 N at room temperature, just by applying a vacuum. Additionally, we investigated the formation mechanism of the classical synthesis route of Cu3 N that starts with CuF2 and flowing NH3 in the temperature range between ambient and 290 °C by means of thermal analysis and in situ neutron diffraction. The reaction proceeds at elevated temperatures through the formation of a blue and amorphous ammoniate Cu(NH3 )2 F2 , the reformation of CuF2 , and finally the redox reaction to form Cu3 N.

TiCl3 and NH3 form octaammine titanium(III) chloride ammonia (1/6), [Ti(NH3)8]Cl3·6NH3, which is the first structurally characterized octaammine complex of a transition metal. An excess of TiCl3 reacts with UF4 in liquid NH3 and forms octaammine fluorido uranium(IV) chloride ammonia (1/3.5), [UF(NH3)8]Cl3·3.5NH3. It shows a distorted threefold-capped trigonal-prismatic coordination sphere around U(IV).

TiCl3 and NH3 form octaammine titanium(III) chloride ammonia (1/6), [Ti(NH3)(8)]Cl-3 center dot 6NH(3), which is the first structurally characterized octaammine complex of a transition metal. An excess of TiCl3 reacts with UF4 in liquid NH3 and forms octaammine fluorido uranium(IV) chloride ammonia (1/3.5), [UF(NH3)(8)]Cl-3 center dot 3.5NH(3). It shows a distorted threefold-capped trigonal-prismatic coordination sphere around U(IV).

[UO2(NH3)5]Cl2 ∙ NH3 with a = 13.2499(2), b = 10.5536(1), c = 8.9126(1) Å, V = 1246.29(3) Å 3 and Z = 4 at 123 K. The UO2 2+ 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 15

Vanandium trifluoride reacts with dry liquid ammonia under the formation of lilac plate-shaped crystals of mer-triammine trifluorido vanadium(III) (1), mer[VF3(NH3)3]. Single-crystal X-ray analysis was carried out at low temperature to elucidate the structure. The compound crystallizes in the monoclinic space group P21/c with a = 5.7284(4), b = 9.2033(5), c = 10.5271(6) Å, β = 91.795(6)°, and V = 554.72(6) Å3 at 123 K with Z = 4. The discrete [VF3(NH3)3] molecules are interconnected by hydrogen bonds.

Pentaammine dioxido uranium(VI) dibromide ammonia (1/1), [UO2(NH3)5]Br2·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]Cl2·NH3 with a = 13.2499(2), b = 10.5536(1), c = 8.9126(1) Å, V = 1246.29(3) Å(3) and Z = 4 at 123 K. The UO2(2+) 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.

Iridium is one of the most important platinum group metals and is used in several alloys and in the automotive industry for the purposes of making catalysts. Therefore, its recycling is a very actual challenge for researchers working in the field of urban mining. Reactions of various tetrafluorobromates MBrF4 (M = K, Rb, Cs) and M'(BrF4) 2 (M' = Ba) with Ir metal have been investigated. Compositions of the obtained products have been determined, corresponding reaction schemes have been suggested, and proper conditions for the reactions have been established. (C) 2014 Published by Elsevier B.V.

The reaction of K2Th(NO3)(6) and UF4 with liquid ammonia as a solvent leads on air to planar colorless crystals of ditriakontaammine hexadeca-mu-fluorido tetra-mu(3)-oxido tetra-mu(4)-oxido decathorium(IV) octanitrate ammonia (1/19.6), [Th10F16O8(NH3)(32)](NO3)(8)center dot 19.6 NH3 (1). The compound crystallizes in the tetragonal space group P (4) over bar2(1c) (no. 114) with a = 18.4167(2), c = 14.7920(4) angstrom, and V = 5017.1(2) angstrom(3) at 123 K with Z = 2. The crystal structure shows the presence of a decanuclear thorium core [Th10O4](32+) similar to an "inverse" P4O10 or like 1,3,5,7-tetramethyladamantane. Such a complex seems to be the largest thorium complex reported so far - a finding that is of great importance for the knowledge of actinoid speciation in solutions.

We report the synthesis and crystal structure of the monohydrate of hexaammine copper(II) difluoride, [Cu(NH 3 ) 6 ]F 2 · H 2 O, which was synthesized from CuF 2 · 2 H 2 O in liquid ammonia. The compound crystallizes in the chiral space group P3 2 21 (no. 154) as traffic-blue, plate-shaped crystals with a = 6.738(1), c = 18.210(6) Å, V = 715.9(3) Å3 at 150 K with Z = 3. It contains the rare [F(H 2 O)F 2- anion bound by strong O-H···F hydrogen bonding.

CsBrF4 (I) and CsBr2F7 (II) are prepared by the reaction of stoichiometric amounts of CsF and BrF3 (previously published method).

We report on the synthesis and crystal structure of the octaammine calcium(II) halides [Ca(NH3)8]Br2, and [Ca(NH3)8]I2, which were synthesized by the reaction of the respective calcium( II) halides with dry liquid ammonia. The compounds form colorless crystals which crystallize isotypically at 123 K with Z = 4 in the orthorhombic space group Pnma with a = 12:0478(3), b = 7:4406(2), c = 15:7216(4) Å, V = 1409:33(6) Å3 for the bromide, and a = 12:1113(4), b = 7:7706(3), c = 16:7145(6) Å, V = 1573:0(1) Å3 for the iodide. Instead of the expected tetragonal antiprism for the eightfold-coordinated Ca2+ ions, we observed a coordination polyhedron best described as a twofold capped trigonal prism. After evaporation of the liquid ammonia and warming of [Ca(NH3)8]I2 to room temperature, [Cu(NH3)6]I2 was obtained as a colorless powder. The hexaammine calcium(II) iodide crystallizes isotypically to [Mn(NH3)6]I2 (CaF2 type) in the cubic space group Fm3̅m with a = 11:18580(6) Å, V = 1399:59(1) Å3, Z = 4 at 293 K

Dicaesium hexa-nitratothorate(IV), Cs2[Th(NO3)6], was synthesized in the form of colourless crystals by reaction of thorium nitrate and caesium nitrate in aqueous solution. The Th atom is located on an inversion centre and is coordinated by six chelating nitrate anions. The resulting ThO12 coordination polyhedron is best described as a slightly distorted icosa-hedron. The Cs atom also has a coordination number of 12, but its coordination polyhedron is considerably more distorted. The crystal packing can be derived from an hexa-gonal dense packing (hcp) of idealized spherical CsO12 and ThO12 units. The CsO12 units form a distorted hcp arrangement and half of the octa-hedral sites are occupied by the ThO12 units.