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We investigated whether [SiF4(NH3)2] can act as a fluoride-ion acceptor in its reactions with the fluorides AF (A = Li-Cs, Tl, NH4) in anhydrous liquid ammonia (NH3). While LiF and NaF did not react, we obtained the compounds K[SiF5(NH3)], Rb[SiF5(NH3)], and Cs[SiF5(NH3)], as well as [NH4(NH3)2]2[SiF6] and [Tl2(NH3)6][SiF6]·2NH3, from the other starting materials and characterized them by either single-crystal or powder X-ray diffraction. The compound [NH4(NH3)2]2[SiF6] contains the very rarely observed hydrogen-bonded, C2v-symmetric diammine ammonium cation [NH4(NH3)2]+, and the compound [Tl2(NH3)6][SiF6]·2NH3 is an example for an uncommon Tl(I)-Tl(I) interaction. This "thallophilic" interaction was investigated with quantum-chemical methods.

The aqueous chemistry of uranium is dominated by the linear uranyl cation [UO2]2+, yet the isoelectronic nitrogen-based analogue of this ubiquitous cation, molecular [UN2], has so far only been observed in an argon matrix. Here, we present three different complexes of [UN2] obtained by the reaction of the uranium pentahalides UCl5 or UBr5 with anhydrous liquid ammonia. The [UN2] moieties are linear, with the U atoms coordinated by five additional ligands (ammonia, chloride or bromide), resulting in a pentagonal bipyramidal coordination sphere that is also commonly adopted by the uranyl cation [UO2(L)5]2+ (L, ligand). In all three cases, the nitrido ligands are further coordinated through their lone pairs by the Lewis-acidic ligands [U(NH3)8]4+ to form almost linear, trinuclear complex cations. Those were characterized by single-crystal X-ray diffraction, Raman and infrared spectroscopy, 14N/15N isotope studies and quantum chemical calculations, which support the presence of two U≡N triple bonds within the [UN2] moieties. Three crystalline complexes comprising a linear [UN2] moiety that is isoelectronic to the ubiquitous uranyl cation [UO2]2+ have been prepared by reaction of UCl5 or UBr5 with liquid ammonia. Quantum chemical calculations showed that the bonding in the [UN2] moieties is best described with two U≡N triple bonds.

The redetermination of the crystal structure of trigonal UCl6 , which is the eponym for the UCl6 structure type, showed that certain atomic coordinates had been incorrectly reported. This led to noticeably different U-Cl distances within the octahedral UCl6 molecule (2.41 and 2.51 A). Within the revised structure model presented here, which is based on single crystal data as well as quantum chemical calculations, all U-Cl distances are essentially equal within standard uncertainty (2.431(5), 2.437(5), and 2.439(6) A). This room temperature modification, called rt-UCl6 , crystallizes in the trigonal space group P 3 ‾ m1, No. 164, hP21, with a=10.907(2), c=5.9883(12) A, V=616.9(2) A3 , Z=3 at T=253 K. A new low-temperature (lt) modification of UCl6 is also presented that was obtained by cooling a single crystal of rt-UCl6. The phase change occurs between 150 and 175 K. lt-UCl6 crystallizes isotypic to a low-temperature modification of SF6 in the monoclinic crystal system, space group C2/m, No. 12, mS42, with a=17.847(4), b=10.8347(18), c=6.2670(17) A, β=96.68(2)°, V=1203.6(5) A3 , Z=6 at 100 K. The Cl anions form a close-packed structure corresponding to the α-Sm type with uranium atoms in the octahedral voids. During the synthesis of UBr5 a new modification was obtained that crystallizes in the triclinic crystal system, space group P 1 ‾ , No. 2, aP36, with a=10.4021(6), b=11.1620(6), c=12.2942(7) A, α=68.3340(10)°, β=69.6410(10)° and γ=89.5290(10)°, V=1231.84(12) A3 , Z=3 at T=100 K. In this structure the UBr5 units are dimerized to U2 Br10 molecules. The Br anions also form a close-packed structure of the α-Sm type with adjacent uranium atoms in the octahedral voids. Comparisons of the crystal structures of the compounds MX5 (M=Pa, U; X=Cl, Br) show that the crystal structure of monoclinic α-PaBr5 is probably not correct.

We report on results of first-principles electronic structure calculations on disordered $\mathrm{Zn}(\mathrm{Si},\mathrm{Ge},\mathrm{Sn}){\mathrm{N}}_{2}$ alloys. These calculations on substitutional disordered alloys are carried out using the Korringa-Kohn-Rostoker Green function (KKR-GF) method in combination with the coherent potential approximation (CPA) alloy theory. The band gaps and effective masses as well as the disorder-induced finite lifetime of electronic states at the conduction band minimum and valence band maximum are evaluated by analyzing the Bloch spectral functions. Relativistic effects are found to have a small impact and in particular the influence of the spin-orbit coupling is negligible. The alloys with low Si content show band gaps and effective masses which change almost linearly with the composition. Their relatively small effective mass and long lifetime indicate a high charge carrier mobility.

The activation of C–Cl bonds in dichloromethane and chloroform was observed by BeCl2 in the presence of PMe3 and PCy3. This leads to the formation of [Me3PCH2Cl]Cl and [Cy3PCHCl2][BeCl3]. The latter compound is the first example of a tricoordinated beryllium species with nonbulky ligands and proof of the existence and stability of the long-predicted [BeCl3]− ion. In analogy to the isoelectronic BCl3, the trichloroberyllate anion exhibits Lewis acidic behavior toward electron-pair donors and was probed for the electronic and steric influence of the Lewis base. [BeCl3]− can also act as a chloride ion donor or acceptor, leading to the formation of neutral phosphane adducts to BeCl2 and [BeCl4]2–. The existing equilibria between these species were investigated and showed high chloride mobility.

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.

The reaction of uranium tetrachloride with anhydrous liquid hydrogen cyanide yields a turquoise microcrystalline powder of tetrachloridotetraformonitrileuranium(IV), [UCl4(HCN)4]. We determined the crystal structure of this compound by powder neutron diffraction. The compound was further characterized by IR spectroscopy and thermogravimetric analysis as well as by magnetic measurements. The paramagnetic compound crystallizes in the tetragonal space group type I. To the best of our knowledge this compound represents the first structurally elucidated uranium(IV) complex with HCN as a ligand.

In this work we present a facile, lab scale synthesis for thorium tetrahalides ThX4 (X = Cl, Br & I). The reaction between the easily available ThO2 and AlX3 (X = Cl, Br & I) and a subsequent in situ chemical vapour transport (CVT) leads to a product of high purity which is obtained in the form of crystals or large aggregates of crystals. Their identity and purity was evidenced by X-ray powder diffraction and IR spectroscopy. The usage of ThO2 avoids, unlike earlier syntheses, the utilization of scarcely available thorium metal or of other reactants, such as CCl4, leading to impurities. Furthermore, the reaction tolerates even less pure ThO2.

We have reacted β-uranium(V) fluoride with liquid anhydrous hydrogen cyanide and obtained a 1D coordination polymer with the composition ["U" "F" _"5" ("HCN" )_"2" ], (_"∞" ^"1" )"[U" "F" _"4/1" "F" _"2/2" ("HCN" )_"2/1" "]" , revealed by single crystal X-ray structure determination. The reaction system was furthermore studied by means of vibrational and NMR spectroscopy, as well as by quantum chemical calculations. The compound presents the first described polymeric HCN Lewis adduct and the first HCN adduct of a uranium fluoride.

Herein we describe convenient lab scale syntheses of several uranium(iv) halides of high purity by reaction of AlX3 (X = Cl, Br and I) with UO2, which is readily available by reduction of uranyl salts like UO2(NO3)2·6H2O. UCl4, UBr4, and UI4 are obtained in the form of aggregates of large single crystals. Their identities and purity were checked by powder X-ray diffraction, IR spectroscopy and elemental analysis. The syntheses introduced here avoid the need for pure metallic uranium and are based on more readily available starting materials, UO2, which does not even have to be pure, and the respective aluminium halide. Chemical vapor transport (CVT) is applied in situ for purification of the products.

The directed synthesis, spectroscopic properties, and reactivity of bis(trimethylphosphine) beryllium dichloride (1) and bis(diphenylphosphino)propane beryllium dichloride (2) are reported, including the crystal structure of (PMe3)2BeCl2 (1). These four-coordinate beryllium compounds can be alkylated with n-butyllithium (nBuLi) to give three-coordinate (Ph2PC3H6PPh2)BenBu2 (3) and (PMe3)BenBu2 (4). PMe3 can be removed from (PMe3)BenBu2 (4) in vacuo to yield [nBu2Be]2 (5). For the first time, the presence of [nBu2Be]2 as a dimer in solution, which has been postulated for decades, could be observed spectroscopically. This novel, ether-free pathway provides access to beryllium dialkyl compounds that have never been in contact with oxygen-atom-containing reagents or solvents. This “freeness from oxygen” is crucial for semiconductor applications where oxygen is often unwanted and must be avoided at all costs.

The reaction of uranium tetrachloride with anhydrous liquid hydrogen cyanide yields a turquoise microcrystalline powder of tetrachloridotetraformonitrileuranium(iv), [UCl

A new and facile synthesis of O2PtF6 is reported without the demanding synthesis of PtF6 or the use of high pressure fluorination in the presence of oxygen. The O2PtF6 is obtained in form of single crystals by direct Klemm-type fluorination of commercially available PtO2·xH2O in a stream of diluted F2 of atmospheric pressure at a temperature of 275 °C. Its identity and purity was evidenced by powder X-ray diffraction, Raman and infrared spectroscopy. The synthesis allows the preparation of pure dioxygenyl hexafluoridoplatinate(V). The new synthesis of O2PtF6 is deemed more convenient than those that require the extremely reactive PtF6.

We report on the single crystal structure of Na2PtF6, which was synthesized from (NH4)2PtCl6 and NaCl in a flow of 10 % F2 in argon. The light yellow compound crystallizes in the Na2SiF6 structure type with the trigonal space group P321 and the lattice parameters a = 9.2981(2), c = 5.1147(1) A, and V = 382.95(1) A3 at 123 K with Z = 3. Na2PtF6 reacts with liquid ammonia yielding bis triamminesodium hexafluoridoplatinate(IV) [Na(NH3)3]2[PtF6]. It crystallizes in the monoclinic space group C2/c with a = 14.0508(4), b = 8.4894(1), c = 12.8820(4) A, β = 120.495(4)°, and V = 1324.05(6) A3 at 123 K with Z = 4. In contrast to the aqueous system, the solvolysis in NH3 does not lead to the cleavage of the Pt–F bonds, at least not at the temperatures employed in this study.

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).

Herein we describe convenient lab scale syntheses of several uranium(iv) halides of high purity by reaction of AlX

β-Uranium(V) fluoride was reacted with liquid anhydrous hydrogen cyanide to obtain a 1D coordination polymer with the composition 1∞ [UF

The directed synthesis, spectroscopic properties, and reactivity of bis(trimethylphosphine) beryllium dichloride (1) and bis(diphenylphosphino)propane beryllium dichloride (2) are reported, including the crystal structure of (PMe

In view of the separation of U isotopes in nuclear fuel element reprocessing, single crystals of NOUF6 are obtained by direct reaction of NO with UF6 in anhydrous HF (FEP reaction tube, -78 °C) after pumping off excess HF and UF6.

We have synthesized NOUF6 by direct reaction of NO with UF6 in anhydrous HF (aHF). Based on the unit cell volume and powder diffraction data, the compound was previously reported to be isotypic to O2 PtF6 , however, detailed structural data, such as the atom positions and all information that can be derived from those, were unavailable. We have therefore investigated the compound by using single-crystal and powder X-ray diffraction, IR, Raman, NMR, EPR, and photoluminescence spectroscopy, magnetic measurements, as well as chemical analysis, density determination, and quantum chemical calculations.

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).

International audience; A total of 436 young bulls from fifteen Western European breeds, including beef, dairy and local types from five countries, were studied to assess variability in live weight, live weight gain, body measurements and carcass traits. Animals were logged indoors, and fed a diet based on concentrate and straw offered ad libitum from 9 months of age to slaughter at 15 months of age. The weight, body length, height at withers and pelvis width, of the animals were recorded at 9, 12 and 15 months of age. After slaughter, 15 carcass variables were recorded, including carcass weight, EU classification scores, morphological measurements and dissection data. Data were analysed by GLM, regression and principal component analysis procedures. Significant differences were found between breeds for all variables studied, however, the body size measurements and the carcass traits were more useful to discriminate among cattle breeds, than either live weight or daily gain. With respect to the body size and carcass traits the studied breeds could be grouped as: Specialized beef breeds, comprising Piemontese, Asturiana de los Valles, Pirenaica, Limousin, South Devon, Charolais and Aberdeen Angus, all of which were characterized by high muscularity, wide pelvis and medium height and a low to medium level of fatness. Local and dairy breeds, comprising Jersey, Casina, Highland, Holstein and Danish Red, the latter two breeds were tall animals, while the former three breeds were small in size. In general the group was poorly muscled and tended to have a high or medium level of fat. Intermediate group, Avilena, Marchigiana and Simmental: these breeds were characterized by an intermediate muscle conformation and fatness level and were relatively tall. This study provides a detailed assessment or a wide range of variables in the major breeds, and several minor breeds, that are used in breeding programmes across Europe and elsewhere, and will provide information that will be of use to define breeding strategies to meet the demands of the European beef market. (c) 2007 Elsevier B.V. All rights reserved.