A Revised Structure Model for the UCl6 Structure Type,Novel Modifications of UCl6 and UBr5, and a Comment on the Modifications of Protactinium Pentabromides

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 Å). 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) Å). This room temperature modification, called rt-UCl₆, crystallizes in the trigonal space group P m1, No. 164, hP21, with a=10.907(2), c=5.9883(12) Å, V=616.9(2) ų, 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-UCl_6. 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) Å, β=96.68(2)°, V=1203.6(5) ų, 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 , No. 2, aP36, with a=10.4021(6), b=11.1620(6), c=12.2942(7) Å, α=68.3340(10)°, β=69.6410(10)° and γ=89.5290(10)°, V=1231.84(12) ų, Z=3 at T=100 K. In this structure the UBr₅ units are dimerized to U₂Br₁₀ 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.     

Synthesis,Crystal Structures,Thermal and Magnetic Properties of New Selenocyanato Coordination Polymers with Pyrazine as Co‐Ligand

Reaction of iron(II), cobalt(II) and nickel(II) selenocyanate with pyrazine in water at room temperature leads to the formation of the isotypic new ligand‐rich 1:2 (1:2 = ratio between metal and co‐ligand) compounds [M(NCSe)₂(pyrazine)₂]_n (M = Fe ( 1 ), Co ( 2 ), Ni ( 3 )). The crystal structure of 2 was determined by X‐ray single crystal analysis and those of 1 and 3 were refined from X‐ray powder data with the Rietveld method. In their crystal structure the metal(II) cations are coordinated by four pyrazine co‐ligands, which connect them into layers, and two terminally N‐bonded selenocyanato anions in a distorted octahedral arrangement. The terminal coordination mode of the selenocyanato anions was further emphasized by IR spectroscopic investigations. On heating, all compounds decompose in a single heating step without the formation of ligand‐deficient intermediates like previously reported for related thiocyanato compounds. Magnetic measurements of compound 1 show a long‐range antiferromagnetic ordering with an ordering temperature of T_N = 6.7 K, which must be mediated by the aromatic π‐system of the pyrazine ligand, whereas 2 and 3 show only Curie–Weiss behavior with antiferromagnetic exchange interactions.     

Studies On Rare-Earth Complexes with Crown Ethers. Part XXV. Synthesis,characterization, and structure of the complexes of lanthanide nitrates with 13-crown-4

The lanthanide nitrate complexes with 13-crown-4(13-C-4) have been prepared in AcOEt. These new complexes with the general formula Ln(NO₃)₃.(13-c-4) (Ln = La–Nd, Sm–Lu) have been characterized by means of elemental analysis, IR and ¹H-NMR spectra, conductivity measurements, and TG-DTA techniques. The crystal and molecular structure of Nd(No₃)₃. (13-c-4) has been determined by single crystal X-ray diffraction. It crystallizes in the monoclinic space group P2₁/a with Z = 8. Lattice parameters are a = 15.393(1), b = 12.578(1), c = 19.279(2) Å, β = 113.05(1)°, V = 3435 ų, D_c = 2.01 g cm^?3, μ = 31.0 cm^?1 (Mok₂), F(000) = 2056. The structure was solved by Patterson and Fourier techniques and refined by least-squares to a final conventional R value of 0.032 for 5218 independent reflections with I ? 3σ(I). There are two independent Nd(No₃)₃ · (13-C-4) monomers in one asymmetrical unit. The coordination numbers are ten in these two independent monomers.     

Synthesis and Spectroscopic Characterization of the Benzaldehyde Schiff Base of S‐Allyldithiocarbazate and its Copper(II) Complex and the X‐ray Crystal Structure of Bis[S‐allyl‐β‐N‐benzylidene)dithiocarbazato]Copper(II)

S‐allyl‐β‐N‐(benzylidene)dithiocarbazate (sabdtc, 1 ), prepared from hydrazine hydrate, carbon disulfide, allyl bromide and benzaldehyde, reacts with copper(II) nitrate in ethanol solution to form the complex Cu(sabdtc)₂ ( 2 ). 1 function as a single negatively charged bidentate chelating ligand and coordinates via the azomethine nitrogen atom and thioenolate sulfur atom to the metal ion. 1 and 2 were characterized by elemental analyses, ¹H NMR, ¹³C NMR, UV/Vis, IR, and mass spectra. Spectroscopic evidences suggest a four‐coordinate distorted square planar structure for 2 . The molecular and crystal structure of 2 was determined by single crystal X‐ray analysis. Crystallographic data for 2 at 291(2) K: space group C2/c, a = 20.340(3), b = 15.503(3), c = 7.659(1) Å, β = 95.96(2)°, Z = 4, R₁ = 0.044 and wR2 = 0.0689.     

Structure and Properties of EuZnGa

New ternary gallide EuZnGa was synthesized by reaction of the elements in a sealed tantalum tube at 1320 K and subsequent annealing at 970 K for seven days. EuZnGa was investigated by X‐ray diffraction on both powders and single crystals. Its structure was refined from single crystal diffractometer data: KHg₂ type, space group Imma, a = 461.7(2), b = 761.4(3), c = 777.0(3) pm, R = 0.041 for 486 structure factors and 13 variables. The zinc and gallium atoms statistically occupy the mercury position of the KHg₂ type of structure. No long‐range ordering between the zinc and gallium atoms could be detected from the X‐ray data. Magnetic susceptibility measurements show Curie‐Weiss behavior above 50 K with a magnetic moment of μ_exp = 7.86(5) μ_B/Eu and θ = 17(2) K, suggesting divalent europium. Low‐field, low‐temperature susceptibility measurements indicate cluster glass behavior (mictomagnetism) with a freezing temperature of 24(2) K. Magnetization measurements show a magnetic moment of 4.9(1) μ_B/Eu at 2 K and a magnetic flux density of 5.5 T. Electrical resistivity data indicate metallic behavior. ¹⁵¹Eu Mössbauer spectroscopic measurements show onset of magnetic hyperfine splitting at ≤ 17.0 K. Down to the temperature of 4.2 K the spectra reflect magnetic relaxation effects suggesting the presence of a substantial extent of disordering. This observation is consistent with the cluster glass behavior as evident from the magnetic susceptibility data and may be a consequence of the presence of multiple local Eu sites as expected from the statistical Zn and Ga distribution over the corresponding sites in the KHg₂ structure.     

K13CoSn17–x (x = 0.1): A New Ternary Phase Containing ­Cobalt Centered [Sn9] Cluster Synthesized via High‐Temperature Reaction

A new ternary potassium cobalt stannide, K₁₃CoSn_17–x (x = 0.1), was obtained by reacting the mixture of the corresponding pure elements at high temperature, and structurally characterized by single‐crystal X‐ray diffraction study. K₁₃CoSn_17–x (x = 0.1) crystallizes in the orthorhombic space group Pbca (No. 61) with a = 26.2799(7) Å, b = 24.1541(6) Å, c = 29.8839(6) Å, V = 18969.3(8) ų, and Z = 16. Its structure contains isolated [CoSn₉] monocapped square antiprism and [Sn₄] tetrahedron in the ratio 1:2, forming a hierarchical variant of Laves phase MgZn₂. The structural relation between the title compound with MgZn₂ as well as other binary stannides is also discussed.     

Synthesis,Crystal Structure,and Characterization of Two Novel Five‐coordinate Zinc(II) Complexes with the Tripod Ligand Tris(N‐methylbenzimidazol‐2‐yl‐methyl)amine and α,β‐unsaturated Carboxylates

Two novel five‐coordinate zinc(II) complexes with the tripod ligand tris(N‐methylbenzimidazol‐2‐ylmethyl)amine (Mentb) and two different α,β‐unsaturated carboxylates, with the composition [Zn(Mentb)(acrylate)] (ClO₄)·DMF·1.5CH₃OH ( 1 ) and [Zn(Mentb)(cinnamate)](ClO₄)·2DMF·0.5CH₃OH ( 2 ), were synthesized and characterized by means of elemental analyses, electrical conductivity measurements, IR, UV, and ¹H NMR spectra. The crystal structure of two complexes have been determined by a single‐crystal X‐ray diffraction method, and show that the Zn^II atom is bonded to a Mentb ligand and a α,β‐unsaturated carboxylate molecule through four N atoms and one O atom, resulting in a distorted trigonal‐bipyramidal coordination [τ( 1 ) = 0.853, τ( 2 ) = 0.855], with approximate C₃ symmetry.     

Synthesis and structure of ammonium tricupric(II)-octadecatungsto-diantimonate(III)

This paper reports the synthesis, properties and structure of (NH₄)₁₂, [Cu₃(H₂O)₃(SbW₉O₃₃)₂]. 11H₂O. The compound was prepared by the depolymerization reaction of (NH₄)₁₈[(NH₄)Sb₉W₂₁O₈₆n-H₂O, which was proposed firstly as a method of preparing new heteropoly tungstoantimonate(III). Its properties were characterized by IR, Raman, UV-VS spectra, TG-DTA thermal analysis, and X-ray single crystal analysis. The crystal is orthorhombic, with space group D¹⁶_2b-Pnma. The crystal data are: a = 15.423(4), b = 19.307(6), c = 30.275(6)Å, V = 9015.0ų, Z = 4, D_c = 3.881 g/cm³. The structure has been refined by full-matrix least squares method to a final R factor of 0.064 for 2652 reflections collected at room temperature. The heteropoly anion contains two α-B-SbW₉O₃₂ subunits joined by three square-pyramidal CuO₄(OH₂).     

SrIrIn6 – An Intergrowth of SrIrIn4 with Indium Slabs

The indium-rich intermetallic compound SrIrIn₆ was synthesized from the elements in a sealed tantalum ampoule at 1173 K, followed by slow cooling for crystal growth. SrIrIn₆ crystallizes with a new structure type which was characterized by X-ray powder and single crystal diffraction: Pmma, a = 852.34(2), b = 434.54(5), c = 1059.18(6) pm, wR₂ = 0.0178, 884 F² values, and 32 variables. The SrIrIn₆ structure shows two basic building units: (i) Ir@In₉ tricapped trigonal prisms (261–292 pm Ir–In) and (ii) distorted bcc In@In₈ cubes (301 to 329 pm In–In). The strontium cations fill cages within the complex three-dimensional [IrIn₆] network and have coordination number 13 (Sr@In₁₃) in form of a tricapped pentagonal prism. The SrIrIn₆ structure can be described as a simple intergrowth variant of SrIrIn₄ (LaCoAl₄ type) with indium slabs. The crystal chemical similarities with the structures of SrIrIn₄, SrIr₂In₈ and Eu₃Ir₂In₁₅ are discussed.     

Kristallstruktur von Natrium‐Dihydrogencyamelurat‐Tetrahydrat Na[H2(C6N7)O3] · 4 H2O

Crystal Structure of Sodium Dihydrogencyamelurate Tetrahydrate Na[H₂(C₆N₇)O₃] · 4 H₂O Sodium dihydrogencyamelurate‐tetrahydrate Na[H₂(C₆N₇)O₃]·4 H₂O was obtained by neutralisation of an aqueous solution, previously prepared by hydrolysis of the polymer melon with sodium hydroxide. The crystal structure was solved by single‐crystal X‐ray diffraction ( a = 6.6345(13), b = 8.7107(17), c = 11.632(2) Å, α = 68.96(3), β = 87.57(3), γ = 68.24(3)°, V = 579.5(2) ų, Z = 2, R1 = 0.0535, 2095 observed reflections, 230 parameters). Both hydrogen atoms of the dihydrogencyamelurate anion are directly bound to nitrogen atoms of the cyameluric nucleus, thus proving the preference of the keto‐tautomere in salts of cyameluric acid in the solid‐state. The compound forms a layer‐like structure with an extensive hydrogen bonding network.     

Synthesis,spectroscopic characterization,and X-ray crystal structure of tris(trimethylsilyl)cyanurate

Tris(trimethylsilyl)cyanurate, C₁₂H₂₇N₃O₃Si₃ (1), has been synthesized and characterized by elemental analysis, IR, Raman, ¹³C and ²⁹Si NMR, and thermogravimetric methods. The molecular and crystal structure has been determined by single crystal X-ray diffraction. This compound crystallized in space group P6₃/m (176), Z = 2 with a = 11.017(2), b = 11.017(2), c = 9.676(3) Å; α = 90°, β = 90°, γ = 120°. The geometry of the molecule is compared with tris(trimethylsilyl)cyamelurate.     

Crystal structure of indium(III) Schiff base complex

The title compound [In(C₂₂H₃₀N₄O₄)]Cl (I) bis[(N-salicylidene-N′-(2-hydroxyethyl)ethyleneediamine) indium(III) chloride is prepared, and its crystal structure is determined by single crystal X-ray diffraction at room temperature. The complex crystallizes in the monoclinic space group P2₁/n, a = 9.9704(6) ?, b = 24.9554(15) ?, c = 10.5707(6) ?, β = 116.46(2)°, V = 2354.6(2), Z = 4. The X-ray analysis reveals that the In^III ion is surrounded by four nitrogen and two oxygen atoms from two ligands leading to a distorted octahedral geometry. The molecule has the form of tongs at a junction point with the metal. Five membered rings adopt envelope conformation. In the crystal structure, the molecules are linked via N-H...Cl, O-H...O, O-H...Cl, and C-H...Cl intermolecular interactions. The structure is further stabilized by C-H...π (arene) interactions.     

Crystal Structure,Synthesis, and Properties of tri‐Calcium di‐Citrate tetra‐Hydrate [Ca3(C6H5O7)2(H2O)2]·2H2O

From hydrothermal synthesis needle‐shaped crystals of [Ca₃(C₆H₅O₇)₂(H₂O)₂] · 2H₂O were obtained. The crystal structure was determined by single‐crystal X‐ray experiments and confirmed by powder data (P$\bar{1}$ (no. 2) a = 5.9466(4), b = 10.2247(8), c = 16.6496(13) Å, α = 72.213(7)°, β = 79.718(7)°, γ = 89.791(6)°, V = 947.06(13) Å³, Z = 2, R1 = 0.0426, wR2 = 0.1037). The structure was obtained from pseudo merohedrically polysynthetic twinned crystals using a combined data collection approach and refinement processes. The observed three‐dimensional network is dominated by eightfold coordinated Ca²⁺ cations linked by citrate anions and hydrogen bonds between two non‐coordinating crystal water molecules and two coordinating water molecules.     

The reactivities of Mo cluster — A selective substitution reaction of the bridging (dtp) ligand and the crystal structure of {Mo3S4(μ-O2CR)(dtp)3(Py)}

The reaction of trinuclear molybdenum cluster {Mo₃S₄(μ-dtp) (dtp)₃ (H₂O)} 1 [dtp= S₂P(OEt)₂] with RCO₂Na (R?H, CH₃) in the presence of Py gave the black compounds {Mo₃S₄ {μ-O₂ CR) (dtp)₃ (Py)} (2, R?H, 3, R?CH₃). Both compounds are characterized by X-ray crystallography. It is shown that crystals 2 and 3 belong to space group P&1bar; with Z=2 and a=10.519(2), b= 12.121(2), c=15.757(2)Å, α=93.27(1), β=94.63(1), γ = 105.22(1)°, V= 1925 ų for crystal 2, whereas a=9.556 (2), b=14.067(7), c=15.914 (9) Å, α=101.41 (4), β=101.44(4), γ-74.26(3)°, V=1994ų for crystal 3. The final R factors are 0.041 and 0.048 for crystal 2 and 3 respectively. The structure analysis indicates that (O₂CR)^? ligand selectively substitutes the bridging (dtp) ligand. This type of Mo, cluster molecule where structure contains two species of bidentate ligand is for the first time to be obtained by us.     

Assembly and Crystal Structure of a Novel 1—D Coordination Polymer of Copper（Ⅱ）with Thiocyanate and 4—Cyanopyridine

A novel one‐dimensional coordination polymer, Catena‐poly [bis(4‐cyano‐pyridyl) copper(II)‐di‐thiocyanate], ¹_∞ [Cu^II‐(cypy)₂(μ_N.S‐SCN)₂] (cypy = 4‐cyano‐pyridyl), was synthesized in a solution reaction of Cu(NO₃)₂·3H₂O, 4‐cyano‐pyridine and KSCN in mole ratio of 1:2:2 at room temperature. Its crystal structure was determined by single‐crystal X‐ray diffraction. The crystal belongs to monoclinic crystal system, space group P2₁/c with cell parameters a = 1.0719(2), b = 1.8441(4), c =0.9144(2) nm, β = 110.49(3)° and Z = 4. A full‐matrix least‐squares refinement gave R₁ = 0. 0393 and wR₂= 0.0916 for 1554 reflections having 1 >2σ(I). The crystal is thermally stable up to approximately 170 °C.     

Molecular Structure and a Density Functional Theoretical Study on 2‐Nitroimino‐5‐Nitro‐Hexahydro‐1,3,5‐Triazine (NNHT)

2‐Nitroimino‐5‐nitro‐hexahydro‐1,3,5‐triazine (NNHT), was synthesized and its structure was determined by single‐crystal X‐ray diffraction. The crystal is monoclinic, space group P2₁/c with crystal parameters of a = 9.4031(13) Å, b = 8.5891(12) Å, c = 9.0200(13) Å, β = 91.213(2)°, V = 728.33(18) ų, Z = 4, F(000) = 392, D_c = 1.734 g/cm³. The experimental geometry of NNHT was input to Gaussian‐03W program and optimized using DFT‐B3LYP/6‐311++G** method. The IR frequencies and NMR chemical shift were carried out and compared well with those of the experimental. The atomic net charges and the population analysis are discussed. The heat of formation (HOF) for NNHT was evaluated by designing an isodesmic reaction. The detonation velocity (D) and detonation pressure (P) were estimated by using the well known Kamlet‐Jacobs equation, based on the theoretical HOF.     

Die Undecaarsenide A3As11 (A = Rb,Cs) — Synthesen und Kristallstrukturen

Alkaline Metal Arsenides A₃As₁₁ (A = Rb, Cs): Preparation and Crystal Structures Rb₃As₁₁ and Cs₃As₁₁ were synthesized from the elements and the crystal structures of the ordered room temperature form were characterized via single crystal x‐ray studies. In the Zintl phases the As atoms form chiral ufosan‐anions As with As‐As distances ranging from 238 to 248 pm. Like K₃As₁₁ Rb₃As₁₁ crystallizes with the Na₃P₁₁ structure type (orthorhombic, space group Pbcn, a = 1108.2(2), b = 1533.5(3), c = 1060.1(2) pm, Z = 4), whereas the Cs compound (monoclinic, space group C2/c, a = 1324.5(7), b = 1524.5(9), c = 1937.2(11) pm, β = 95.29(1)°, Z = 8) forms a new structure type. The crystallographic relationship between the two structure types and the anion packings in the plastic crystalline high temperature forms are discussed.     

Crystal transition and structure of poly (γ-n-alkyl glutamate)s

The nature of the crystal transition of the α-helical forms of poly (γ-n-alkyl glutamate)s (alkyl = ethyl, propyl, and butyl) is described. The transition is thermally reversible, and its temperature T₂ is much higher than the glasslike transition temperature T₁ associated with the side-chain motion. The main chains undergo large-scale motion (librational about the chain axis and translational along the axis) above T₃ ≈ 200°C. The structure observed below T₂ is anomalously disordered compared with that observed between T₂ and T₃. The crystal structure emerging above T₂ is analyzed for a typical sample of poly(γ-n-propyl L -glutamate). The trigonal unit cell contains three α-helices so that each helix is surrounded by other helices in the same fashion, but the helices are not interrelated by a crystallographic symmetry element. The side chains suffer no particular change at T₂. The main-chain motion gives rise to the T₂ transition by inducing attractive forces between interpenetrating side chains.     

Binary Compounds of Rhodium and Zinc: RhZn,Rh2Zn11, and RhZn13

The title compounds were prepared by reaction of the elements at elevated temperatures in sealed silica tubes. Single crystals of RhZn and RhZn₁₃ were obtained by slow cooling of samples with a high zinc content after dissolving the zinc‐rich matrix in hydrochloric acid. Their crystal structures were determined from single‐crystal X‐ray diffractometer data. RhZn has a CsCl type structure: Pm3m, a = 300.9(1) pm. RhZn₁₃ has a CoZn₁₃ type structure: C2/m, a = 1090.8(2) pm, b = 753.7(2) pm, c = 512.7(1) pm, β = 101.02(2)°. The structure of Rh₂Zn₁₁ is isotypic with Cu₅Zn₈, the γ‐brass structure. It was refined from X‐ray diffractometer powder data: I43m, a = 909.1(1) pm. In these structures all atoms have high coordination numbers. The structure of RhZn₁₃ contains relatively large unoccupied voids. It is suggested that they accommodate nonbonding electrons. Electrical conductivity measurements of Rh₂Zn₁₁ and RhZn₁₃ indicate metallic behavior, however, with an unexpectedly high resistivity for Rh₂Zn₁₁. The expected Pauli paramagnetism of these compounds is overcompensated by the core diamagnetism, suggesting a low density of states at the Fermi level especially for Rh₂Zn₁₁. This correlates with the high electrical resistivity of this compound.     

Kristallstruktur und Phasenumwandlungen von As(CH3)4I

Crystal Structure and Phase Transitions of As(CH₃)₄I The crystal structure of α-As(CH₃)₄I at room temperature was determined using single crystal data: cubic, space group Pa3 , a = 1 198.0(2) pm. Therefore α-As(CH₃)₄I displays a novel crystal structure, which is not comparable to known AB-Typ structures with respect to the arrangement of anions and the baricenters of the complex cations. Differential thermal analysis showed three phase transitions at 103, 175 and 215°C. The lattice parameters of the high temperature phases (temperature dependent Guinier measurements) are: β-As(CH₃)₄I (tetragonal): a = 845.2(2) pm, c = 615.0(2) pm; γ-As(CH₃)₄I (hexagonal): a = 737.7(2) pm, c = 1 082.2(3) pm; and to δ-As(CH₃)₄I (hexagonal): a = 705.8(2) pm, c = 1 147(1) pm. β-and γ-As[(CH₃)]₄I are isotypic to N(CH₃)₄Cl and As(CH₃)₄Br, respectively.