New quaternary carbon and nitrogen stabilized polyborides: REB15.5CN (RE: Sc, Y, Ho, Er, Tm, Lu), crystal structure and compound formation

A new family of quaternary carbon and nitrogen containing Rare Earth (RE: Sc, Y, Ho, Er, Tm and Lu) borides: REB_15.5CN, has been synthesized and structurally characterized by powder X-ray diffraction data. They are all isotypic with Sc_1−xB_15.5CN whose structure was solved based on single-crystal X-ray data and HRTEM investigations. The structure refinement converged at a R(F²) value of 0.044 for 364 reflections. The new structure type of Sc_1−xB_15.5CN is composed of a three-dimensional network based on interconnected slabs of boron (B₁₂)^ico icosahedra and (B₆)^oct octahedra. A linear [CBC] chain and nitrogen tightly bridges icosahedra. Sc partially occupies voids in the sheets of boron octahedra. It crystallizes with the trigonal space group P³m1, with Z=2. Lattice parameters (nm) are as follows: for RE: Sc, a,b=0.5568(4), c=1.0756(2); Y, a,b=0.55919(6), c=1.0873(2); Ho, a,b=0.55883(7), c=1.0878(6); Er, a,b=0.55889(5), c=1.0880(6); Tm, a,b=0.5580(1), c=1.0850(6); Lu, a,b=0.55771(9), c=1.0839(4). Magnetic characterization of ErB₁₇C_1.3N_0.6 has been performed.     

Structure of palladium quinoline-8-selenolate Pd(C9H6NSe)2

The molecular and crystal structure of palladium quinoline-8-selenolate Pd(C₉H₆NSe)₂ has been determined by X-ray structural analysis. The structures of the five-membered metallocycles of palladium 8-hydroxy-, 8-mercapto-, and 8-hydroselenoquinolinates of one type are compared. __________ Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 3, pp. 396–402, March, 2006.     

Crystal Structures and Magnetic Properties of the Two Misfit Layer Compounds: [SrGd0.5S1.5]1.16 NbS2 and [Sr(Fe,Nb)0.5S1.5]1.13 NbS2

Crystal structures of two new misfit compounds, [SrGd_0.5S_1.5]_1.16NbS₂ and [Sr(Fe,Nb)_0.5S_1.5]_1.13NbS₂, were determined through the composite approach, i.e., by refining each subpart (Q, H-parts, and the common part) of these composite materials, separately. The Q-part is a three-atom-thick layer, with the NaCl-type structure, where external SrS planes enclose the inner GdS or (Fe,Nb)S plane; the structural difference between these two compounds lies in the central layer within the Q-part: Gd and S atoms are in special positions (octahedral coordination), while Fe and S atoms are statistically distributed on split (×4) positions (tetrahedral coordination) around a central unique site (=special position occupied by Nb). The H-part is a sandwich of sulfur planes enclosing the inner Nb plane as observed for the structure of the binary compound NbS₂ itself. The Sr-Gd derivative shows a paramagnetic behavior in the whole studied temperature range (2-300 K). On the other hand, antiferromagnetic interactions occur in the Sr-Fe derivative; the complex magnetic behavior of this compound is related to the statistical distribution of Fe atoms which leads to frustration of the magnetic interactions. At room temperature, experimental values obtained from Mössbauer spectrum correspond to Fe³⁺ in tetrahedral sulfur environment: isomer shift δ=0.32 mm s⁻¹, and quadrupole splitting ΔE=0.48 mm s⁻¹.     

Direct calculation of ionization potentials of closed-shell atoms and molecules

Vertical ionization potentials, electron affinities and information about quasi-particles can be obtained by using the technique of the single-particle propagator. The expansion of the self-energy part up to third order perturbation theory can be evaluated numerically, but does not lead, in most cases, to satisfying results. A theoretical and numerical analysis of the diagrammatic expansion of the self-energy part requires the introduction of a renormalized interaction and renormalized hole and particle lines.     

Crystal and molecular structure of nitraminotetrazole and nitramino-1,2,4-triazole. IV. 5-nitraminotetrazole sodium salt sesquihydrate

The structure of 5-nitraminotetrazole sodium salt sesquihydrate was determined by X-ray diffraction. The crystals are monoclinic, space group P2₁/c;a = 3.551(1) Å, b = 21.834(4) Å, c = 9.075(2) Å; = 110.68(3)°; V = 658.3(2) ų; Z = 4; _calc = 1.807 g/cm³. The anion is planar and has an intramolecular hydrogen bond. The negative charge of the anion is localized on one of the oxygens of the nitro group. The sodium cation (c.n.6) is coordinated by three oxygen atoms of different anions and three oxygens of crystallization water. One of the crystallization water molecules is disordered in the unit cell. The anions are hydrogen-bonded with each other and with crystallization water molecules.Original Russian Text Copyright © 2004 by A. M. Astakhov, A. D. Vasiliev, M. S. Molokeev, L. A. Kruglyakova, A. M. Sirotinin, and R. S. StepanovTranslated from Zhurnal Strukturnoi Khimii, Vol. 45, No. 3, pp. 562–565, May–June 2004.     

Organometallic gold(III) and gold(I) complexes as catalysts for the 1,3-dipolar cycloaddition to nitrones: synthesis of novel gold-nitrone derivatives

Gold(III) and gold(I) anionic salts mediate the 1,3-dipolar cycloaddition of N-benzyl-C(2-pyridyl)nitrone (2-PyBN) (1) and methyl acrylate (2) (gold 5-10 mol% with respect to the nitrone) decreasing the reaction time and favouring the formation of the exo (cis) isomer. The best catalyst found was Na[AuCl₄] (7) able to perform the addition reaction in 56 h (instead of the 96 h required for the control experiment) and giving an endo/exo relation between isomers of 44/56 (as opposed to 73/27, blank reaction). The catalytic activity of several organometallic gold complexes with the radicals pentafluorophenyl (C₆F₅) or mesityl (2,4,6-(CH₃)₃C₆H₂) has been also investigated. In some cases the activity is very similar to that obtained with inorganic salts. With the aim of identifying possible metallic intermediates in the cycloaddition reaction, novel gold(III) and gold(I) nitrone derivatives such as [Au(C₆F₅)Cl₂(2-PyBN)] (21), [Au(C₆F₅)₂Cl(2-PyBN)] (22) and [Au(C₆F₅)(2-PyBN)] (23) have been prepared and characterized. The reaction between [AuCl₃(tht)] and 2-PyBN unexpectedly affords the ionic compound [2-PyBN-H][AuCl₄] (5) which also displays catalytic activity and moderate regioselectivity and whose crystal structure has been confirmed by X-ray studies.     

Reaction of cyclopentadienyllutetium anthracenide with azobenzene. Synthesis and molecular and crystal structure of the binuclear complex [C5H5(THF)Lu(μ−η2:η2−PhN—NPh)]2(THF)2 and its dynamic behavior in solution

The reaction of the cyclopentadienyllutetium anthracenide, C₅H₅Lu(C₁₄H₁₀)²⁻(THF)₂ (1), with azobenzene yielded the [C₅H₅(THF)Lu(μ−η²:η²−PhN—NPh)]₂(THF)₂ (2) binuclear complex. The structure of the reaction product was established by X-ray structural analysis. The dynamic behavior of complex2 in a THF-d₈ solution was studied by¹H NMR spectroscopy in the temperature range of 265–330 K. Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 9, pp. 1667–1671, September, 1997.     

Reaction of Tetracopper(I)-Phosphonitocavitand with PhSeSiMe3: Synthesis and Structure of a Polyanionic Cluster [pyH]6[(CuCl)9(μ3-SePh)5(μ4-SePh)]

Treatment of tetracopper(I)-phosphonitocavitand [1·Cu₄(μ-Cl)₄(μ₄-Cl)] (2) (1 = tetraphosphonitocavitand [rccc-2,8,14,20-tetrakis-(iso-butyl)-phosphonitocavitand (C₄₄H₄₈O₈P₄Ph₄)]) with PhSeSiMe₃ in THF at low temperature afforded a novel polyanionic cluster [pyH]₆[(CuCl)₉(μ₃-SePh)₅(μ₄-SePh)] (4) as a major product along with a new tetracopper(I)-phosphonitocavitand (3) with a centered μ₃-Cl. Molecular structure of anionic cluster in 4 consists of six PhSe⁻ bridging ligands containing five μ₃-SePh and one exceptional μ₄-SePh bridging nine copper atoms, of which eight copper atoms have trigonal coordination geometry and the other has distorted tetrahedral geometry. Dedicated to Professor Han-Qin Liu on the occasion of his 70th birthday.     

Reactions of 2-arsa- and 2-stiba-1,3-dionato lithium complexes with group 4-7 metal halides

The reactions of a range of 2-arsa- and 2-stiba-1,3-dionato lithium complexes with group 4-7 metals have been investigated. These have given rise to several complexes in which an arsadionate acts as a chelating ligand; [V{η²-O,O-OC(Bu^t)AsC(Bu^t)O}₃], [M{η²-O,O-OC(Bu^t)AsC(Bu^t)O}₂(DME)], M=Cr or Mn; or as an η¹-As-diacylarsenide, [MnBr(CO)₄{As[C(O)Bu^t]₂Li(DME)}]₂. In addition, reactions of lithium arsadionates with TaCl₅ have led to metal mediated arsadionate decomposition reactions and arsadionate oxidative coupling reactions to give the known arsaalkyne tetramer, As₄C₄Bu^t₄, and the new tetraacyldiarsane, [{As[C(O)Mes]₂}₂] Mes=mesityl, respectively. The treatment of several lithium arsadionates with [MoBr₂(CO)₂(PPh₃)₂] has also initiated arsadionate decomposition reactions and the formation of the metal carboxylate complexes, [MoBr(CO)₂{η²-O₂C(R)}(PPh₃)₂] R=Bu^t, Ph, Mes. The X-ray crystal structures of six of the prepared complexes are discussed.     

Strukturen aus AIB2− und BaAl4−analogen Einheiten. I Die Verbindungen Sr4Pd5P5 und Sr2Pd3P3

Structures with AIB₂? and BaAl₄?type Units. I The Compounds Sr₄Pd₅P₅ and Sr₂Pd₃P₃ Sr₄Pd₅P₅ (Cmcm, a = 4.177(1) Å, b = 31.377(5) Å, c = 8.581(2) Å, Z = 4) und Sr₂ Pd₃P₃(Pmmm, a = 4.199(1) Å, b = 4.212(1) Å, c = 34.227(4) Å, Z = 4) have been prepared by heating the elements. Both structures contain exclusively units characteristic for the AIB_2? and BaAl₄?type. The ratio between isolated P-atoms and P₂?pairs is interpreted with an ionic splitting of the formulas.