Three new lanthanide coordination polymers containing isophthalate and 1,10-phenanthroline

Three lanthanide coordination polymers were prepared by hydrothermal synthesis and characterized by single-crystal X-ray diffraction. [Pr₂(mBDC)₃(phen)(H₂O)]_n·0.5nH₂O (1) (mBDC=isophthalate, phen=1,10-phenanthroline) exhibits two kinds of metal environments (coordination numbers 7 and 8). In complex 1, mBDC ligands adopt the tetradentate (bridging and bridging) coordination mode and connect Pr ions into an undulating layer, and a 3D supramolecular structure is formed via hydrogen bonds between adjacent layers. [Tb₄(mBDC)₆(phen)]_n (2) has three types of metal environments (coordination numbers 6, 7 and 8) and is composed of a 3D network formed by mBDC linking Tb ions via tetradentate (bridging and bridging) and pentadentate (bridging/chelating and bridging) coordination modes. There are two kinds of small quadrilateral channels along the a-axis. [Er₄(mBDC)₆(phen)]_n (3) is isostructural to complex 2.     

Experimental and theoretical study of vibrational spectra and structure of dihalogermylene and dihalostannylene complexes with 1,4-dioxane and triphenylphosphine

Vibrational (Raman and IR) spectra of the 1:1 complexes of dihalogermylene and dihalostannylene with 1,4-dioxane and PPh₃ have been reported, the structures of the complexes Cl₂Ge·C₄H₈O₂ and Cl₂Ge·PPh₃ updated using high-resolution X-ray method. Quantum-chemistry calculations of the geometry and normal mode frequencies and eigenvectors were carried out for some of the complexes. The results show that in the structure of the polymeric solid complexes of X₂M with 1,4-dioxane, intermolecular coordination XM plays a prominent role, whereas the corresponding complexes with PPh₃ are monomeric. In the vibrational spectra of all the complexes, an inversion of symmetric and antisymmetric stretching νXM (X=Cl, Br; M=Ge, Sn) frequencies, found for ‘free’ X₂M^II particles, still persists, suggesting that the X₂M moieties preserve their specifity as carbene analogues also in the complexes.     

Preparation and crystal structure of the La2Ni12P5 and isotypic ternary lanthanoid—Nickel phosphides

The new ternary phosphide La₂Ni₁₂P₅ has been prepared by direct arc melting of the components as pure metals and red phosphorus. The crystal structure has been determined using X-ray single crystal diffraction data. The compound exhibits a new type of crystal structure, P2₁/m with lattice parameters a = 10.911(3), b = 3.696(2), c = 13.174(4) Å, β = 108.02(2)°, V = 505,2(6) ų, Z = 2. Atomic parameters least squares refinement of 116 independent variables (anisotropic approximation for thermal vibrations) employed 1 284 independent I_o(hkl); R_F = 0.0278 and R_W = 0.0287. The crystal structure is characterized by trigonal prismatic arrangement of phosphorus atoms stacking variant of infinite (with phosphorus centered) columns built by metal trigonal prisms ‖ [010]. Two or three such columns are connected through common edges (lanthanum atoms). The compounds RE₂Ni₁₂P₅ (where RE = Ce, Pr, Nd and Eu) display the same with La₂Ni₁₂P₅ crystal structure. Lattice parameters of these compounds have been refined using powder diffraction data.     

硝酸镧与冠醚(2, 2)配合物的晶体及电子结构研究

用X-射线单晶衍射法测定了硝酸镧与冠醚(2,2)配合物的晶体结构,发现其具有与报道的Eu(NO_3)_3(2,2)配合物不同的配位方式.晶体属于三斜晶系,空间群P(?),晶胞参数为a=10.312(2)(?);b=12.745(3)(?);c=8.917(2)(?);α=103.79(2)°;β=112.73(2)°;γ=83.68(2)°;V=1049.5(5)(?)~3;F(000)=587.88;Z=2.结构用重原子法解出;R值为0.0292.用INDO法计算了配合物的净电荷分布,电子结构、键级.结果表明,镧与配位原子间的键具有一定程度的共价性.镧的5d轨道对共价性的贡献最大,而4f轨道基本上不参与成键.La-N比La-O(醚)间存在较强的作用,增大了配合物的稳定性.     

Preparation and crystal structure of Nb6.74 Ta5.26S4 – a new compound in the ternary system Ta?Nb?S

Nb_6.74Ta_5.26S₄ has been prepared by high temperature techniques. The crystal structure has been determined from single crystal X-ray diffraction data (R/R_w = 0.0588/0.0655). The compound crystallizes in the orthorhombic space group Pnma with unit cell dimensions a = 959.11 (26) pm, b = 336.37 (10) pm, and c = 3282.51 (74) pm. The orthorhombic cell contains four formula units. Its structure is similar to that of Nb-rich sulfides, rather than to that of Ta-rich sulfides. The metal coordinations are capped distorted cubic prisms and pentagonal prisms while the coordinations of sulfur are capped trigonal prisms.     

Stability of Ibuprofen in its Inclusion Complex with β-Cyclodextrin

The ibuprofen--cyclodextrin inclusion complex was prepared by theco-precipitation method. The identity of the obtained product was verified by X-ray and thermogravimetric techniques. The effect of -cyclodextrin on the stability of ibuprofen was analysed.     

Synthesis of a new donor, BEDT-HBDST and crystal structures, electrical and magnetic properties of (BEDT-HBDST)2MX4 (M=Fe, Ga, X=Cl, Br), where BEDT-HBDST=2,5-bis(4,5-ethylenedithio-1,3-diselenol-2-ylidene)-2,3,4,5-tetrahydrothiophene

A novel conjugation-elongated bis(ethylenedithio)tetraselenafulvalene (BETS) type donor, 2,5-bis(4,5-ethylenedithio-1,3-diselenol-2-ylidene)-2,3,4,5-tetrahydrothiophene (BEDT-HBDST) and its magnetic and non-magnetic anion salts, (BEDT-HBDST)₂MX₄ (MX₄⁻=FeCl₄⁻, GaCl₄⁻, FeBr₄⁻ and GaBr₄⁻), were prepared. These four salts are isostructural and belong to the space group of P2/c. They showed semiconducting behavior with small activation energies (59-64 meV). The band structures of these salts are quasi one-dimensional and there is a midgap between the upper band and the lower band, since the degree of dimerization is significant in the stacking direction. The MX₄⁻ ions are located between the donor columns and near to the ethylenedithio moieties of the donor molecules. The magnetic susceptibilities of the FeCl₄⁻ and FeBr₄⁻ salts follow the Curie-Weiss law with Curie constants of 4.6 and 4.8 emu K mol⁻¹ (sum of the spins of S=5/2 and S=1/2) and negative Weiss temperatures of θ=−1.2 and −4.9 K, respectively, revealing a weak antiferromagnetic interaction of 3d spins of the FeCl₄⁻ and FeBr₄⁻ anions. The Fe?Fe (6.66-7.60 Å), Cl?Cl (4.81-4.82 Å) and Br?Br (4.74-4.77 Å) distances in the crystal structures of these salts are significantly long. Therefore, the direct magnetic interaction between the 3d spins of the nearest neighboring Fe³⁺ ions appears to be not readily accessible.     

Synthesis and Crystal Structure of 5-Amino-4-cyano-8-isobutyl-7-isopropyl-6-thiocarbamoyl-2-azabicyclo[2.2.2]oct-5-en-3-thione

5-Amino-4-cyano-8-isobutyl-7-isopropyl-6-thiocarbamoyl-2-azabicyclo[2.2.2]oct-5-en-3-thione was synthesized by the condensation of isovaleryl aldehyde with cyanothioacetamide. The structure of the product was established by X-ray crystallography.     

Tetra(μ3-hydroxo)hexa(μ2-carboxylato-O,O′)-bridged tetranuclear terbium(III) cubane complex

A novel tetranuclear terbium(III) complex [Tb₄(OH)₄(pybet)₆(H₂O)₈][Tb₄(OH)₄(pybet)₆(H₂O)₇ (NO₃)](ClO₄)₁₄·6H₂O has been synthesized and shown by X-ray crystallography to have a cubane-like Tb₄(μ₃-OH)₄(μ₂-carboxylato-O,O′)₆ core. The ligand pybet is pyridinoacetate, C₅H₅⁺N-CH₂CO₂⁻. Magnetic susceptibility data were measured for this Tb₄ complex in the range of 2.0–320 K and in fields of 1.0 G to 50.0 kG. It is concluded that either there is very weak antiferromagnetic exchange interaction (J = −0.015 cm⁻¹) or there is a small crystal-field splitting of the ⁷F₆ Tb^III ground state.     

同步辐射白光全反射XRF在痕量元素检测的初步应用研究

叙述了同步辐射白光全反射Ｘ射线荧光分析的实验装置，给出了几种标准物质ＴＸＲＦ实验的检出限，并对实验结果进行了讨论。