Xin Xinquan

Transformation of Sign of Nonlinear Refraction between Mo(W)/S/Cu Planar Metal Clusters

Optical nonlinear refractive properties of a series of Mo(W)/S/Cu planar square clusters are investigated using the Z-scan technique with the ns laser pulses at the wavelength of532nm. The result shows that the planar metal clusters containing the halogen ligands demonstrate the self-focusing effect, and the other planar metal clusters demonstrate the self-defocusing effect. These facts indicate that the halogen ligands can act as crucial factors in determining the sign of the nonlinear refraction of the Mo(W)/S/Cu planar metal clusters. The analysis of the experimental data shows that the planar clusters with halogen ligands possess greater refraction volume of the excited state than that of the ground state, while the other planar clusters possess the smaller refraction volume of the excited state than that of the ground state.

Syntheses and crystal structures of three polymeric cluster compounds +AgMoS4·α-MePyH+n, +AgMoS4·γ-MePyH+n and +AgWS4·γ-MePyH+n

Abstract The title compounds were obtained by reacting (NH4)2MS4 (M = Mo, W) and AgI with excess α-methylpyridine or γ-methylpyridine. The structures can be described as extended networks of AgS2M (M = Mo, W) as four-membered rhombs which are alternately parallel and perpendicular all along the polymer chain composed of continuous metal-metal bonds.

Synthesis and structural characterization of two novel heteronuclear cluster compounds, [NEt4]4[WS4Cu5Br7] and

Abstract The title compounds have been obtained by the reaction of [NH 4 ] 2 (WS 4 , CuBr, [NEt 4 ] 4 Br and [Bu n 4 N]Br in the solid state ( 1 ), or by the reaction of [NH 4 ] 2 [WS 4 ], CuI and [Bu n 4 N]I in the solid state and the pyridine substitution of the solid-state product in acetonitrile ( 2 ). X-ray diffraction analysis confirms that in the structure of 1 five of the six edges of the [WS 4 ] 2− tetrahedron are coordinated by CuBr units forming an open, double cubane-like structure, which possesses crystallographically imposed C 2 symmetry. The structure of 2 , which possesses a crystallographic 4 symmetry axis situated at the tungsten atom, consists of a tetrahedral WS 4 core enveloped by an octahedral array of six copper atoms, forming a WS 4 Cu 6 aggregate. Linked by Cu eq ICu eq  bridges, this aggregate connects with its nearest neighbours and develops a two-dimensional network. The substitution reactions of the solid-state product with pyridine are discussed.

ESSESA: An Expert System for Structure Elucidation from Spectra. 4. Canonical Representation of Structures

LNSCS (linear notation system of chemical structures), a chemical structure representation system, is designed to support the arbitrary notation for structures in ESSESA (expert system for structure elucidation from spectra). This paper describes a method for the canonical representation of chemical structures, the canonical renumbering of structures, the unique notation and the canonicalization algorithm, and the conversion from LNSCS to the canonical connection table. The first stage of the algorithm is the partitioning of the atoms in a structure, the molecule being treated as a graph with nodes (atoms) and edges (bonds). The partition is done by a product of the extended order value method, the initial order value is generated from the atomic character of the atoms in the structure. The program of converting LNSCS code to the canonical connection table consists of three parts, the compiling procedure of LNSCS and partitioning and generation of the canonical connection table. The algorithm by product of extended order value method is found to be more effective than the Morgan algorithm and other published algorithms.

XPS and AES investigation of nanometer composite coatings of NiPZnX on steel surface (ZnX = ZnSnO3, Zn3(PO4)2, ZnSiO3)

Abstract In this paper, the physical chemistry nature of the NiPZnX coatings have been studied by weighing method, accelerated corrosion tests, tarnish test, high-temperature oxidation tests, Auger electron spectroscopy (AES) and X-ray photoelectron spectroscopy (XPS). The result shows that the surfaces of the coatings are homogeneous, polished, solid and with strong corrosion resistance.

Solid state reactions of coordination compounds by gas chromatography

Here we report a review of the results of our studies in recent years on reactions of coordination compounds in solid state at ordinary ard medium temperatures. The studies have been made mainly by means of gas chromatography coupled with various spectroscopic methods. The results are described with respect to the following aspects:

The effect of anions on the thermal decomposition of the hexaamminecobalt(III) cation

Abstract Thermal decomposition reactions of hexaamminecobalt(III) chloride in the presence of anion salts KY (Y = Cl − , Br − , I − , CN − , SCN − , OH − ) are investigated, mainly by gas chromatographic, infrared spectroscopic and X-ray diffraction methods. Kinetic parameters are calculated. The deammine activation energy is found to vary with the different anions (Y), increasing in the order OH − − − − , Br − − . Possible mechanisms and factors affecting the results are discussed.

ESSESA: An expert system for structure elucidation from spectra. 3. LNSCS for chemical knowledge representation

LNSCS (Linear Notation System of Chemical Structures) is a support for chemical knowledge representation in the form of a linear unambiguous code for processing and manipulating chemical structure information. Based on principles of molecular graph theory, LNSCS can notate chemical structures using a very small number of natural rules and can be very easily used by cb ‘miq’ LNSCS code is an unambiguous but not unique linear character string. By a transformat : x , . program it can be easily changed into a computer’s internal code. LNSCS may be used as an interface between computer and user in chemical knowledge-based systems and chemical substructure search systems. It has now been adopted by ESSESA as a tool to exchange chemical structure information between system and user.

Thermal decomposition of K3Co(CN)5L in hydrogen atmosphere and the influence of reduced iron powder

Abstract The thermal decomposition of K 3 Co(CN) 5 L (L = CN − , NO 2 − , N 3 − , NO) in a hydrogen atmosphere has been studied by gas chromatography. The first stage of thermal decomposition of these complexes is to release crystal water if contained, and the second stage is to dissociate the ligand at very high speed, with a large amount of heat being released when LN 3 − . Thirdly, the residual cyano-cobalt complex is further decomposed to form HCN, (CN) 2 and N 2 and a little NH 3 and CH 4 . In the presence of iron powder, the evolution of NH 3 is increased greatly, whereas HCN disappeared entirely. The influence of reduced iron powder upon the decomposition is also studied.

Synthesis and structure of cluster compounds containing 2,2 `-bipyridine as ligand

Abstract The cluster compounds [MOS3Cu3X(bipy)2] (M˭Mo, W; X˭Br, I) were prepared by reactions of (NH4)2MOS3, CuX, and bipy at room temperature and characterized by IR and elemental analyses. The structure of [MoOS3Cu3I(bipy)2] was determined by single crystal X-ray diffraction revealing that the compound consists of a nest-shaped core. The Mo atom is tetrahedrally coordinated by three S atoms and one terminal O atom. There are two types of copper atoms in the MoOS3Cu3 aggregate: two copper atoms are tetrahedrally coordinated and another copper atom is trigonally coordinated.