The abrupt green-to-yellow thermochromism observed for certain A2CuCl4 compounds has long been attributed to the presence of strong N-H hydrogen bonding in the low-temperature phase that favors square-planar CuCl4(2-) (green in color) through reduction of ligand-ligand repulsion. Weakening of the hydrogen bonding at higher temperature results in the transformation to (far more common) flattened...

Some new complexes of thiacetazone (Thz) and quinalizarin (Qz) with Mn(II), Fe(II), Co(II), Ni(II), Cu(II), Zn(II), Cd(II) and Pb(II) were prepared. The ligands and their metal complexes were characterized by phisco-chemical spectroscopic techniques. The spectral data suggested that the thiacetazone as a neutral bidentate ligand is coordinated with the metal ions through the N and S atoms. The ...

The Voronoi diagram is a fundamental geometry structure widely used in various fields, especially in computer graphics and geometry computing. For a set of points in a compact 3D domain (i.e. a finite 3D volume), some Voronoi cells of their Voronoi diagram are infinite, but in practice only the parts of the cells inside the domain are needed, as when computing the centroidal Voronoi tessellatio...

We search for the lowest-energy structure of XAu4 (X = C, Si, Ge, Sn) clusters and calculate the photoelectron spectrum for the lowest-energy isomer of each species. The gradual destabilization of the tetrahedral geometry from C → Si → Ge → Sn, as well as the structural transition from the tetrahedral to the square planar geometry from SiAu4 to GeAu4, indicate that the change of electronic prop...

We investigate the fine structure of the sp3 hybridized covalent bond geometry that governs the tetrahedral architecture around the central C(α) carbon of a protein backbone, and for this we develop new visualization techniques to analyze high-resolution x-ray structures in the Protein Data Bank. We observe that there is a correlation between the deformations of the ideal tetrahedral symmetry a...

The reaction of CoCl2.6H2O, 1,2,4-triazole, and H(2)O at 200 degrees C for 96 h yields purple rods of [Co2(trz)3Cl] (1; trz = 1,2,4-triazolate) in 90% yield. The structure of 1 consists of {Co(trz)3}n(n-) chains of Co(II) sites linked through tetrahedral sites of {CoN(3)Cl} geometry into a three-dimensional framework. The competing antiferromagnetic interactions of the octahedral and tetrahedra...

3D Hybrid Finite Element Finite Difference Time Domain (FE/FDTD) Method is developed and applied to the numerical modeling of antennas. The antenna geometry is modeled using tetrahedral finite element mesh. Pyramidal elements are introduced in the transition from unstructured tetrahedral elements to structured hexahedral elements. The finite element formulation incorporates the excitation of an...

the reaction of an equivalent of 2- mercaptoethyl ammonium chloride with an equivalent of 2,6-diformyl -4- methyl phenol produced monoamine which was reacted with half equivalent of 1,2-diamine ethane to produce ethylene-bis-6-(2-mercapto-ethyl-imine)-methyl -4- methyl phenol [h4l]. the ligand was reacted with metal ions[cr(iii), mn(ii), fe(ii), co(ii), ni(ii), cu(ii), zn(ii), cd(ii), and hg(ii...

The reaction of [PPhJ, NOS,] with CuCl and KSCN (1 :3:3) in acetone produces the yell-ow crystals of [PPh,], [WOS,(CuNCS),]. The crystals are triclinic, space group P1(2), z=2, a=12.4823(7), b=12.9224(7), c=18.6395(10)?, ?=83.907(5), ?= 73.152(4), Y= 65.194(4)'. The crystal structure was determined by single crystal Xray diffraction methods (Mo-K ?) and refined by least-squares calculations ...

In recent years, new challenges for scientific visualization have emerged as the size of data generated from simulations has grown exponentially. The emerging demand for efficiently storing, transmitting, and visualizing such data in networked environments has motivated research in graphics compression for 3D polygonal models and volumetric datasets. The most general class of volumetric data is...