Synthesis and spectral studies ofN-2-pyridinylcarbonyl-2-pyridinecarxoximidate copper(II) complexes

Dimeric and polymeric copper(II) complexes containing BPCA (N-2-pyridinylcarbonyl-2-pyridinecarboximidate), having general formulae Cu(BPCA)X·nH2O (X=Cl, Br, NCS, NCO, N3, or CN) and Cu2(BPCA)2-X·nH2O [X=oxalate anion (OX), chloranilate anion (CA) or the dianion of 2,5-dihydroxy-1,4-benzoquinone (DHBQ)] have been synthesized by the copper(II)-assisted hydrolysis of 2, 4, 6-tris(2-pyridyl)-1, 3, 5-triazine. Spectroscopic results indicate five-coordinate, approximately square-pyramidal, geometry around the copper(II) ion. Half-field absorption in the ΔMs=±2 region of the X-band e.p.r. powder spectra has been observed for the dimeric species.

Study of the thermal behaviour of ordered bimetallic EDTA complexes

Abstract The study of the thermal behaviour of a family of isostructural ordered bimetallic MM'(EDTA)·6H 2 O complexes has been performed using TG and DTA. Formal kinetic analysis of the dehydration step has been approached using non-isothermal procedures. The resulting correlation among the calculated E a values and the cationic sizes implies a common dehydration mechanism. Copper-containing complexes show distinctive behaviour during the ligand pyrolysis processes. A mechanistic interpretation involving formation of Cu(I) and Cu(0) intermediates is furnished. The evolution of the inorganic residues in systems containing both Co and Ni is especially considered given the interest in the (Co…

Mono and dinuclear copper(II) complexes of 2,4,6-tris(2-pyridyl)-1, 3,5-triazine and halide or pseudohalide ions: Synthesis and spectral studies

By inhibiting the copper(II) assisted TPT (TPT = 2,4,6-tris(2-pyridyl)-1,3,5-triazine) hydrolysis, monomeric and dimeric copper(II) complexes having as general formulae Cu(TPT)X, · nH2O (X = Cl, Br, NCS, NCO or N3) and [Cu(TPT)X]2(PF6)2 · nH2O (X = Cl, Br, NCS or N3) have been synthesized and characterized by i.r., electronic and e.p.r. spectra, x-ray powder diffraction and analytical data. Spectroscopic results indicate five-coordinate geometry around the copper(II) ion, intermediate between trigonal-bipyramid and square-pyramid structures. The half-field absorption in the ΔMS = 2 region of powdered X-band e.p.r. spectra has been observed for the dimeric species.

ChemInform Abstract: Enhanced Surface Area in Thermally Stable Pure Mesoporous TiO2.

Abstract We describe here for the first time the surfactant-assisted synthesis of thermally stable mesoporous pure TiO 2 having a high surface area. Our synthetic approach to the chemistry of this system is based on the equilibrium between the hydrolysis and condensation reactions of the inorganic species and the organic–inorganic self-assembling processes. The use of titanatrane complexes helps to retard the hydrolysis and condensation reactions, thus allowing us to overcome the difficulties in preparing titanium dioxide mesoporous materials starting from highly reactive Ti-alkoxides. The mesoporous material has been characterized by TEM, XRD and N 2 adsorption–desorption isotherms and dis…

Ordered Mesoporous Silicon Oxynitrides

Ordered mesoporous materials: composition and topology control through chemistry

Abstract The atrane route constitutes a very versatile technique to obtain ordered mesoporous materials. A wide diversity of silica and silica-doped materials can be prepared by bringing into play fundamental synthesis parameters (like temperature, concentration and pH) which, in turn, allow modulation of the resulting material topology.

Crystal structure and spectroscopic studies of bis(N-2-pyridinylcarbonyl-2-pyridinecarboximidato)copper(II) monohydrate. Local bonding effects

Abstract The crystal and molecular structure of bis(N-2- pyridinylcarbonyl-2-pyridinecarboximidato)copper(II) monohydrate, Cu(BPCA)2·H2O, has been determined from single crystal X-ray data. It crystallizes in the monoclinic space group P21/c with four formula units in a cell of dimensions: a = 8.917(1), b = 8.932(1), c = 28.794(17) A, β= 95.49(2)°.Least- squares refinement of 2754 reflections with I > 2.5σ(I) and 379 parameters gave a final R = 0.037 (Rw = 0.036). The structure consists of discrete neutral Cu(BPCA)2 entities linked two by two through water molecules hydrogen bonded to ligand carbonyl groups. The coordination geometry around copper ions can approximately be described as orth…

Design of ordered bimetallic complexes, Part 2:Trans-1,2-cyclohexanediaminetetraacetate bimetallates

Knowledge of the kinetic and thermodynamic behaviour of aqueous solutions containing two divalent cations andtrans-1,2-cyclohexanediaminetetraacetate has been used to design synthetic pathways to ordered bimetallic complexes

Lactate complexes of molybdenum(VI)

Spectrophotometric and cryoscopic studies of the molybdenum(VI)-lactic acid (C3O3H6) system show the existence of three different oxoanion complexes in aqueous solution which have been isolated as [Co(en)3]3+ salts. These are one molybdodilactate {[MoO2(C3O3H42]2−} and two dinuclear 1/1 species: [Mo2O5(C3O3H4)2(H2O)2]2− and [Mo2O3(OH)3-(C3O3H4)2]−. The pH of the medium is the main variable, controlling the formation equilibria which are similar to those previously described for other α-hydroxy-acid ligands.

ChemInform Abstract: Crystal Structure and Spectroscopic Studies of Bis(N-2-pyridinylcarbonyl-2-pyridinecarboximidato)copper(II) Monohydrate. Local Bonding Effects

Abstract The crystal and molecular structure of bis(N-2- pyridinylcarbonyl-2-pyridinecarboximidato)copper(II) monohydrate, Cu(BPCA)2·H2O, has been determined from single crystal X-ray data. It crystallizes in the monoclinic space group P21/c with four formula units in a cell of dimensions: a = 8.917(1), b = 8.932(1), c = 28.794(17) A, β= 95.49(2)°.Least- squares refinement of 2754 reflections with I > 2.5σ(I) and 379 parameters gave a final R = 0.037 (Rw = 0.036). The structure consists of discrete neutral Cu(BPCA)2 entities linked two by two through water molecules hydrogen bonded to ligand carbonyl groups. The coordination geometry around copper ions can approximately be described as orth…

ChemInform Abstract: New Trends in V-P-O Solids

On the basis of the industrial interest of the oxovanadium phosphate catalysts, current research effort in this field is focused mainly on the development of synthetic strategies directed towards obtaining open-framework materials. There is a growing body of work describing preparations using hydrothermal procedures under a diversity of conditions. A great number of new solids, whose nets range from lamellar arrays to micro- and mesostructured organizations, has been prepared in last years. In this context, the applicability of concepts and procedures from the zeolites chemistry to systems involving transition elements is critically analyzed.

Complexes of molybdenum(VI) with organic diacid ligands: The molybdenum(VI)-malonic acid system

Malonic acid (C3O4H4) and MoVI form in aqueous solution two dinuclear dioxo-complexes of which the stability is a function of the pH of the medium. Both complexes have a 1∶1 metal-ligand stoichiometric ratio, and the interconversion may involve a structural rearrangement. Conditional dissociation constants have been determined spectrophotometrically. Saline cryoscopy supports the spectrophotometric results. Salts of [Co(en)3]3+ have been isolated. The ligand behaviour of malonic acid differs partially from that observed for α-polyhydroxy ligands.