Effect of substitution of [Pd(PPh3)(4)] by related compounds as catalysts in reactions of organic syntheses

The effect of substitution of [Pd(PPh3)(4)], which is unstable in air, by complexes of the type [MCl2L2] (M = Pd, Pt; L = AsPh3, SbPh3), [PdL4](L = PPh3, AsPh3, SbPh3) and [NiX2(PPh3)(2)] on the syntheses of thioethers, acetylenes and ketones is described.

Thermoanalytical study of the complexes of 4-dimetilaminocinnamylidenepiruvate with manganese (II), cobalt (II), nickel (II), cupper (II), zinc (II) and lead (II), in the solid state

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Oxidation of nickel(II) cyclam and tetraglycine complexes by dissolved oxygen in the presence of sulfur(IV). Synergistic effects of manganese(III) and cobalt(III)

The autoxidation of [Ni-II(cyclam)](2+) (cyclam = 1,4,8,11-tetraazacyclotetradecane) and Ni(II)tetraglycine, accelerated by S-IV is studied spectrophotometrically by following the formation of Ni-III complexes.

Thermoanalytical study of the complexes of 4-dimethylaminocynnamylidenepyruvate with manganese (II), cobalt (II), nickel (II), cupper (II), zinc (II) and lead (II), in the solid state

Solid state compounds M-4-DMCP, where 4-DMCP is 4-dimethylaminocynnamylidenepyruvate and M represents Mn (II), Co (II), Ni (II), Cu (II), Zn (II) and Pb (II) were prepared. These compounds were studied by thermoanalytical techniques: thermogravimetry (TG), derivative thermogravimetry (DTG), differential scanning calorimetry (DSC), X-ray diffraction powder patterns and complexometric titration with EDTA. From the results obtained by the complexometric titration with EDTA, TG, DTG and DSC curves, was possible to establish the hydration degree, stoichiometry and thermal stability of the prepared compounds.

Cobalt(II) and nickel(II) complexes with djenkolic acid

Cobalt(II) and nickel(II) djenkolates CoC7H12N2O4S2. H2O (I) and NiC7H12N2O4S2. H2O (II) were synthesized by the reaction of potassium djenkolate with the respective chlorides. LR spectra suggested coordination via the COO- and NH2 groups for the ligands in both compounds. Visible absorption spectra confirmed the octahedral structure of the complexes. X-ray powder diffraction patterns were indexed in the orthorhombic and monoclinic unit cells with parameters: a = 11.35, b = 7.35, c = 6.85 Angstrom for I and a = 11.54, b = 7.45, c = 6.90 Angstrom, beta = 94.95 degrees for II.

Combination of nickel and titanium complexes containing nitrogen ligands as catalyst for polyethylene reactor blending

Ethylene was polymerized using a combination of Ni(diimine)Cl-2 (1) (diimine = 1,4-bis(2,6-di-isopropylphenyl)-acenaphthenediimine) and {Tp(Ms)*} TiCl3 (2) (Tp(Ms)* = hydridobis(3-mesitylpyrazol-1-yl)(5-mesityl-pyrazol-1-yl)) compounds in the presence of methyl-aluminoxane (MAO) at 30 degrees C. The productivity reaches a maximum at X-Ni = 0.75 (1400 kg of PE/mol[M] . h), and the produced polyethylene (PE) showed maximal melt flow index (0.13 g/10 min) and minimal intrinsic viscosity (2.24 dL/g) compared to polyethylenes obtained with different values of nickel loading fractions (X-Ni). Productivity intrinsic viscosity data, as well as melt flow index measurements markedly depend upon the content of the late transition metal, thus suggesting a synergic effect between nickel and titanium catalysts.

Thermal studies on nickel(II) 4-iodopyrazole complexes

This work describes the synthesis, IR and UV-Vis spectroscopic characterization as well the thermal behavior of the [NiCl2(HIPz)(4)]center dot C3H6O (1), [Ni(H2O)(2)(HIPz)(4)](NO3)(2) (2), [Ni(NCS)(2)(HIPz)(4)] (3) and [Ni(N-3)(2)(HIPz)(4)] (4) (HIPz = 4-iodopyrazole) pyrazolyl complexes. TG experiments reveal that the compounds 1-4 undergo thermal decomposition in three or four mass loss steps yielding NiO as final residue, which was identified by X-ray powder diffraction.

Syntheses and luminescent properties of tetrahedral nickel(0) complexes

Tetrahedral nickel(0) complexes [NiL4], [Ni(dppe)2] and [Ni(CO)2(SbPh3)2] (L=AsPh3, SbPh3, P(OPh)3, dppe=1,2-bis(diphenylphosphino)ethane) were prepared by reduction of NiCl2·6H2O with NaBH4 under N2 or CO atmosphere in the presence of the ligand. The complex [Ni(SbPh3)4] was also obtained by electrolysis at -1.3 V (Ag/Ag+), under a platinum gauze, of the system NiCl2·6H2O/SbPh3 (molar ratio=1:4). These complexes, both in the solid state and in solution, show an orange emission at room temperature, when excited with UV radiation. A qualitative molecular orbital diagram for the [NiL4] complexes is proposed. Electronic absorption spectra of the complexes show bands near 400 nm assigned as MLCT π*2e←d2t2. A 1A1←3T1 transition is suggested for the emission observed in these systems. Lifetimes in microsecond range were estimated from time-resolved emission spectra. Spectroscopic properties of the free ligands have also been investigated.

Thermal study of nickel(II) pyrazolyl complexes

The thermal behavior of the pyrazolyl complexes [NiCl2(HPz) 4] (1), [Ni(NCS)2(HPz)4] (2), [NiCl 2(HdmPz)4]·2H2O (3) and [Ni(NCS) 2(HdmPz)4]·2H2O (4) (HPz=pyrazole, HdmPz=3,5-dimethylpyrazole) has been studied by thermogravimetry (TG) and differential thermal analysis (DTA). The TG data indicated that the thermal stability of [NiX2(HL)4] (X=Cl, NCS) compounds varies depending on the pyrazolyl ligand in the following order HL=HPz>HdmPz. From the thermal decomposition of 3 and 4 it was possible to isolate the intermediate compounds [Ni(μ-Cl)2(HdmPz)2] (3a) and [Ni(μ-1,3-NCS) 2(HdmPz)2] (4a), respectively. The final products of the thermal decompositions of 1-4 were identified as NiO by X-ray powder diffraction. © 2005 Akadémiai Kiadó, Budapest.

Electropolymerization using binuclear nickel(II) Schiff base complexes bearing N4O4 donors as supramolecular building blocks

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Thermal analysis of coordination compounds. Part 1. Thermodecomposition of nickel(II) triphenylphosphine complexes with halides, nitrate, and thiocyanate

The compounds [NiX 2(PPh 3) 2] (where X is Cl -, Br -, I -, NO - 3, NCS -; and PPh 3 is triphenylphosphine) were prepared and characterized by infrared and atomic absorption spectroscopies and by carbon and hydrogen analyses. Simultaneous thermogravimetric (TG) and derivative thermogravimetric (DTG) curves of these complexes were recorded in air. The decrease in mass observed indicates conversion of the complexes to oxides. The thermal decomposition of the halogen and nitrate complexes occurred in a number of steps; the thiocyanate complex decomposed in a single step. © 1994.

Correlation between i.r. spectra and thermal decomposition of cobalt(II), nickel(II), copper(II) and mercury(II) complexes with piperidinedithiocarbamate and pyrrolidinedithiocarbamate

The thermal decomposition of pyrrolidinedithiocarbamate and piperidinedithiocarbamate complexes of CoII, NiII, CuII and HgII have been studied by thermogravimetry and differential scanning calorimetry. The decomposition intermediates and final products were identified by their X-ray diffraction patterns. The i.r. spectra are discussed in terms of the thermal decomposition pathways.

An investigation of cadmium(II) and nickel(II) adsorption by chitin graft covolymer

Chitin hydrogels of poly(vinylpyrrolidone) (VP) were prepared by means of the hydrogen peroxide graft copolymerization process. The effect of the VP grafted chain on water diffusion through the biopolymer was studied. Fourier transform infrared spectra of the VP-g-Ch showed an increase in the intensities of the hydroxyl and carbonyl stretching bands indicating a reduction in the hydrogen bonding of chitin. An investigation was undertaken regarding the adsorption of nickel(II) and cadmium(II) ions from aqueous solutions by the VP grafted chitin and the effects of the grafting degree on the Cd2+ and Ni2+ sorption were studied. The Cd2+ and Ni2+ adsorption equilibrium data correlate well with the Freundlich equation. The results indicate that the Ch-g-VP graft copolymer under investigation is a potentially powerful chelating material that can be employed for Ni2+ and Cd2+ ion removal from wastewater effluents. (C) 2004 Wiley Periodicals, Inc.

Synthesis and properties of branched polyethylene/high-density polyethylene blends using a homogeneous binary catalyst system composed of early and late transition metal complexes

Branched polyethylene/high-density polyethylene blends (BPE/HDPE) with a wide range of molecular weights, melt flow indexes (MFI), and intrinsic viscosity were prepared using the homogeneous binary catalyst system composed by Ni(alpha-diimine)Cl-2 (1) (alpha-diimine = 1,4-bis(2,6-diisopropylphenyl)-acenaphthenediimine) and {Tp(Ms*)} TiCl3 (2) (Tp(Ms*)=hydridobis(3-mesitylpyrazol-1-yl)(5-mesityl-pyrazol-1-yl)) activated with MAO and/or TIBA in hexane at two different polymerization temperatures (30 and 55 degreesC) and by varying the nickel loading molar fraction (x(Ni)). At all Temperatures, a non-linear correlation between the x(Ni) and the productivity was observed, suggesting the occurrence of a synergistic effect between the nickel and the titanium catalyst precursors, which is more pronounced at 55 degreesC. The molecular weight of the BPE/HDPE blends considerably decreases with increasing Al/M molar ratio. The melt flow indexes (MFI) and intrinsic viscosities (eta) are strongly affected by x(Ni), but the melting temperatures are nearly constant, 132 +/- 3 degreesC. Dynamic mechanical thermal analysis (DMTA) shows the formation of different polymeric materials where the stiffness vanes according, to the x(Ni) and temperature used in the polymerization reaction. The surface morphology of the BPE/HDPE blends studied by scanning electron microscopy (SEM) revealed a low miscibility between the PE phases resulting in the formation of a sandwich structure after etching with o-xylene.

New Ni(II)-sulfonamide complexes: Synthesis, structural characterization and antibacterial properties. X-ray diffraction of [Ni(sulfisoxazole)(2)(H2O)(4)] center dot 2H(2)O and [Ni(sulfapyridine)(2)]

The synthesis, structural characterization, voltammetric experiments and antibacterial activity of [Ni(sulfisoxazole)(2)(H2O)(4)] center dot 2H(2)O and [Ni(sulfapyridine)(2)] were studied and compared with similar previously reported copper complexes. [Ni(sulfisoxazole)(2)(H2O)(4)] center dot 2H(2)O crystallized in a monoclinic system, space group C2/c where the nickel ion was in a slightly distorted octahedral environment, coordinated with two sulfisoxazole molecules through the heterocyclic nitrogen and four water molecules. [Ni(sulfapyridine)(2)] crystallized in a orthorhombic crystal system, space group Pnab. The nickel ion was in a distorted octahedral environment, coordinated by two aryl amine N from two sulfonamides acting as monodentate ligands and four N atoms (two sulfonamidic N and two heterocyclic N) from two different sulfonamide molecules acting as bidentate ligands. Differential pulse voltammograms were recorded showing irreversible peaks at 1040 and 1070 mV, respectively, attributed to Ni(II)/Ni(III) process. [Ni(sulfisoxazole)(2)(H2O)(4)] center dot 2H(2)O and [Ni(sulfapyridine)(2)] presented different antibacterial behavior against Staphylococcus aureus and Escherichia coli from the similar copper complexes and they were inactive against Mycobacterium tuberculosis. (c) 2007 Elsevier B.V. All rights reserved.