Sharif Digital Repository

Dinuclear cis-dioxomolybdenum(VI) complex [{MoO 2(Bz 2Benzenediyldtc)} 2] coordinated by a quadradentate dithiocarbamate (Bz 2Benzenediyldtc 2- = 1,4-benzenediylbis(benzyldithiocarbamate)(2-)) has been prepared and characterized by elemental analysis, 13C NMR, IR and UV-vis spectroscopy. The kinetics of the oxygen atom transfer between [{MoO 2(Bz 2Benzenediyldtc)} 2] and PPh 3 was studied spectrophotometrically in CH 2Cl 2 medium at 520 nm and four different temperatures, 288, 293, 298 and 303 K, respectively. The reaction follows second order kinetics with the rate constant k = 0.163(2) M -1 S -1 and its increasingly strong absorption at 520 nm clearly indicate the formation of a μ-oxo... 

Oxygen evolution was observed upon mixing solid manganese(III) bidentate Schiff base complexes with aqueous solutions of cerium(IV) ammonium nitrate. However, oxygen evolution was not observed upon mixing solutions of the complexes (in acetonitrile) with Ce(IV). Electron-withdrawing substituents on the Schiff base ligands (NO2, Br) enhanced the reactivity of the manganese complexes toward oxygen evolution. Oxygen evolution was also affected by R groups on the ligands, in the order Me > Et Bz. © 2009 Springer Science+Business Media B.V  

In this paper, the interactions of cobalt(III) tetradentate Schiff-base complexes, [Co(S-MeO-salophen)]ClO4, (1), [Co(5-NO 2-salophen)]ClO4, (2), and [Co(5-Br-salophen)]ClO 4, (3), with dopamine, an important neurotransmitter, have been investigated. The formation and kinetic constants for complex formation of [Co(3-MeO-salophen)]ClO4, (1), with dopamine were determined spectrophotometrically in H2O/EtOH solution (4:1) at 30°C by using the Benesi-Hildbrand and Guggenheim equations, respectively. The stoichiometry has been found to be 1:1. The rate and equilibrium constants for the coordination of dopamine to (Co(3-MeO-salophen)]ClO4 were found to be 0.0053 min-1 and 1600 dm3 mol-1,... 

Equilibrium constants for formation of a cobalt(II) complex with the bidentate ligand dopamine have been studied with spectrophotometric methods in water + ethanol cosolvent systems at 15, 25, and 35 (±0.1)∈°C and an ionic strength of 0.2 mol·dm-3. The ionic strength was maintained using sodium chloride and a phosphate buffer. The stability constants of the complex and the resulting Gibbs energy changes are obtained. The results are discussed in terms of the effect of solvent on protonation and complexation. © Springer Science+Business Media, LLC 2007  

The novel, unsymmetrical, mixed-donor, tetradentate amido, and oxo complexes of V(IV) of the general formula VOLx were synthesized by a nontemplate method and characterized by physico-chemical methods. The ligands were prepared by a two-stage aldol condensation reaction in the molar ratio 1:1 of 2-hydroxybenzaldehyde, 2′-hydroxyacetophenone, or 2′,4′- dihydroxyacetophenone and 1,2-diaminopropane of the general formula HA x (x = 1-3) as precursors. The tetradentate mixed donor ligands of the general formula H2Lx (x = 1-6) were obtained by condensation reaction of precursors with appropriate ketone or aldehyde. The synthesis of the ligand system, described here, is an efficient and easy method... 

The unsymmetrical tetradentate Schiff base H2L was prepared by the reaction of salicylaldehyde with the mono Schiff base derived from o-phenylenediamine and o-hydroxyacetophenone (HL1). NiL and CuL complexes were prepared and characterized by 1H NMR, IR and single crystal X-ray structure determination. Crystal data for NiL: triclinic space group P-1, a = 7.190 (2) Å, b = 13.059 (4) Å, c = 17.867 (10) Å, α = 74.888 (10)°, β = 84.206 (10)°, γ = 86.542 (2)° and z = 4. Crystal data for CuL: monoclinic space group P2I/n, a = 12.8209 (6) Å, b = 6.988 (3) Å, c = 18.601 (9) Å, β = 105.15° and z = 4. The Ni and Cu atoms have a slightly distorted square-planar coordination geometry  

The "half-unit" Schiff base, N-(2-hydroxyacetophenone)-1-amino-2-phenyleneimine (HL1), was used for the synthesis of some non-symmetrical tetradentate di-Schiff base complexes of Ni(II) and Cu(H). These complexes were characterized by elemental analyses, IR, electronic absorption spectra and molar conductance. 1H and 13C NMR spectra were obtained for the ligands HL1, H2L2 and H2L3. 1H NMR spectra suggest that the ligands in the Ni(II) complexes coordinate through the nitrogen atoms of the azomethine groups and the oxygen atoms of the phenolic (C-OH) groups  

Mn-doped ZnO nanoparticles, Zn1−xMnxO, were synthesised by a polyethylene glycol (PEG) sol–gel method and the physicochemical properties of compounds were characterised by atomic absorption spectroscopy (AAS), energy-dispersive X-ray analysis, X-ray diffraction, scanning electron microscopy and transmission electron microscopy. The catalytic degradation of an organic dye, methylene blue (MB), in the presence of Zn1−xMnxO as the catalyst and hydrogen peroxide (H2O2) as the oxidant at room temperature in water has been studied. Effects of oxidant, catalyst amount, catalyst composition, pH value of the solution and an OH-radical... 

Nanoparticles of manganese tungstate (MnWO4) were prepared via an impregnation method using Mn(NO3)2 4H2O and WO3 as a source of Mn and W, respectively. The morphology of the manganese tungstate nanoparticles was studied in detail by X-ray diffraction (XRD), scanning electron microscopy (SEM) and transmission electron microscopy (TEM). MnWO4 nanoparticles showed severe catalytic performances for the degradation of organic dye (methylene blue, MB) in the presence of tert-butyl hydrogen peroxide, TBHP, as the oxidant at room temperature in water  

The title complex [Mn(tptz)(CH3COO)(OH2) 2]NO3 was synthesized through the reaction of tptz (2,4,6-tris(2-pyridyl)-1,3,5-triazine), nitric acid and manganese(II) acetate. The molecular structure was characterized by X-ray diffraction, elemental analysis, electrochemistry, EPR, IR, fluorescence and UV-Vis spectroscopy and its oxygen evolving activity has been studied. X-ray structure analysis shows that each Mn(II) ion is seven coordinated by a bidentate acetate, three nitrogen atoms of tptz and two oxygen atoms from two water ligands, which are coordinated in axial positions. The complex acts as an oxygen evolving complex with oxone (2KHSO5·KHSO4·K 2SO4) as primary oxidant in aqueous... 

Charge-transfer (CT) complexes formed from the reactions of 4-nitropyrocatechol (4-nCat) as an electron acceptor with four amino alcohols: 2-aminoethanol, 1-amino-2-propanol, 4-aminobutanol and N-(2-hydroxyethyl)-1,3-diaminopropane (NHEDAP) as electron donors, have been studied spectrophotometrically in H2O and H2O/EtOH at 20, 25, 30, 35 and 40 °C. The calculated values of the oscillator strength and transition moment confirm the formation of CT-complexes. The thermodynamic and spectroscopic parameters were also evaluated for the formation of CT-complexes. The equilibrium constants ranged from 9.00 to 2.20 l mol-1 (M-1). These interactions are exothermic and have relatively large standard... 

The saccharinato complexes [Zn(phen)2(sac)(H2O)]sac (1) and [Zn(sac)(dmp)(H2O)](sac) (2), where phen = 1,10-phenanthroline, dmp = 2,9-dimethyl-1,10-phenanthroline, and sac = saccharinato ion/ligand, were synthesized by the reaction of [Zn(sac)2(H2O)4] · 2H2O with ligands and have been characterized by elemental analysis, IR, and 1H NMR spectroscopies. Conductivity of complexes was measured in DMSO. Compound 1 is characterized by single crystal X-ray diffraction and compared with some isomorphous zinc-saccharinate complexes reported previously. Complex 1 crystallizes in the triclinic system, space group P1̄, with Z = 2, and consists of alternating slightly distorted octahedral... 

A polymeric phenolato-bridged potassium compound, K(2-bromo-4,6 dinitrophenolate) (H2O), was obtained by reaction of methylammonium 2-bromo-4,6-dinitrophenolate and potassium chloride in water. 2-bromo-4,6 dinitrophenolate co-ordinates to the metal ion by phenolic O atom, Br, and O atoms of the nitro groups. K+ ion is eleven-coordinate in the compound. Single-crystal X-ray diffraction for methylammonium 2-bromo-4,6-dinitrophenolate and single-crystal X-ray diffraction, elemental analysis, IR, UV-Vis spectra, and fluorescence emission spectra for the complex have also been determined. Methylammonium 2-bromo-4,6-dinitrophenolate was solved in the monoclinic system, space group P21/c, with the... 

This article describes the synthesis and characterization of electronegative oxovanadium(IV) complexes containing tetradentate Schiff-base ligands derived from condensation of 1,3-propanediamine and 1,8-naphthylamine with 5-bromo-3-nitro-2-hydroxybenzaldehyde. New VOL1: [VO(5-Br-3-NO2salnaph)] and VOL2: [VO(5-Br-3-NO2salpn)] complexes were obtained in orange polymeric form with (V=O) stretching bands at 884 and 876 cm-1, respectively. The orange VOL1 and VOL2 complexes turn dark brown and green, respectively, when ground thoroughly in mortars. X-ray powder diffraction patterns of the ground VOL1 complex (VOL1g) scarcely show diffraction peaks. The data suggest that the linear chain polymeric... 

The solution equilibria of magnesium (II) complex formed with bidentate ligand of dopamine in acidic media (pH=∼4-∼6) have been studied in cosolvent systems at 15, 25, 35 ± 0.1° C and 1=0.2 mol.dm-3 sodium chloride, using phosphate buffer, with spectrophotometric methods. Evidence for the 2:1 complex was not observed for magnesium. The stability constant of the complex was determined KMg(HL)+ = ∼9 and the resulting free-energy changes obtained. The protonation constant of dopamine was determined under the above conditions. The results are discussed in terms of the effect of solvent on protonation and complexation  

Three ternary copper(II) complexes [Cu(5-bromo-salTyr)(bipy)]·1/ 2CH3OH (1), [Cu(5-bromo-salLue)(bipy)]·CH3OH (2) and [Cu(5-bromo-salTrp)(bipy)]·3CH3OH (3) (where 5-bromo-salTyr, 5-bromo-salLue and 5-bromo-salTrp are tridentate Schiff base ligands derived from the condensation of 5-bromosalicylaldehyde with tyrosine, leucine and tryptophan, respectively, and bipy is 2,2′-bipyridine) have been prepared and characterized by elemental analysis, electronic, IR spectroscopies, magnetic measurement and cyclic voltammetry. The complexes, 1 and 3 have been also structurally characterized by X-ray diffraction technique. Crystal structures of 1 and 3 complexes displayed a distorted square-pyramidal... 

New dioxomolybdenum(VI) complex was prepared by reacting 1-(2,4-dihydroxybenzylidene)-N-methyl-N-phenylthiosemicarbazone (H2L) as ligand and [MoO2(acac)2] in acetonitrile solution. The doubly deprotonated ligand is coordinated to molybdenum through sulfur atom, hydrazinic nitrogen atom and phenolic oxygen atom. The resulting complex with the formula [MoO2L(CH3CN)] which contains an acetonitrile molecule in sixth site of coordination, was characterized by elemental analyses, 1H NMR, IR and electronic spectroscopic studies and single crystal X-ray diffraction analysis. This complex was tested as a catalyst for the homogeneous epoxidation of olefins using tert-butyl hydrogen peroxide (TBHP) as... 

Conditions for an efficient ligand-free Heck C-C coupling reaction of aryl iodides and bromides with terminal olefins under aerobic conditions have been developed. Critical to the success of this new protocol is the use of palladium acetate as an extremely active catalyst for the Heck reaction in water and aqueous media. Both the base and the solvent were found to have a fundamental influence on the efficiency of the reaction, with K2CO3 and a mixture of (2:1) H2O/DMSO being the optimal base and solvent, respectively  

A polymeric manganese(II) complex with the general formula [Mn(O 2CCH2NH2CH2CO2) 2(H2O)2]n from reaction of iminodiacetatic acid and manganese(II) perchlorate under nitrogen in water, was synthesized and characterized. The structure of the complex was determined using single-crystal X-ray diffraction, elemental analysis, IR and UV-vis spectra. This complex exhibited excellent catalytic activity and selectivity for oxidation of various alcohols and sulfides to the corresponding aldehydes/ketone and sulfoxides using urea hydrogen peroxide and oxone (2KHSO 5·KHSO4·K2SO4), respectively, as oxidants under air at room temperature. The easy preparation, mild reaction conditions, high yields of the...