Mohamed I. Ayad

Cobalt(II) complexes with 2-aminoacetophenone N(4)-substituted thiosemicarbazones

Cobalt(II) complexes with 2-aminoacetophenone thiosemicarbazone and three N(4)-substituted thiosemicarbazones have been prepared in EtOH solution and characterized by physical and spectral methods. I.r. and electronic spectra of the thiosemicarbazones and their complexes, along with physical properties of the complexes, have been obtained. The 2-aminoacetophenone thiosemicarbazones coordinate both as neutral and anionic ligands via the thiosemicarbazone moietys imine nitrogen and thione/thiolato sulfur [on loss of the N(2) hydrogen].

Copper(II) complexes of 2-aminoacetophenone N(4)-substituted thiosemicarbazones

Mononuclear copper(II) complexes with 2-aminoacetophenone thiosemicarbazone and three N(4)-substituted thiosemicarbazones have been prepared in ethanolic solution and characterized by physical and spectral methods. I.r., electronic and e.s.r. spectra of the complexes, as well as i.r., electronic, and 1H- and 13C-n.m.r. spectra of the thiosemicarbazones, have been obtained. The 2-aminoacetophenone thiosemicarbazones coordinate as neutral ligands via the thiosemicarbazone moietys azomethine nitrogen and thione sulfur, except for the piperidylthiosemicarbazone, which undergoes deprotonation and coordinates via the thiolato sulfur, as well as through the azomethine nitrogen. Complexes formed in the presence of triethylamine also form complexes with the anionic form of these thiosemicarbazones.

MANGANESE(II), IRON(III), COBALT(II), NICKEL(II), COPPER(II), ZINC(II), and URANYL(VI) COMPLEXES of N-(4-FORMYLANTIPYRINE)BENZOTHIAZOL-2-YLACETOHYDRAZIDE

ABSTRACT Complexes of Mn(II), Fe(III), Co(II), Ni(II), Cu(II), Zn(II) and UO2(VI) with N-(2-furylidene)benzothiazole-2-ylacetohydrazide (HL) have been prepared in ethanolic solution and characterized by physical and spectral methods. IR, electronic, TGA and ESR spectra of the complexes, as well as IR, 1H NMR spectra of the ligand have been obtained. IR spectra show that the ligand coordinates either as neutral bidentate via the azomethine nitrogen and carbonyl oxygen or as a monobasic tridentate ligand via the enolic oxygen, azomethine nitrogen and furane ring oxygen. Stereochemistries are proposed for the complexes on the basis of spectral and magnetic studies.

Thermal behaviour of some aromatic diamine complexes

Abstract The Co(II) and Ni(II) complexes of some aromatic diamines were prepared and characterised by different analytical and spectral methods. The thermal behaviour of the investigated complexes was also studied. The thermal stabilities of the complexes were discussed in terms of chelate ring size and localised electron model.

Characterization and thermal behaviour of Cu(II) chelates of Schiff bases derived from aminopyridines

Abstract Complexes of copper(II) with Schiff bases derived from 3-amino- and 2-amino-pyridine and its derivatives with salicylaldehyde and o -hydroxynaphthaldehyde have been synthesized. The compounds have been characterized by elemental analysis, IR and electronic absorption spectra and differential thermal analysis. The data show the formation of two different types of compound with 1:1 and 1:2 metal-ligand stoichiometries and different thermal properties.

Effect of axial anions on the thermal stability of square pyramidal manganese(III) complexes

SummaryThe effect of the axial anion on the thermal behaviour of square pyramidal MnIII complexes of [Mn(SB)X] (where SB=tetradentate dibasic Schiff base; X=OAc−, SCN−, Cl−, Br− or I−) has been studied. A correlation has been made between the thermal stabilities of the complexes and the electronegativities (ξ) of the axial donor atoms. Other solid state phenomena (nature of interaction of the solvent of crystallization and polymorphic transformation) were also studied for the acetato and isothiocyanato complexes.

Synthesis, characterization and oxidase catalytic activity of vanadium(IV) and oxovanadium(IV) complexes with Schiff base ligands derived from β-diketones

New complexes of vanadium(IV) and oxovanadium(IV) with Schiff base ligands derived from β-diketones and ethanolamine or o-aminophenol have been prepared and characterized by elemental analyses, electrical conductance, magnetic moment measurements, and by i.r., u.v.–vis. and e.p.r. spectroscopy. A distorted octahedral environment was proposed for the vanadium(IV) and oxovanadium(IV) complexes. The spectroscopic results were utilized to compute the important ligand field parameters. Three adduct complexes were isolated owing to the interaction of one oxovanadium complex with Lewis-bases in MeOH. Vanadium(IV) complexes exhibit promising catalytic activity towards the aerobic oxidation of p-phenylenediamine (PPD) to the corresponding semi-oxidized form (PPD+). A linear correlation exists between the oxidase catalytic activity and the Lewis acidity of the central vanadium(IV) ion created by the donating properties of the parent ligand.

Tin(IV), titanium(IV) and hafnium(IV) complexes of some aromatic Schiff bases derived from 4-aminoantipyrine

SummaryTin(IV), titanium(IV) and hafnium(IV) chloride complexes of ligands such as salicylidene-4-aminoantipyrine (HL1), 5-chlorosalicylidene-4-aminoantipyrine (HL2), 2,4-dihydroxybenzylidene-4-aminoantipyrine (HL3), 2-hydroxy-1-naphthylidene-4-aminoantipyrine (HL4) and 2-hydroxyacetophenonylidene-4-aminoantipyrine (HL5) have been prepared and characterized. The analytical data show that tin(IV) forms only 1:1 metal complexes when reacted with HL1, HL3 and HL4, whereas it forms 1:1 and 1:2 metal complexes when reacted with HL2, depending on the molar ratio. HL5 produces only the binuclear complex SnHL5Cl4(H2O)SnCl4. Titanium(IV) gives only one type of complex of the general formula [Ti(HL)2Cl2]Cl2-2H2O, whilst hafnium(IV) gives HfHL3Cl4-4H2O and Hf(L5)2Cl2.

Investigation of Thiosemicarbazones as Chelating Agents. Synthesis and Spectroscopic Characterization of Some New Ruthenium(III) Complexes

New octahedral complexes of Ru(III) with salicylaldehyde, 5‐chlorosalicylaldehyde, 5‐methoxysalicylaldeyhyde, 2‐hydroxynaphth‐aldehyde and dehydroacetic acid thiosemicarbazones have been synthesized and characterized by elemental analyses, IR, UV‐Vis. spectra, magnetic moments, conductivity, ESR spectra and thermal analysis. The molar conductance measurements indicate that, the complexes are non‐electrolytes except for complex (L5H)2Ru]Cl·2H2O (10). The ESR spectra of the complexes (L5H)Ru(Cl)2(H2O)·2H2O (9) and (L5H)2Ru]Cl·2H2O (10), (L5H2 = dehydroacetic acid thiosemicabazone) show axial type symmetry (dxz), with mixed ionic‐covalent bond character. The electrochemical data for the complexes (1), (2) and (5) are discussed.

Thermal behaviour and electrical properties of some biologically active sulphonamide Schiff bases

Abstract The sulphonamide Schiff bases are thermolabile and undergo thermochromism and thermal decomposition after melting. The electric conduction properties of the Schiff bases were studied. In addition, the current-voltage dependence of the sulphonamide Schiff bases was investigated. This showed that the Schiff bases under investigation have ohmic conduction which is temperature independent.