Fatma I. Taha

Electrochemical synthesis of benzoylglycine and ethylphthaloyl-glycine complexes of transition metal ions

SummaryThe direct electrochemical oxidation of metallic iron, cobalt, nickel and copper in Me2CO solution of benzoylglycine and/or ethylphthaloylglycine gave products with high yields. For each of the complexes, the electrochemical efficiency is commensurate with the metals being divalent. Conventional physical and chemical studies were used to characterize the isolated complexes and octahedral geometry was suggested for them on the basis of magnetic and electronic spectral studies. The i.r. spectra show that the ligands coordinate in a bidentate fashion; the carboxylate ion is monodentate. The molar conductances agree with the complexes being non-electrolytes.

Spectral and magnetic studies of polynuclear copper(II) complexes of Schiff base derived from ethylenediamine and ethylacetoacetate

SummaryThe Schiff base (L), prepared by the condensation of two molecules of ethyl acetoacetate and one molecule of ethylenediamine reacts with copper(II) chloride to give poiynuclear complexes of the type Cu3L Cl6, Cu4L Cl8, Cu5L Cl10, Cu6L Cl12, Cu7L Cl14 and Cu8L Cl16. Elemental analyses, molar conductivities, magnetic susceptibilities, x-ray powder diffraction and i.r. spectral studies have been used to characterize the complexes. The i.r. spectra show that the Schiff base binds in a tetradentate manner and the spectral and magnetic studies suggest the presence of a chlorine bridge between the copper atoms. The magnetic susceptibility of the complexes follows the Curie-Weiss law.

Complexes of copper(II) with some new thiocarbamide derivatives

SummaryA new series of thiocarbamides was prepared by the reaction of benzoylisothiocyanate with various amines namely 2-aminopyridine (H2LI), 3-aminopyridine (H2LII), 2,3-diaminopyridine (H2LIII), 2,6-diaminopyridine (H2LIV), o-phenylene diamine (H2LV), p-phenylenediamine (H2LVI) and ethylene diamine (H2LVII). The copper(II) complexes of these ligands were isolated and have been characterized by elemental analyses, molar conductivities, magnetic moments and spectral (visible, i.r.) measurements. I.r. spectra show that the ligands behave as dianionic or neutral tetradentates or as monoanionic or neutral bidentates. The [Cu(HLI)Cl]2 and Cu(H2LIV)Cl2 complexes are diamagnetic and the other complexes have normal magnetic moment at room temperature. Electronic spectral analyses show that Cu2(LIV)Ac2 is planar and the other complexes are tetragonally distorted octahedral. All the complexes are non-electrolytes.

Metal Complexes of a Schiff Base Formed by Condensation of S-Benzyl-dithiocarbazate with Biacetylmonoxime (H2BTC)

Abstract The synthesis and characterization of Co(III), Ni(II), Cu(II), Zn(II), Cd(II) and UO2 2+ complexes of biacetylmonoxime-hydrazine-S-benzyldithiocarbazate (H2BTC) are reported. Elemental analyses, molar conductance, magnetic moment and spectral (i.r., visible and n.m.r.) measurements have been used to characterize the complexes. I.R. spectral data show that the ligand behaves in a bidentate and/or tridentate manner. An octahedral structure is proposed for the Co(III) complex while a square-planar structure is proposed for both Ni(II) and Cu(II) complexes on the basis of magnetic and spectral measurements.

Ligational Behaviour of bis(Biacetylmonoxime)carbo-hydrazone (H3BMC) Towards Transition Metal Ions

Abstract The synthesis and characterization of Fe(III), Co(III), Co(II), Ni (II), Cu (II), Zn (II), Cd (II) and UOc complexes of bis(biacetylmonoxime) carbohydrazone (H3BMC) are reported. Elemental analyses, molar conductance, magnetic moment and spectral (i. r., visible and n. m. r) measurements have been used to characterize the complexes. I. r. spectral data show that the ligand behaves in a tetradentate and/or pentadentate manner. The behaviour of the ligand towards any metal ion depends on the type of anion and the preparative conditions. An octahedral structure is proposed for the Fe (III), Co (III), Co (II) and the Ni (II) complexes which were prepared from the chloride, bromide, nitrate or sulphate salts. A square-planar structure is proposed for Cu (II) and the Ni (II) complexes derived from the acetate and thiocyanate salts on the basis of magnetic and spectral measurements. H3BMC acts as an oxidizing agent towards Co (II) chloride forming a diamagnetic Co (III) complex. All the complexes are no...

The conformational equilibria and vibrational spectra, including infrared matrix-isolation spectra, of fluoroacetyl chloride and fluoroacetyl bromide

Abstract Infrared spectra of the title compounds as liquids and as unannealed and annealed solids at 85 K were recorded in the 4000-50 cm −1 range. Matrix-isolation spectra in argon and in nitrogen matrices were obtained at 14 K in a 1:500 ratio, with gas mixtures heated to various temperatures between 313 and 700 K. Unlike the situation for other haloacetyl halides, the matrix spectra did not change significantly after annealing to 30–36 K, revealing a barrier (gauche—anti) in excess of 10 kJ mol −1 . Raman spectra of the compounds were recorded as liquids at various temperatures and as amorphous and crystalline solids. From the variable temperature measurements, the enthalpy differences between the conformers were found to be: 6.2 ± 0.4 (liquid, Raman), 4.8 ± 0.5 (“vapour”, Ar matrix, IR) and 5.2 ± 0.5 kJ mol −1 (“vapour”, N 2 matrix, IR) for fluoroacetyl chloride; 4.2 ± 0.4 (liquid, Raman), 5.2 ± 0.5 (“vapour”, Ar matrix, IR) and 5.7 ± 0.5 kJ mol −1 (“vapour”, N 2 matrix, IR) for fluoroacetyl bromide, the anti conformer invariably being the more stable. A systematic study was carried out to determine the influence of various spectral parameters on the Δ H 0 values of fluoroacetyl bromide. The spectra were assigned to the anti and gauche conformers with a few discrepancies from the interpretations of earlier authors.

Synthesis and Physico-Chemical Studies on New Iron, Cobalt, Nickel and Copper Complexes of Some Carboxylic Acids

Abstract New metal complexes of carboxylic acids have been prepared by a new method based on the electrochemical oxidation of iron, cobalt, nickel and/or copper in non-aqueous solution. The complexes were characterized by analytical, conductivity, spectral and magnetic measurements. The Co(II) and Ni(II) complexes are suggested to have an octahedral structure with partially covalent metal to ligand bonds. The 10 Dq, β and B values agree with those reported for the proposed geometry. Cu(II) complexes possess a distorted octahedral structure. The proton-ligand formation constant, pKH a, of isonicotinic acid and the stepwise stability constants of its Fe3+, Co2+ and Cu2+ complexes have been determined potentiometrically in dioxane-water (1:1). The stabilities of the formed complexes were found to be in the order Fe3+ > Cu2+ > Co2+ which agrees well with the Irving-Williams series.

Synthesis and Characterization of Some Transition Metal Complexes Derived from Dimedone bis(S-Benzyldithiocarbazic Acid)

Abstract Co(II), Ni(II), Cu(II), Zn(II) and Cd(II) complexes of 4,5-dimethyl-1,3-cyclohexanone bis(S-benzyldithiocarbazic acid), H2DSB, have been synthesised and characterized by elemental analysis, molar conductance, spectral (i. r., visible and n.m.r.) and magnetic moment measurements. I. r. spectra show that H2DSB behaves as a bidentate SS donor system in the copper chloride complex and a tetradentate SNNS donor system in the other complexes. Different stereochemistries are proposed for Co(II), Ni(II) and Cu(II) complexes on the basis of spectral and magnetic studies. The diamagnetic nature of Cu(H2DSB)2Cl.H2o suggest the reduction of Cu(II) to Cu(I). The molar conductivities for all complexes are reported in the range of non-electrolytes except that of the [Ni(H2)DSB)]Cl2.2H2O complex which suggest that it is a 1:2 electrolyte.