Ali M. Shaker

Synthesis and Characterization of Some Novel Amino Acid Schiff Base Fe(II) Complexes

New Fe(II) complexes of N‐salicylidene‐ and N‐naphthylideneamino acids (H2L) were prepared and characterized by elemental, electronic and IR spectral analyses, conductance and magnetic moment measurements and spectrophotometric determination of the stoichiometry. The stability and solubility of the prepared complexes were determined. The investigated Schiff bases exhibited monodentate divalent tridentate coordination and formed chelates of octahedral structures of the general formulae [Fe(HL)2]·nH2O and [FeL(H2O)3] where HL = mono‐anion and L = dianion of amino acid Schiff base ligand.

Kinetics of hydrolysis of some new heterocyclic azomethines

Kinetics of base hydrolysis of new heterocyclic azomethines derived from active methyl quaternary salts and aromatic nitroso compounds were investigated in the presence of 70% (wt/wt) water-methanol. The base hydrolysis of these compounds is strictly first-order with respect to OH− and azomethine. The rate determining step is suggested to be the attack of the hydroxide ion on the free base. Effects of water content and nature of organic hydroxylic solvent have been studied. It is concluded that specific solute-solvent interactions through dispersion forces play a major role in the base hydrolysis rate of the azomethines investigated. The effect of pH (2.98 – 12.24) on hydrolysis rates of compounds having a diethylamino substituent in the presence of 30% methanol has been studied. In acidic media, the rate determining step is probably the water attack on the protonated substrate.

Synthesis and Physico-Chemical Properties of Some Novel Amino Acid Azo Fe(II) Complexes

Some amino acids (DL‐phenylalanine (pha), DL‐tryptophane (trp), histidine (his) or alanine (ala)) were reacted with some nitroso compounds (N,N‐dimethylamino‐4‐nitrosoaniline (Nma) or N,N‐diethylamino‐4‐nitrosoaniline (Nea)) to form new amino acid azo compounds. These ligands interacted with Fe(II) ions in strong acidic media (pH≈1) to form complexes of the general formula [FeIIL2(H2O)2]X·nH2O, where X = SO4·or 2Cl, n = 2, 3 or 4 and L = amino acid azo ligands. All the complexes have been investigated and characterized by elemental, IR and UV‐Visible spectral analyses, magnetic and conductance measurements. The amino acid azo compounds acts as neutral and bidentate ligands by coordination through the α‐nitrogen of the azo group and the carbonyl of the carboxylic group. The effects of pH, as well as, the substituents of both amino acids or nitroso compound moieties on the stability and on the electrical properties of these azo Fe(II) complexes are discussed. The observed high stability of the tested complexes in the pH range 1.5–3 is attributable to the formation of a protonated dialkylamino group which enhances the stability of the azo complex. The electrical conductance data showed that, the conductivity and the stability of the studied azo complexes, increase with the stronger electron donating dialkylamino substituent on the nitroso compound moiety, in the order R′ = dimethylamino < diethylamino as well as, with the stronger electron withdrawing substituent of the amino acid moiety, in the order (R = indolyl < phenyl < imidazolyl). The stoichiometries of the studied complexes and their stabilities have been determined by a spectrophotometric continuous variation method and discussed in the light of structures and conductance data. The solubility of these complexes in water and water‐methanol solvent mixtures has been determined and discussed.

Synthesis and Properties of Zn(II)-Salicylidene Amino Acid Complexes

The synthesis of nine Zn(II) salicylideneamino acid complexes is reported. The structures of the complexes have been investigated by chemical analyses, electronic and infrared spectra, as well as molar conductance measurements. The apparent complex formation constants have been determined.ZusammenfassungEs wird die Synthese von neun Zn(II)-Salicylidenaminosäurekomplexen berichtet. Die Struktur der Komplexe wurde mittels chemischer Analyse, den Elektronen- und IR-Spektren und auch aus Leitfähigkeitsmessungen ermittelt. Die effektiven Komplexbildungskonstanten wurden ebenfalls bestimmt.

Salt effects on reactivities of low-spin iron(II) complexes of diazabutadiene and Schiff base ligands

Salt effects on reactivity are reported for base hydrolysis of tris-ligand-iron(II) complexes of several diazabutadiene and Schiff base ligands in aqueous solutions of alkali metal halides and of tetraalkylammonium bromides. The observed patterns vary markedly with ligand nature, the trend paralleling ligand hydrophilicity. These patterns of salt effects on reactivity are compared with those for a variety of other inorganic substitution reactions.