Ekram A. Khalil

Conducting properties of some azo complexes

Electrical conductivities of 5-(P-substituted phenylazo)barbituric acid compounds and their complexes were measured. The results illustrate faint semiconducting behaviour for these systems. The conductivities were found to depend on the structure of the compounds. The metal ion forms a bridge between the ligands to facilitate the transfer of current carriers with some degree of delocalization in the excited state.

COMPUTERIZED ELECTRONIC SPECTRAL PROPERTIES OF SOME AZOBARBITURATE COMPOUNDS IN PRESENCE OF DIFFERENT SOLVENTS

The solvent effects on the spectra of 5-(p-substituted phenylazo) barbituric acid have been analyzed by the multiple linear regression technique using a Fortran IV program on a PC computer. The correlations based on one parameter equation gave that the solute permanent dipole-solvent induced dipole interaction (parameter M) plays the important role in determining the spectral shifts. The data based on two parameter equation gave that the solvent-solute hydrogen bonding combined with the solvent permanent dipolesolute permanent dipole interactions (E,N) are the important factors to explain the spectral shifts. For the three parameter correlations, the compounds with nitro, sulphonic, acetyl and iodo substituents gave that the combination ( , , ) gives a good fit to the observed spectral shifts. The HMO theory and the PPP method explain the phenomena of tautomerism of barbituric acid. The data predict that the diketo tautomer is the most stable one. Using the calculated PPP binding energy and singlets transition for the dienol tautomer which are nearly the same as those of the diketo tautomer to assign that a mixture of the diketo and dienol tautomers coexist. The agreement between the calculated and the experimental values of transition energies is reasonably good. The phenomena of tautomerism of barbituric acid is studied based on the Complete Neglect of Differential Overlap (CNDO) method. Calculations have shown that the dioxo form is the most stable tautomer. The singlets electronic transitions for 5-(p-substituted phenylazo) barbituric acid have been calculated by the CNDO method. The oscillator strength values of 5-(/>-substituted phenylazo) barbituric acid are calculated and found to be affected by other factors e.g., the dielectric constant of the solvent, the electronic property of the substituent and the solvation energy.

Complexing Properties of Some Pyrimidines

The synthesis of transition metal barbiturate, and thiobarbiturate complexes containing different functional groups of variable electronic character with CoII, NiII, CuII, PdII, and PtII have been prepared. The stereochemistry and the mode of bonding of the complexes were determined by elemental analysis and electronic and vibrational spectra together with their magnetic moment values. Electronic spin resonance of copper complexes were recorded. The Racah parameter of some cobalt and nickel complexes were calculated. Some of the complexes are of mixed stereochemistry. All the PdII or PtII complexes are of square planar geometries.

Ligating Properties of Some Arylazobarbituric Acids

Abstract The coordinating behaviour of 5-(arylazo) barbituric acid (aryl = 4-MeC6H4, 4-OMeC6H4, 4-COMeC6H4, 4-ClC6H4, 4-BrC6H4, 4-IC6H4, 4-NO2C6H4, 4-SO3HC6H4 and 4-CO2HC6H4) towards Fe (III), Co(II), Ni(II) and Cu(II) is investigated. The data suggest octahedral iron(III) complexes and 5- and 6-coordination for both cobalt(II) and nickel(II) complexes and 4- and 5-coordination for the copper(II) complexes in a dimeric skeleton through Cu-Cu interaction.

Spectral, Ligating Properties, and Electrical Conductivity of Some Azo-Nitroso Metal Complexes

Synthesis and characterization of new complexes derived from the interaction of 2,4-dinitrosoresorcinol (DNR) and 6-(o-substituted phenylazo)-2,4-dinitrosoresorcinol (X = -H, -OH, -COOH) with metal [Cr(III), Fe(III), Co(II), Ni(II) and Cu(II)] salts are reported. The structures of the complexes are achieved based on elemental analysis, spectral (UV, visible, and IR). The electrical conductivity of some ligands and their complexes favored their semiconducting properties. The thermodynamic parameters of thermal decompositions are evaluated.