Saeyda A. Abouel-Enein

Synthesis and characterization of some bi, tri and tetravalent transition metal complexes of N′-(furan-2-yl-methylene)-2-(p-tolylamino)acetohydrazide HL1 and N′-(thiophen-2-yl-methylene)-2-(p-tolylamino)acetohydrazide HL2

The tetradentate Schiff bases hydrazone ligands HL(1), HL(2) and their metal complexes have been prepared and characterized by analytical, spectral (IR, UV-vis, (1)H NMR and ESR), molar conductivity, magnetic and TGA measurements. The results show that all the metal complexes are non-electrolytes, except (2, 10 and 20) which have ionic nature. The ligands coordinate in keto-neutral form and act as bidentate or tridentate for all metal complexes, except complexes (4 and 12). The ligands react as monobasic tetradentate and tridentate for complexes (4 and 12), respectively. Octahedral/tetrahedral Co(II) and Ni(II), octahedral/square planar Cu(II), and octahedral Mn(II), Fe(III), Cr(III), Ru(III), Hf(IV) and Zr(IV)O geometries were proposed. The ESR spectra of copper complexes (12 and 14) indicate d(x2-y2) ground state with covalent bond character. The thermal decomposition and the types of crystallized water for some metal complexes were studied. The studied metal complexes are very weakly active against the tested microorganisms.

First raw transition metal complexes of salicylidene and 2- hydroxy-1-naphthylidene-N-cyanoacetohydrazone

Mn(II), Co(II), Ni(II), Cu(II) and Zn(II) complexes of salicylidene-N-cyano-acetohydrazone H2L1 and 2-hydroxy-l-naphthylidene-N-cyanoacetohydrazone H2L2 have been prepared in ethanolic solution and characterized by analytical, spectral, magnetic susceptibility, molar conductivity and TGA measurements. The analytical data show that all the complexes derived from H2L1 and H2L2 are formed in molar ratios 1M:2L, except the complexes of Mn(II), Co(II) and Cu(II) acetates of H2L2 and the complexes of Mn(II), Co(II) and Ni(II) acetates and CuCl2 of H2L1 are formed in 1:1 molar ratios. The conductance data show that all metal complexes are non-electrolytes. Electronic absorption spectra and magnetic susceptibility measurements proved that the prepared complexes have octahedral configuration except [Co(HL2)OAc] which has tetrahedral structure. The ligand field parameters were calculated for the Co(II) and Ni(II) complexes and the data show that the covalent character of the metal ligand sigma-bond is low. The ESR parameters of the Cu(II) complexes at room temperature were calculated. Thermal TGA for some solid complexes are reported.

Spectroscopic studies and thermal decomposition for (bis-(( E )-2-(4-ethylphenylimino)-1,2-diphenylethanone) Schiff base and its Co(II), Ni(II), Cu(II), Zn(II) and Cd(II) complexes prepared by direct and template reactions

A new Schiff base (bis-((E)-2-(4-ethylphenylimino)-1,2-diphenylethanone) containing four active coordination centers (ONNO) and its metal complexes have been synthesized and characterized by elemental analyses, spectroscopic methods, molar conductance, thermal and magnetic measurements. The tetrahedral and square planar trinuclear Co(II), Ni(II) and Cu(II) complexes (1–3), respectively, have been prepared by direct reaction, while the template reaction gives octahedral complexes (4–8) with different stoichiometries 3:1, 2:1, 1:1 (M:L). The ESR spectra of solid copper (II) complexes in powder form showed an axial symmetry with 2B1g as a ground state. The thermal decomposition mechanisms of metal complexes were studied. All the thermal decomposition processes ended with the formation of metal oxide. The thermal study showed that the complexes with different solvents of crystallization exercise different types of interaction. The kinetic and thermodynamic parameters have been calculated.

Structural, spectral, magnetic and thermal studies of 5-(thiophene-2-ylmethine azo) uracil metal complexes

Abstract Mono- and bimetallic 5-(thiophene-2-ylmethine azo) uracil complexes were prepared in a pure ethanol or ammoniacal solution. The complexes were characterized by elemental analyses, thermal analyses, magnetic moment and spectroscopic measurements. The infrared and 1H-NMR studies revealed that the ligand reacts with all metal ions in a neutral keto form. Also, the ligand behaves as a tridentate or bidentate and coordinated with metal ions by ONS, NS and ON donors atoms, where azomethane nitrogen atom, and/or sulfur atom of thiophene ring and oxygen atom of uracil ring are participated to construct mononuclear Co(II), Ni(II), Zn(II), bimetallic Cd(II); mononuclear Cu(II) and Mn(II) complexes, respectively. However, in case of bimetallic Co(II) 7 and Ni(II) 8 ammine complexes, the ligand bridge is considered to indicate the ligand has tetra- and pentadentate character toward two metal ions, respectively. The magnetic moment values and the Nujol mull electronic spectra showed that all complexes have an octahedral geometry, except Cu(II) complex, 4 has a square planar structure. All the thermal decomposition processes led to formation of metal oxides. The hydrated complexes displayed a higher thermal stability than that of ammine complexes. Theoretical investigations have also been carried out at CAM-B3LYP/LANL2DZ to study the structure of the ligand and its Mn(II) complex. The results confirmed the experimental discussion.