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Synthesis, Characterization and Kinetics of Metal Complexes Containing Dithiocarbamate and Polypyridine

Rafat R., Siddigi K., Siddiqi M.

Polish Journal of Chemistry

2007

Vol. 81, nr 3

313-326

Complexes of the type [M(L)(ddtc)2], where M = Mn(II), Co(II), Ni(II), Cu(II) and Zn(II), L = 2,2'-bipyridine or 1,10-phenanthroline and ddtc = diethyldithiocarbamate, have been synthesized and characterized by elemental analyses, IR, electronic, EPR, 1H NMR spectral data, magnetic moment and conductivity measurements. The electrical conductivity of the complexes indicated them to be non-electrolyte in nitrobenzene. The spectroscopic evidences suggest that the complexes have an octahedral environment around the metal ion. Plot of log [Delta/Delta-Delta m] against time was linear suggesting first order kinetics of nuceophilic substitution of [Ni(bpy)(ddtc)2] by chloride ion in nitrobenzene. The results show that the rate of substitution is independent of the concentration of the nucleophile and depends only on the first power of the concentration of the complex.

Synthesis and Spectral Studies of a Novel 20-Membered Unsymmetrical Dinucleating [N8] Macrocycle and Its Bimetallic Complexes, M2LCln(ClO4)2 (n = 2, M = Co, Ni orCu; n = 4, M = Cr or Fe)

Siddigi K., Khalid M., Khan M.

Polish Journal of Chemistry

2006

Vol. 80, nr 3

377-386

A 20-membered octaaza unsymmetrical Schiff base macrocycle, 6,10,16,20-tetramethyl- 7,9,17,19-tetraphenyl[1,5,7,9,11,15,17,19]octaazacycloeicosa-5,10,15,20-tetraene dihydroperchlorate (Lx2HClO4), has been obtained as an off-white amorphous solid by refluxing a mixture of 1,3-diaminopropane, N-acetylaniline and excess HCHO in the presence of HClO4 in ethanol, characterized by physico-chemical and spectroscopic studies. Its reactions with transition metal salts have afforded air stable solids with stoichiometryM2LCln(ClO4)2 (n=2,M=Co,Ni orCu and n = 4,M=Cr or Fe).Magnetic moment, IR and UV-visible spectroscopic data confirm encapsulation of metal ions through chelation from unsymmetrical aza groups and additional coordination by counter ClO4 which maintains hexa coordination around the metal ions. A low-spin distorted square-pyramidal geometry with distorted C4v symmetry of basal plane has been indicated for Co2+ complex. EPR data on Cu2+ complexes have indicated a tetragonal distortion with g|| > g_ > 2.0 and G < 4.0 with orbital reduction factor K_ > K|| favouring the presence of exchange coupling around the Cu2+ environment.