Mn(II), Co(II), Ni(II) and Cu(II) chelates with3-phenyl-4-(p-methoxyphenylazo)-5-pyrazolone have been synthesized and were characterized by elemental and thermal analyses as well as
by IR, UV-VIS, 1HNMR, conductometric and magnetic measurements. The first stage in the thermal decomposition process of these complexes shows
the presence of water of hydration, the second denotes the removal of the coordinated water molecules. The final decomposition
products were found to be the respective metal oxides. The data of the investigated complexes suggest octahedral geometry
with respect to Co(II) 1:1, tetrahedral for Ni(II) 1:1and 2:3; square planar for Cu(II) 1:1 and 2:3; the complexes with no
coordinated water molecules (2:3) Co(II) and Mn(II) complexes are tetrahedral.
Authors:S. Abdel-Latif, O. El-Roudi, and M. Mohamed
Infrared (IR), nuclear magnetic resonance (NMR), thermogravimetric analysis (TG), derivative thermogravimetric analysis (DTG),
differential thermal analysis (DTA) and molar conductivity studies have been carried out on the chelates of Mn(II), Co(II),
Ni(II), Cu(II) and Zn(II) with 3-methyl- and 3-phenyl-4-nitroso-5-pyrazolones. The solid chelates were synthesized, separated,
analyzed and their structures were elucidated. The data obtained show that almost all of the prepared chelates contain water
molecules in their coordination sphere. The initial stage in the thermal decomposition process of these chelates shows the
presence of water molecule, the second denotes to the intermediate products. The final decomposition products were found to
be the respective metal oxides. The NMR spectrum of 3-methyl-4-nitroso-5-pyrazolone ligand shows the existence of the oxime
rather than the nitroso form. 3-phenyl-4-nitroso-5-pyrazolone acts as a neutral bidentate ligand whereas 3-methyl-4-nitroso-5-pyrazolone
acts as monobasic bidentate ligand bonded to the metal ions through the two oxygen atoms of the carbonyl and nitroso groups.
The solid chelates prepared behave as non-electrolytes in DMF solution. The coordination numbers of the obtained chelates
using 3-methyl-4-nitroso-5-pyrazolone are four on applying the mole ratio 1:1 and six on using 1:2 mole ratio. In case of
using the ligand 3-phenyl-4-nitroso-5-pyrazolone the coordination number is six in both cases.