Synthesis, Characterization and Comparative Thermal degradation study of Co(II), Ni(ΙΙ) and Cu(II) complexes with Asparagine and Urea as mixed ligands

Abstract

New Co(II), Ni(II) and Cu(II) complexes with urea and asparagine as ligands have been synthesized in (M:L1:L2) molar ratio (where M= Co(II), Ni(II) and Cu(II), L1 =urea, and L2 =asparagine) then identified by micro analytical data, molar conductance measurements, IR, 1HNMR, Mass, UV-VIS spectroscopies and magnetic susceptibility measurements. Thermal degradation studies were carried out by thermal analysis. These complexes have the general formula [M(L1)(L2)(H2O)n]Cl. The molar conductance values in DMSO solvent show the electrolytic nature of these complexes, indicating the outer-sphere coordination of the chloride anions with metal ions. The three complexes have an octahedral structure although urea has shown two modes of coordination. Thermal analysis study shows rapid decomposition reaction for Ni complex and the highest thermal stability for Cu complex. The kinetic parameters were determined from the thermal decomposition data using the Coats-Redfern method. Thermodynamic parameters were calculated using standard relations.

Synthesis and Spectroscopic methods on the complexation ofCoII, NiII and CuII

“…The Co ΙΙ complex is hexa-coordintion suggested (structure 1). This is based on the appearance of 14705 cm -1 and 16129 cm -1 in the spectra (Table 5 and Figure 5), which are attributed to the 4 T1g→ 4 A2g(ν2) and 4 T1g→ 4 T1g(ν3) transitions, respectively [33] [34]. The Co ΙΙ complex has a magnetic moment of 4.7 B.M, which is within the range described for a high-spin octahedral geometry around the Co ΙΙ ion [35], however the spectra of the third band assigned to ν1 cannot be observed due to the instrument's limited range (400-1000 nm).…”