Comparative Studies between Chemical and Tribochemical Reactions of Some Metal Complexes Derived from N-(O-Hydoxyphenyl)-N'-phenylthiourea (L)

The reactions of N-(O-hydoxyphenyl)-N'-phenylthiourea (L) derived from with Cu+, Cu2+, Co2+ and Co3+ chloride and/or iodide afford new metal complexes. The isolated complexes were synthesized by two different techniques (chemical and tribochemical methods). Two complexes were synthesized by the direct chemical reactions of N-(O-hydoxyphenyl)-N'-phenylthiourea (L) with MCl2·XH2O (M = Co2+ and Cu2+;X = 6 in case of Co2+ and X = 2 in case of Cu2+) in absolute EtOH. The general formulae of the two complexes derived by the chemical method are [Cu(L)2(EtOH)2]Cl2 and [Co(L)2Cl2]Cl. These complexes were used to synthesize another two complexes using tribochemical reaction by grinding the previous chloride complexes with excess KI in agate mortar in the solid state. The isolated complexes have the general formulae, [Cu(L)I·H2O]·1/2H2O and [Co(L)I3(Et- OH)]·3EtOH. The results indicate the substitution of the chloride by iodide ions during grinding and extraction of the complexes by solvents. The IR spectra of the complexes suggest that L acts in a bidentate manner towards the metal ions. Moreover, the results of electronic spectra and magnetic measurements for the chloride complexes suggest distorted-octahedral structure for Cu2+ and low-spin octahedral structures around the CoII and Cu2+ ions, respectively. On the other hand the data suggest that the iodide complexes have square-planer and low-spin for the Cu+ and Co3+ ions, respectively. The results of mass spectra confirm the formulae proposed for the isolated complexes. The mechanisms of reduction of CuII and oxidation of CoII for the metal complexes were elucidated.