Synthesis of some novel CoII and CoIII complexes by tribochemical reactions using KI with some derivatives of thiosemicarbazide complexes derived from Girard's T and P

The starting Co(II) complexes of the general formulae, [Co(L1)2]Cl4·4H2O, [Co(L1)Cl2]Cl (L1 = N-{[(allyl amino)thioxomethyl]hydrazinocarbonylmethyl}trimethylammonium chloride; ATHTC), [Co(L2)Cl]Cl·2H2O·(1/2)EtOH (L2 = N-{[(ethylamine)thioxomethyl]hydrazinocarbonylmethyl}trimethylammonium chloride; ETHTC) and [Co(L3)Cl2]Cl·2EtOH (L3 = N-{[(phenylaminomethyl)thioxomethyl]hydrazinocarbonylmethyl}pyridinium chloride; PTHPC), were synthesized by the conventional chemical methods. Tribochemical reactions of the above mentioned CoII complexes obtained by chemical methods with KI afford novel CoII and CoIII complexes with the general formulae [Co(L1′)I3·(1/2)EtOH]I, [Co2(L1′)I4]I·EtOH, [Co(L2′)I2·(3/2)EtOH]I, [Co2(L2′)I4(OEt)2(H2O)2]I·(1/2)EtOH and [Co(L3′)I2·H2O]I·3H2O. The ligands (L1′, L2′ and L3′) formed by tribochemical reactions are quite similar to these of L1, L2 and L3, except that the ionizable chloride ions in case of L1, L2 and L3 are substituted by iodide ions in (L1′, L2′ and L3′). The isolated solid CoII and CoIII complexes have been characterized by elemental analyses, conductivities, spectral (IR, UV–vis, 1H NMR) and magnetic measurements. The IR spectra of the starting CoII complexes indicate that both L1 and L3 behave in bidentate manner coordinating via the carbonyl oxygen and NH2 groups, but L2 behaves as a tridentate fashion coordinating via the carbonyl oxygen, azomethine (CN2) and SH groups with displacement of a hydrogen atom from the latter group. On the other hand, the IR spectra of the iodide CoII and CoIII complexes, synthesized by tribochemical reactions, suggest that L1′ behaves only in a bidentate fashion via NH1 and CS groups. L2′ behaves either as bidentate ligand through NH1 and CSH with deprotonation from the latter group or as a tetradentate ligand towards two cobalt ions via OH, CN2, CN1 and CSH with displacement of a hydrogen atom from the latter group. Moreover, L3′ behaves in a tetradentate ligand, toward two cobalt ions via the carbonyl oxygen, NH2, NH1 and CSH with displacements of a hydrogen atom from the latter group. The spectral and magnetic results suggest a tetrahedral geometry for all CoII complexes prepared by conventional chemical methods. The diamagnetic nature for three of the five iodide complexes, prepared by tribochemical reactions, suggests the oxidation of CoII to CoIII ion and the existence of low spin-octahedral geometry around the CoIII ion. Finally, the results of the rest of the iodide CoII complexes suggest either tetrahedral and/or high-spin octahedral geometry.