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

Abstract

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