Preparation and Characterization of a Molecular Cobalt Complex Containing a Water Soluble Triazole Ligand

Cobalt(II) perchlorate hexahydrate, (Co(ClO4)2.6H2O) was reacted with a water soluble sulphonated pyridyl-triazole N,N-bidentate ligand (2-(1-((pyridine-2-yl)methyl)-1H-1,2,3-triazol-4-yl)ethyl sodium sulfate, `ligand 1.Na) in methanol to form [Co(ligand 1)2(H2O)2].4H2O as a microcrystalline solid. In this context, ligand 1.Na was first synthesized by the cycloaddition reaction of 2-(azidomethyl)pyridine and sodium 3-butyn-1-sulfate in 4:1 tert-BuOH/water solvents in presence of Cu(AcO)2H2O (10-15 mol %) as catalyst. The ligand 1.Na was white solid, absorbed moisture at open air, soluble in methanol and DMSO and characterized by elemental analysis, ESI-MS spectrum in the negative mode, 1H NMR and 13C NMR spectroscopy. In the 1H NMR spectrum of ligand 1.Na in CD3OD, a characteristic triazole strong singlet peak appeared at 7.97 ppm, a remarkable shift of δ value for CH2 proton of 2-(azidomethyl)pyridine was observed. In the 13C NMR spectrum, the triazole carbon resonates at 137.90 ppm. The prepared complex was characterized by physical data, FT-IR, ESI-MS and elemental analysis. The light pink crystals are fairly stable at open atmosphere even if they slowly loose the lattice solvent. The ESI-MS spectrum of [Co(ligand 1)2(H2O)2].4H2O indicates the species [Co(ligand 1.Na)(ligand 1)]+ and [Co(ligand 1.Na)]+ which corresponds to the m/z value at 648.6 and 402.6 respectively. Based on the observed data, octahedral geometry of the synthesized complex was suggested.