Synthesis and characterization of CuII and CoII complexes derived from 2,4,6-tri-(2-pyridyl)-1,3,5-triazine (TPT) by chemical and tribochemical reactions

Abstract

Four CuII and CoII complexes–[Cu(L1)Cl2(H2O)]3/2H2O · 1/2EtOH, [Cu(L1)2Cl2]6H2O, [Co(L1)Cl2]3H2O · EtOH, and [Co2(L1)(H2O)Cl4]1.5H2O · EtOH (L1 = 2,4,6-tri(2-pyridyl)-1,3,5-triazine; TPT)–were synthesized by conventional chemical method and used to synthesize another four metal complexes–[Cu(L1)I2(H2O)]6H2O, [Cu(L1)2I2]6H2O, [Co(L1)I(H2O)2]I · 2H2O, and [Co2(L1)I4(H2O)3]–using tribochemical reaction, by grinding it with KI. Substitution of chloride by iodide occurred, but no reduction for CuII or oxidation of CoII. Oxidation of CoII to CoIII complexes was only observed on the dissolution of CoII complexes in d6-DMSO in air while warming. The isolated solid complexes (CuII and CoII) have been characterized by elemental analyses, conductivities, spectral (IR, UV-Vis, 1H-NMR), thermal measurements (TGA), and magnetic measurements. The values of molar conductivities suggest non-electrolytes in DMF. The metal complexes are paramagnetic. IR spectra indicate that TPT is tridentate coordinating via the two pyridyl nitrogens and one triazine nitrogen forming two five-membered rings around the metal in M : L complexes and bidentate via one triazine nitrogen and one pyridyl nitrogen in ML2 complexes. In binuclear complexes, L is tridentate toward one CoII and bidentate toward the second CoII in [Co2(L1)Cl4]2.5H2O · EtOH and [Co2(L1)I4(H2O)3]. Electronic spectra and magnetic measurements suggest a distorted-octahedral around CuII and high-spin octahedral and square-pyramidal geometry around CoII.