Structural, spectral and theoretical aspects in the coordination of a triazine-based ligand toward lead(II) with a holodirected environment

Abstract

Listen

Translate article

Four complexes, [Cl(PPTA)2Pb(μ-Cl)2Pb(PPTA)2Cl] (1), [Br(PPTA)2Pb(μ-Br)2Pb(PPTA)2Br] (2), [I(PPTA)2Pb(μ-I)2Pb(PPTA)2I] (3) and [(PPTA)2Pb(NO3)2] (4), of 5-phenyl-3-(pyridin-2-yl)-1,2,4-triazine (PPTA) were prepared and identified by elemental analysis, FT-IR, 1H NMR spectroscopy and single-crystal X-ray diffraction. All the coordination modes of the 3-(pyridin-2-yl)-1,2,4-triazine-based ligands were studied by CSD software for predicting the behavior of the PPTA ligand in the reaction with metal ions. In the crystal structure of 1, the lead atom has a PbN4Cl3 environment with a distorted capped octahedral geometry. Complexes 2 and 3 are also dinuclear and isostructural with 1. The lead atom in the crystal structure of complex 4 has a coordination number of eight and a distorted cube geometry. The metal atom coordination spheres in all four structures tend to be holodirected with a decreasing deviation in the series 1–3. The thermodynamic stability of the isolated complexes and their charge distribution patterns were studied by DFT and NBO analysis. Theoretical studies reveal that the thermodynamic stability for the optimized complex 1 is more stable than those of the isostructural complexes 2 and 3.