Synthesis, spectroscopy, thermal behavior, and X-ray crystal structure of two lead(II) complexes with 4′-(4- tolyl)-2,2′;6′,2″- terpyridine (ttpy)

Two new lead(II) complexes with 4′-(4-Tolyl)-2,2′; 6′,2″-terpyridine (ttpy), [Pb(ttpy)(μ-AcO)] ₂(PF ₆) ₂ (1) and [Pb(ttpy)(μ-AcO)I] ₂ (2), have been synthesized and characterized by CHN elemental analysis, ¹H NMR, ¹³C NMR, IR spectroscopy, and structurally analyzed by X-ray single-crystal diffraction. The thermal stability of these compounds has been studied by thermal gravimetric analysis and differential thermal analysis. Single crystal X-ray analysis shows that 1 and 2 are dimeric units with Pb-(μ-AcO)2-Pb-type bridging, and the coordination number in 1 is six and in 2 is seven. The arrangement of donors suggests a gap in the coordination geometry around lead, possibly occupied by stereo-active lone pair of electrons on lead(II), so the coordination sphere is hemidirected. Furthermore, dimeric units are connected by a network of hydrogen bonds and π-π stacking as well. Electrochemical properties of free ligand and complexes have been investigated in the presence of tetrabutyl ammonium perchlorate as supporting electrolyte and by using a glassy carbon electrode. Both lead complexes show irreversible Pb(II) oxidation. Cyclic voltammetry indicates that these processes are diffusion-controlled. The data from electrochemical studies show that the total limiting current of each of the studied complexes corresponds to two-electron transfer.