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)(mu-AcO)](2)(PF6)(2) (1) and [Pb(ttpy)(mu-AcO)I](2) (2), have been synthesized and characterized by CHN elemental analysis, H-1 NMR, C-13 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-(mu -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 pi-pi 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.