Copper(II) and lead(II) complexes based on 2,3,5,6-tetrakis(2-pyridyl)pyrazine as a polydentate ligand

The Cu(II) complexes [Cu(Tppz)(Dipic)] ⋅ 8H2O (I) and [Pb2(Tppz)Cl4]n (II), where Tppz,H2Dipic are 2,3,5,6tetrakis(2pyridyl)pyrazine, dipicolinic acid, respectively, have been synthesized and characterized by elemental analyses, IR, cyclic voltammetry, and electronic spectral studies. Solid state structures of both complexes have been determined by single crystal Xray crystallography. An ORTEP drawing of two complexes shows that the coordination geometry around the metal center is a distorted octahedron. There are extensive conventional intermolecular O–H⋅⋅⋅O, N–H⋅⋅⋅O, and weaker C–H⋅⋅⋅O and C–H⋅⋅⋅Cl nonclassical hydrogen bonds, which cause the stability of the crystal structure. Crystal data for I: monoclinic, space group: C2/c, a = 35.421(3), b = 8.422(6), c = 22.824(8) Å, β =101.69(2)°, V = 6668(5) Å3, Z = 8. Crystal data for II: triclinic, space group P–1, a = 7.9534(4), b = 8.8682(5), c = 9.4245(5) Å, β = 95.086(2)°, V = 655.93(6) Å3, Z = 2.