Binuclear copper and zinc complexes based on polypyridyl ligand 2,3,5,6-tetra(2-pyridyl)pyrazine (tppz): Synthesis, spectral and structural characterization

The reaction of MCl2 · 2H2O (M = Cu, Zn) with 2,3,5,6-tetra(2-pyridyl)pyrazine (tppz) (referred hereafter as L) in 2:1 molar ratio in acetonitrile at room temperature afforded binuclear complexes [M2(κ3-L)Cl4] [Cu (1), Zn (2)] where the ligand is bis-tridentate manner. The complexes have been characterized by elemental analyses, FAB-MS, IR, EPR, NMR and electronic spectral studies. Solid state structures of both the [Cu2(κ3-L)Cl4] · 5H2O (1), [Zn2(κ3-L)Cl4] · H2O (2) have been determined by single crystal X-ray analyses. A well-resolved uudd cyclic water tetramer and water monomer were reported in the crystal host of [Cu2(κ3-L)Cl4] · 5H2O (1) and [Zn2(κ3-L)Cl4] · H2O (2) showing the contribution of the water cluster to the stability of the crystal host 1 and 2.