Spectra–structure relationship: Syntheses, characterization, single crystal X-ray structural studies and packing analyses of two novel copper(II) complexes: [Cu(pyridine)2(H2O)4](p-toluenesulfonate)2 and [Cu(β-picoline)2(H2O)4](p-toluenesulfonate)2

In an attempt to formulate spectra–structural relationship to provide information on coordination around copper(II) ion in aqueous solution, two novel copper(II) complexes were investigated. [Cu(py)2(H2O)4](p-toluenesulfonate)2, 1 and [Cu(β-pic)2(H2O)4](p-toluenesulfonate)2, 2(py = pyridine, β-pic = β-picoline) were isolated by addition of py and β-pic respectively to the hydrated Cu(p-toluenesulfonate)2 suspended in water–methanol (1:4) mixture. The newly isolated complexes have been characterized by elemental analyses, TGA, spectroscopic techniques (EPR, IR and UV/Visible), conductance, magnetic susceptibility studies and single crystal X-ray structure determination. structural studies revealed the presence of uncoordinated p-toluenesulfonate anions in both of the crystal structures. The copper cations coordinate to two py/β-pic and four water molecules; the six donor atoms span as a distorted octahedron in both case. The crystal packing in both the complexes 1 and 2 are stabilized by CHO, CHπ and ππ stacking interactions besides electrostatic forces of attraction.