Synthesis, crystal structure, and magnetic properties of {[Cu(phen)]2(C4H2O4)2} • 4.5H2O with C4H4O4 = maleic acid

Reaction of CuCl2 . 2H(2)O, phenanthroline, maleic acid and NaOH in CH3OH/H2O (1:1 v/v) at pH = 7.0 yielded blue {[Cu(phen)](2)(C4H2O4)(2)} . 4.5H(2)O, which crystallizes in the monoclinic space group C2/c (no. 15) with cell dimensions: a = 18.127(2) Ohm, b = 12.482(2) Angstrom, c = 14.602(2) Angstrom, beta = 103.43(1)degrees, U = 3213.5(8) Angstrom(3), Z = 4. The crystal structure consists of the centro-symmetric dinuclear {[Cu(phen)](2)(C4H2O4)(2)} Complex Molecules and hydrogen bonded H2O molecules. The Cu atoms are each square-pyramidally coordinated by two N atoms of one phen ligand and three carboxyl O atoms of two maleato ligands with one carboxyl O atom at the apical position (d(Cu-N) = 2.008, 2.012 Angstrom equatorial d(Cu-O) = 1.933, 1.969 Angstrom, axial d(Cu-O) = 2.306 Angstrom). Two square-pyramids are condensed via two apical carboxyl O atoms with a relatively larger Cu...Cu separation of 3.346(1) Angstrom. The dinuclear complex molecules are assembled via the intermolecular pi-pi stacking interactions into ID ribbons. Crossover of the resulting ribbons via interribbon pi-pi stacking interactions forms a 3D network with the tunnels occupied by H2O molecules. The title complex behaves paramagnetically between 5-300 K, following the Curie-Weiss law chi(m)(T-theta) = 0.435 cm(3) . mol(-1) . K with theta = 1.59 K.