Synthesis, characterization and crystal structures of three diverse copper(II) complexes with thiophene-2,5-dicarboxylic acid and 1,10-phenanthroline

Three copper(II) complexes with thiophene-2.5-dicarboxylic acid (H(2)Tda) a nd 1,10-phenanthroline (phen) ligands have been synthesized and structurall y characterized: [Cu(Tda)(phen) (H2O)(2)]. 3H(2)O (1), [Cu(Tda) (phen)(2)]. 1/2H(2)Tda . 2H(2)O (2) and [(Cu(Tda)(phen) (H2O))(n)] (3). The Cu atom in all of the three complexes is in five coordinate, distorted square pyramid al environments. The thiophene-2,5-dicarboxylate molecule is monodentate in 1 and 2 in which the molecular structure is stabilized by intermolecular a romatic ring stacking interaction between the thiophene ring and the aromat ic rings in the 1,10-phenanthroline molecule and hydrogen bondings. In 3 th e thiophene-2,5-dicarboxylate ion is bis-monodentate and bridges the [Cu(ph en)(H2O)] units to form a one-dimensional polymer. Complex 2 shows quasi-re versible one-electron redox of Cu2+/Cu+ at 0.001 V vs SCE. Coordination env ironments of copper(IT) in the reported complexes and stacking interactions in 1 and 2 are compared with those in the copper(II) site of galactose oxi dase (GOase). (C) 1998 Elsevier Science Ltd. All rights reserved.