Affiliation: | aDepartment of Chemistry, Faculty of Science, Alexandria University, P.O. Box 426 Ibrahimia, Alexandria 21321, Egypt bInstitut für Physikalische und Theoretische Chemie, Technische Universität Graz, A-8010 Graz, Austria cDepartment de Quimica Inorganica, Universitat de Barcelona, Diagonal 647, 08028 Barcelona, Spain |
Abstract: | Two new coordination polymers of copper(I) chloride and pyrazinic acid (pyz-H), namely [CuCl(pyz-H)2]·2H2O (1) and [Cu2Cl2(pyz)(H2O)]·H2O (2) have been prepared and characterized by spectroscopic, magnetic and crystallographic methods. The overall physical measurements suggest that 1 is diamagnetic and contains monodentate N-pyrazinic acid, whereas 2 is paramagnetic and contains tridentate N,N′,O- chelating bridging pyrazinato anion. In the structure of 1 as elucidated by X-ray single crystal analysis, the asymmetric units [CuCl(pyz)2] are linked together forming a zigzag chain with tetrahedral copper(I) environment. The two lattice water molecules form hydrogen bonds with the uncoordinated N atom and carboxylate group O atom of pyz-H molecules. The Cu–N bond lengths are 2.009(6) Å and Cu–Cl distances are 2.337(2) Å. Complex 2 has a three-dimensional structure with the chains [Cu(I)Cu(II)(C5H3N2O2)Cl2(H2O)] interconnected by [Cu(I)Cl2N] tetrahedral unit and [Cu(II)NO2Cl2] polyhedra. The Cu(I)–Cl and Cu(I)–N distances are 2.327(2)–2.581(2) Å and 1.988(6) Å, respectively, whereas the Cu(II)–Cl and Cu(II)–N bond lengths are 2.258(2), 2.581(2) Å, and 2.017(6) Å, respectively. Hydrogen bonds of the type O–HO are formed between lattice and coordinated water, and carboxylate oxygens of pyrazinato ligand giving rise to a three-dimensional network. The Cl− anions act as bridging ligands in both complexes. The magnetic data of complex 2 have been measured from 2 to 300 K and discussed. |