Continuous regulation of the architectures of cupric tetrazolate coordination polymers via the pH and temperature

Abstract

Four cupric cluster based magnetic coordination polymers Cu8O(tta)12(ClO4)2⋅2H2O (1), [Cu5(tta)9]Cl (2), Cu3(OH)2Cl (tta)3 (3) and Cu3(tta)4Cl2 (4) (Htta = 1-H-tetrazole) have been prepared by the same starting materials of cupric chloride and tetrazole, with the only difference of reaction temperature and pH value tuned by inorganic perchloric acid, among which complexes 2 and 3 are initially reported. Notoriously, high temperature can promote the reducing tendency of Cu(II)-to-Cu(I) in Cu/tetrazole system, whereas reducing tendency was prohibited by pH value control using perchloric acid in this work to generate cupric tetrazolate coordination polymers. Furthermore, different cupric cluster secondary building units (SBUs) such as planar Cu4O, trigonal prism-like Cu8, linear Cu3(OH)2 and Cu3Cl2 as well as the overall framework topologies such as bcu, asc and bct were observed. The bonding nature of chloride shows regular variation from free anion, dative Cu⋯Cl bond and normal Cu–Cl coordination bond due to Jahn-Teller effect of Cu(II) ions.