Synthesis and characterization of Co(II), Cu(II) and Zn(II) complexes with 1,1-cyclobutanedicarboxylic acid
文摘
The compounds of 1,1-cyclobutanedicarboxylic acid with cobalt(II), copper(II) and zinc(II) ions have been prepared in aqueous solutions. The complexes were characterized by elemental analysis, IR spectroscopy, thermal analysis (TG, DSC/DTA and TG-FTIR) and X-ray analysis. The polycrystalline cobalt(II) and zinc(II) complexes were obtained as the hydrated compounds Co(C6H6O4) · 2H2O and Zn2(C6H6O4)2 · 3H2O, whereas the polycrystalline copper compound is anhydrous Cu(C6H6O4). During slow recrystallization we obtained single crystals of cobalt(II) and copper(II) compounds where the number of water molecules is different from that of the polycrystalline compounds and the formula are [Co2(C6H6O4)2(H2O)3] (1) and [Cu(C6H6O4)H2O] (2). The polycrystalline cobalt(II) and copper(II) complexes crystallize in the monoclinic system, the zinc(II) compound crystallizes in the triclinic system. During heating the hydrated complexes lose water molecules and become anhydrous. Next the anhydrous compounds decompose to the corresponding oxides. The thermal decomposition is connected with the release of water molecules (328 K), carbon dioxide (502 K) and cyclobutanecarboxylic acid (546 K). The IR spectra of the salt are discussed.