Speciation and transformation in the synthesis of Cu₄(im) ₄(C₄O₃H₆)₂(NO ₂)₄(H₂O)₄ and [(phen)Cu(C ₂O₄)(H₂O)]· H₂O

Two complexes, Cu₄(im)₄(C₄O ₃H₆)₂(NO₂)₄(H ₂O)₄ (1), [(phen)Cu(C₂O₄)(H ₂O)]∈•∈H₂O (2) (im∈=∈imidazole, phen∈=∈1,10-phenanthroline), were synthesized and structurally characterized by elemental analysis, IR, UV, TG and single crystal X-ray diffraction. During the synthesis of compound 1, citric acid lost two of its carboxylato groups and was decomposed into 3-hydroxybutanoic acid, the ions were reduced to ions. In compound 1, a tetranuclear Cu(II) complex was built up of four Cu(II) ions connected by two 3-hydroxybutanoic anions. In the preparation of compound 2, tartaric acid was decomposed into oxalic acid. Compound 2 is constructed by one phen, one oxalic anion and one water molecule coordinated directly to Cu(II).