Synthesis and Crystal Structure of CeIII and BiIII Complexes and Solution Studies of ZnII,CdII, PbII,CeIII, and BiIII Complexes Obtained from Proton Transfer Compounds Containing 2,6‐Pyridinedicarboxylate Ion |
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| Authors: | Shabnam Sheshmani Parvaneh Dalir Kheirollahi Hossein Aghabozorg Ardeshir Shokrollahi Guido Kickelbick Mojtaba Shamsipur Farshid Ramezanipour Abolghasem Moghimi |
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| Abstract: | The two complexes (pydaH)2Ce(pydc)2(H2O)2]2 · 2H2O (1) and (phenH)2Bi(pydc)2(H2O)]2 · 5H2O (2) were prepared from the proton transfer compounds containing the 2,6‐pyridinedicarboxylate ion. 1 was synthesized from the reaction of Ce(NO)3 · 6H2O with the proton transfer compound, (pydaH2)(pydc), (pyda=2,6‐diaminopyridine, pydcH2=2,6‐pyridinedicarboxylic acid). 2 was synthesized from the reaction of proton transfer compound, (phenH)2(pydc), (phen=1,10‐phenanthroline), with Bi(NO3)3 · 5H2O. The characterization was carried out using IR, 1H and 13C NMR spectroscopy, elemental analysis and single crystal X‐ray diffraction. The complex 1 crystallizes in the space group  of the triclinic system, and contains two molecules per unit cell. The structure has been refined to a final value for the crystallographic R factor of 0.0342 based on 8851 reflections. The unit cell parameters are: a = 9.753(2) Å, b = 10.503(2) Å, c = 10.774(2) Å, α = 83.905(4)°, β = 88.089(4)°, and γ = 82.636(3)°. The crystal structure illustrates that cerium atoms are connected together through the four‐membered ring Ce2O2. 2,6‐Pyridinedicarboxylate fragment acts as a tridentate ligand. The molecular structure contains four (pydc)2? ligands, two of which are bridge ligands linking the two central atoms. The complex 2 crystallizes in the space group  of the triclinic system and contains two molecules per unit cell. The unit cell dimensions are: a = 8.8860(4) Å, b = 12.0132(6) Å, c = 13.0766(6) Å, α = 100.967(1)°, β = 96.681(1)° and γ = 94.191(1)°. The structure has been refined to a final value for the crystallographic R factor of 0.0471 based on 9576 reflections. In this complex, 2,6‐pyridinedicarboxylate moiety has acted as a tridentate ligand and the lattice is composed of binuclear unit, Bi(pydc)2(H2O)]22?, (phenH)+ counter ions and five lattice waters. In both complexes hydrogen bonds, π‐π stacking and ion‐pairing play important roles in stabilizing the corresponding lattice. The stoichiometry and stability of the ZnII, CdII, PbII, and CeIII complexes with (pydaH2)(pydc) in aqueous solution were investigated by potentiometric pH titration. The solution studies revealed that the stoichiometry of the crystalline complexes of the proton transfer system (pydaH2)(pydc) with CeIII, obtained in this study, and those with ZnII, CdII and PbII, reported in our previous studies, are in close agreements. The complexation reactions of phen, pydc, and 2phen+pydc with BiIII in aqueous solution were investigated by potentiometric pH titrations, and the equilibrium constants for all major complexes formed are described. |
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| Keywords: | Cerium Bismuth 2 6‐Pyridinedicarboxylic acid Crystal structure Ion pairs Hydrogen bonds Solution studies |
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