Current location: JICS Archive > Vol. 6 > No. 3 > Articles : 19

Synthesis and Crystal Structure of Mn(II) and Hg(II) Compounds and Solution Studies of Mn(II), Zn(II), Cd(II) and Hg(II) Compounds Based on Piperazinediium Pyridine-2,3-dicarboxylate

H. Aghabozorg^a,*, S. Daneshvar^b, E. Motyeian^c, F. Manteghi^a, R. Khadivi^d, M. Ghadermazi^e, A. Shokrollahi^f, M. Ghaedi^f, S. Derki^f and M. Shamsipur^g

^aFaculty of Chemistry, Tarbiat Moallem University, Tehran, Iran
^bDepartment of Chemistry, Islamic Azad University, Ardabil Branch, Ardabil, Iran
^cDepartment of Chemistry, Faculty of Science, Payame Noor University, Qom Center, Qom, Iran
^dDepartment of Chemistry, Islamic Azad University, North Tehran Branch, Tehran, Iran
^eDepartment of Chemistry, Faculty of Science, University of Kurdistan, Sanandaj, Iran
^fDepartment of Chemistry, Yasouj University, Yasouj, Iran
^gDepartment of Chemistry, Razi University, Kermanshah, Iran

Novel metal organic frameworks including {(pipzH₂)[Mn(py-2,3-dc)₂]·7.75H₂O}_n, 1, {(pipzH₂)[Zn(py-2,3-dc)₂]·4H₂O}_n, 2, [Cd(py-2,3-dc)(H₂O)₃]_n, 3 and {(pipzH₂)[Hg₄Cl₁₀]}_n, 4, in which pipz is piperazine and py-2,3-dcH₂ is pyridine-2,3-dicarboxylic acid were synthesized applying a proton transfer ion pair i.e.(pipzH₂)(py-2,3-dcH)₂ and corresponding metallic salts and studied by IR, ¹H NMR, ¹³C NMR spectroscopy and single crystal X-ray diffractometry. The space group of compounds 1 and 4 are P2₁/c and C2/c of monoclinic system, respectively. The crystal dimensions are a = 20.108(2) Å, b = 19.910(2) Å, c = 12.997(1) Å, β = 94.354(2)š for 1 and a = 15.940(1) Å, b = 11.2690(9) Å, c = 11.1307(9) Å, β = 90.685(2)š for 4. The crystal structures of 2 and 3 have been reported previously. However, their solution studies are discussed here. The compounds had all polymeric structures. Although Zn^II, Cd^II and Hg^II were elements of the same group, their behavior against the ion pair was essentially different. Various supramolecular interactions mainly hydrogen bonds of the type O-H···O, N-H···O, C-H···O, N-H···Cl and C-H···Cl were observed in the structures. There was an unusual and huge water cluster in the structure of compound 1. The solution states of compounds 1-4 were studied and reported. The protonation constants of pipz and py-2,3-dc, the py-2,3-dc/pipz proton transfer equilibrium constants and stoichiometry and stability of the system with Mn²⁺, Zn²⁺, Cd²⁺ and Hg²⁺ ions in aqueous solution were investigated by potentiometric pH titrations.

Keywords: : Metal complexes, Crystal structure, Solution study, Supramolecular chemistry, Water cluster