Current location: JICS Archive > Vol. 7 > No. 2 > Articles : 13
Two Novel Metal Organic Frameworks of Sn(II) and Pb(II) with Pyridine-2,6-dicarboxylic Acid and 4,4'-Bipyridine: Syntheses, Crystal Structures and Solution Studies
J. Soleimannejada, H. Aghabozorgb,*, S. Hooshmanda, M. Ghanbaric, F. Manteghid and M. Shamsipurc
aDepartment of Chemistry, Ilam University, Ilam, Iran
bFaculty of Chemistry, Tarbiat Moallem University, Tehran, Iran
cDepartment of Chemistry, Razi University, Kermanshah, Iran
dDepartment of Chemistry, Iran University of Science and Technology, Tehran, Iran
Two novel compounds with formulae [Sn2(pydcH)2(H2O)2O]n, 1, and (4,4΄-bpyH2)0.5[Pb(pydc)2(4,4΄-bpyH)].4,4΄-bpy.4H2O, 2, were obtained from a one-pot reaction between pyridine-2,6-dicarboxylic acid (pydcH2) and 4,4΄-bipyridine (4,4΄-bpy) with corresponding Sn(II) and Pb(II) salts. In compound 1 with a polymeric structure, each Sn(II) atom is six-coordinated by one water molecule, two (pydcH)- groups and one oxide group resulted in a coordination polymer. Compound 2 has a seven-coordinated environment around Pb(II) atom by two (pydc)2- groups and one (4,4΄-bpyH). The anionic complex is balanced by half a (4,4΄-bpyH2)2+ as counter ion. There are four uncoordinated water molecules and one 4,4΄-bpy in the crystal lattice. Therefore, in compound 2, we have neutral, mono- and biprotonated forms of 4,4΄-bipyridine, simultaneously. Several interactions including O-H∙∙∙O, O-H∙∙∙N and C-H∙∙∙O hydrogen bonds, ion pairing, C-O∙∙∙π (O···Cg 3.324(3) Åand 3.381(3) Å in 1 and O···Cg 3.346(4) Å in 2), C-H∙∙∙π (C···Cg 3.618(4) Å in 2), and π∙∙∙π stackings (with Cg ···Cg distances of 3.613(2) and 3.641 (2) Å in 2) are present to expand and stabilize the structure. The complexation reactions of bpy and pydc-bpy with Sn2+ and Pb2+ ions in aqueous solution were investigated by potentiometric pH titrations, and the resulting equilibrium constants and species distributions at various pHs for major formed complexes are described.
Keywords: Pyridine-2,6-dicarboxylic acid, 4,4'-Bipyridine, Sn(II) and Pb(II) complexes, Crystal structures, Solution studies
