Syntheses, characterization, and magnetic properties of novel divalent Co/Ni coordination polymers based on a V-shaped pyridine ligand and dicarboxylate acids

Abstract

Solvothermal reactions of 3,5-bis(4-pyridyl)-pyridine (BPYPY) with 1,4-benzenedicarboxylate (1,4-bdc) and trans-1,4-cyclohexanedicarboxylic acid (trans-chdc) in the presence of Co(II) and Ni(II) salts in DMF/H₂O or DMA/CH₃CN/H₂O produced three new compounds, namely, {[Co₃(BPYPY)₂(1,4-bdc)₃(H₂O)₆]}_n (1), {[Ni₃(BPYPY)₂(1,4-bdc)₃(H₂O)₆]}_n (2), {[Co(BPYPY)(trans-chdc)_0.5(NO₃)]·(H₂O)}_n (3). These compounds were characterized by elemental analysis, IR spectroscopy, and X-ray single-crystal diffraction. Compounds 1 and 2 are isomorphous and present 3,4-connected 3-fold interpenetrating tfz network with a point symbol of {6³}₂{6⁴·8·10}₃. Compound 3 exists binuclear Co clusters which are linked by BPYPY and trans-chdc to generate a 4-connected cds network with the point symbol of {6⁵·8} and displays antiferromagnetic characteristics. In addition, the thermal stabilities of these new compounds have also been discussed in detail.