Abstract
Solvothermal reactions of dimethyl pyridazine-3,6-dicarboxylate and appropriate metal chlorides in the absence/presence of KCl, NaCl or NH4Cl yielded a series of coordination compounds of pyridazine-3,6-dicarboxylate (pzdc) with Mn(II), Co(II), Ni(II) and Zn(II). All the Mn(II) compounds contain the anionic binuclear motif [Mn2(pzdc)3]2− with the trigonal prismatic shape. Through the K/Na-O electrostatic coordination, charge-assisted N–H⋯O hydrogen bonds, and weak C–H⋯O hydrogen-bonds, the binuclear prismatic anion co-assembles with different cations ([Mn(H2O)6]2+, K+, Na+ or NH4+) to generate 3D architectures. Under similar synthetic conditions, the Co(II) and Ni(II) ions always give the neutral binuclear molecules [M2(pzdc)2(H2O)4], which are self-assembled into 3D hydrogen-bonded networks. The Zn(II) ion seems to be amphibious: in the presence of NH4+, K+ and Na+, it forms the [Zn2(pzdc)3]2− species that are isostructural with the Mn(II) species, but the absence of the above cations leads to [Zn2(pzdc)2(H2O)4], which is isomorphous with the Co(II) and Ni(II) compounds. The different structures have been qualitatively explained based on the metal ionic size, ligand constraints, inter-ligand repulsion, ligand-field effects, and anionic–cationic interactions. Magnetic studies on selected Mn(II) compounds reveal that weak antiferromagnetic coupling is operative through the triple pyridazine bridges within the prismatic anions.
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have