Formation of coordination polymer and molecular complex of 4,4′-bipyridyl-N,N′-dioxide of manganese and zinc

A 1D-coordination polymer [{Mn3(C6H5COO)6(BPNO)2(MeOH)2}(MeOH)2]n (1) having benzoate as the anionic ligand and 4,4′-bipyridyl-N,N′-dioxide (BPNO) as bridging ligand is synthesized by reacting benzoic acid with manganese(II) acetate tetrahydrate followed by reaction with 4,4′-bipyridyl-N N′-dioxide. The bridging bidentate BPNO ligands in this coordination polymer along with the benzoate bridges hold the repeated units. The chain like structure in one dimension by benzoate bridges are connected to each other through the μ3-η2:η1 bridges of BPNO ligands. This coordination polymer can be transformed to a molecular complex [Mn(H2O)6](C6H5COO)2.4BPNO (2). In this complex the BPNO remains outside the coordination sphere but they are hydrogen bonded to water molecules to form self assembled structure. The reaction of 3,5-pyrazoledicarboxylic acid (L1H2) and BPNO with manganese(II) acetate or zinc(II) acetate led to molecular complexes with composition [M2(L1)2(H2O)6].BPNO·xH2O {where M = Mn(II) (3), Zn(II)(4)}. These molecular complexes of BPNO are characterised by X-ray crystallography. The complexes 3–4 are binuclear carboxylate complexes having M2O2 core formed from carboxylate ligands with two metal ions.

The complexation behaviour of 4,4′-bipyridyl-N,N′-dioxide towards manganese(II) and zinc(II) in the presence of benzoate or of 3,5-pyrazoledicarboxylate anions is studied. Mononuclear, dinuclear, and polynuclear complexes formed are structurally characterised.Figure optionsDownload as PowerPoint slideHighlights
► A coordination polymer of manganese benzoate and 4,4′-bipyridyl-N,N′-dioxide is synthesized.
► In the 1D-manganese polymer the chain like formed by benzoate bridges.
► The chains are interconnected to each other through 4,4′-bipyridyl-N,N′-dioxides.
► The manganese coordination polymer transforms to a molecular complex easily.
► The molecular complexes of manganese and zinc 3,5-pyrazoledicarboxylate are reported.