Structural diversity of Ni(ii) coordination polymers containing dipyridyl amide and angular dicarboxylate ligands: synthesis, structures and magnetism

Abstract

Four new Ni(II) coordination polymers containing dipyridyl amide and angular dicarboxylate ligands, {[Ni(L¹)(MBA)]·2H₂O}_∞ [L¹ = N,N′-di(4-pyridyl)-adipoamide; H₂MBA = diphenylmethane-4,4′-dicarboxylic acid], 1, {[Ni(L¹)(OBA)]·H₂O}_∞ [H₂OBA = 4,4′-oxybis(benzoic acid)], 2, {[Ni(L¹)(SDA)]·2H₂O}_∞ (H₂SDA = 4,4′-sulfonyldibenzoic acid), 3, and {[Ni₂(L²)(SDA)₂]·6H₂O}_∞ [L² = N,N′-di(4-pyridyl)suberoamide], 4, have been synthesized by hydrothermal reactions and were structurally characterized by single crystal X-ray diffraction analyses. Complex 1 is a 1D → 2D polycatenane derived from the helical channels, and the 2D layers are further mutually interdigitated, whereas complex 2 forms 2D rhombic grids with the (6,4) topology, which are interwoven with each other to give a two fold 2D → 2D interpenetrating net. Complex 3 shows the 1D looped chain structure, and complex 4 shows 2D layers which catenate to each other to form a 2D → 3D inclined polycatenation framework with the new (4²·6⁸·8·10⁴)(4)₂ topology. The C–X–C (X = CH₂, 1; O, 2; and SO₂, 3 and 4) angles are important in determining the structural diversity. Complex 1 exhibits a different magnetic reaction in the ZFC and FC processes, revealing the existence of a meta-state of ferromagnetic ordering, whereas the activation energies of spin–orbit coupling and antiferromagnetic interaction of complexes 2–4 are directed by the N⋯N and Ni⋯Ni distances, respectively.