A series of divalent metal coordination polymers based on isomeric tetracarboxylic acids: synthesis, structures and magnetic properties

Abstract

Five new coordination polymers, namely, [Mn(2,2′-bipy)(H₂O)₂(H₂L¹)]_n (1), {[Co(btb)(H₂O)₂(H₂L¹)]·0.5H₂O}_n (2), [Co(bib)(H₂O)₂(H₂L¹)]_n (3), [Ni₂(bpm)(H₂O)₃(L²)]_n (4), and {[Co₂(H₂O)₃(OH)(HL²)]·H₂O}_n (5), (H₄L¹ = 1,1′:2′,1′′-terphenyl-4,4′,4′′,5′-tetracarboxylic acid, H₄L² = 1,1′:2′,1′′-terphenyl-3,3′′,4′,5′-tetracarboxylic acid, 2,2′-bipy = 2,2′-bipyridine, btb = 1,4-bis(1,2,4-triazol-1-yl)butane, bib = 1,4-bis(imidazol-1-yl)butane, bpm = bis(4-pyridyl)amine), have been obtained under hydrothermal conditions. Complex 1 exhibits a 3D supramolecular framework based on 1D chains. Both complexes 2 and 3 are 3D supramolecular frameworks constructed from 1D zig-zag chains. Complex 4 features a 3D tetra-nodal (3,4,4,5)-connected architecture containing 1D μ-COO bridged chains with (5²·6²·7.9)(5²·6⁴·7³·8)₂(5²·6)₂(6³·7²·9) topology. Complex 5 shows a 3D penta-nodal (3,4,4,6,6)-connected net containing 1D μ-OH/μ-COO bridged chains and mononuclear Co(II) nodes with a (4²·6³·8)(4³)₂(4⁴·6²)₂(4⁴·6⁶·8⁵)₂(4⁴·6⁷·8⁴) topology. Variable-temperature magnetic susceptibility measurements reveal that complexes 2 and 3 show antiferromagnetic interactions between the adjacent Co(II) ions, whereas 4 is a ferromagnetic system.