1D, 2D and 3D coordination polymers of 5,5′-methylenebis(oxy)dinicotinic acid with Co(ii), Mn(ii), Cu(ii) and Cd(ii) ions

Abstract

A series of new coordination polymers of the 5,5′-methylenebis(oxy)dinicotinic acid ligand with various metal ions, have been synthesized under hydro(solvo)thermal conditions and characterized by X-ray crystallography: [Co(L)(H₂O)₄]_n (1), [Cu(L)(H₂O)₂]_n (2), two polymorphs of [Cd(L)(H₂O)]_n·(DMA)_n (3 and 4), [Co₄(L)₄(H₂O)₃]_n·(acetonitrile)_n (5), [Mn₂(L)₂(H₂O)]_n·(acetonitrile)_n (6) and [Cd₂(L)₂(H₂O)]_n·(DMA)_n·1½(H₂O)_n (7) (H₂L = 5,5′-methylenebis(oxy)dinicotinic acid; DMA = dimethyl acetamide) The hybrid metal–organic polymeric assemblies reveal diverse connectivity and topological features in one-, two- and three-dimensions, depending on the number of ligation sites available on the metal centers for binding the organic ligands and the nuclearity of connecting nodes. Compounds 1–4 involve mono-nuclear metal connectors and represent 1D and 2D coordination polymers. The three-dimensional single-framework polymers in compounds 5–7 are tessellated via dinuclear coordination nodes. Solid-state variable temperature magnetic susceptibility data of 5 and 6 involving the paramagnetic Co(II) and Mn(II) ions are reported as well. They reveal week anti-ferromagnetic coupling between the proxime metal centers observed in these two complexes.