Coordination polymers with bulky bis(imidazole) and aromatic carboxylate ligands: Diversity in metal-containing nodes and three-dimensional net topologies

Five new three-dimensional transition metal coordination polymers (CPs) with dia and different aromatic carboxylates, [Cd(oba)(dia) _0.5] (1), [Cd(Hbtc)(dia)]•3H ₂O (2), and [M ₃(2-stp) ₂(dia) ₆(H ₂O) ₂] (3a, M = Cd; 3b, M = Co; 3c, M = Ni) were synthesized under hydrothermal condition (dia = 9,10-di(1H-imidazol-1-yl)anthracene; oba = 4,4′-oxybis(benzoate); btc = benzene-1,3,5-tricarboxylate; 2-stp = 2-sulfoterephthalate). Compounds 3a-c are isostructural. The coordination geometries at cadmium in 1, 2, and 3a are capped trigonal prism, pentagonal bipyramid, and octahedron, respectively. This diversity in coordination geometry is in sharp contrast to 3c and previously reported nickel complexes of a similar ligand set. The difference in metal-containing node geometries and carboxylate structures results in diverse network connectivity, including a tcs topology for 1, an unprecedented binodal topology of (4 ².6 ³.8 ⁵)(4 ².6) for 2, and a rare trinodal topology of (4.6 ⁴.8) ₂(4 ³.6 ³) ₂(4 ⁴.6 ¹⁰.8) for 3. Based on secondary building units, the networks in 2 and 3 can be, alternatively, described as rob and pcu (or ilc) nets, respectively. This work shows the effect of the specific ion and the rich potential of using bulky bis(imidazole) and aromatic carboxylate as ligands in the construction of CPs with unusual topologies.