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)]·3H2O
(2), and [M3(2-stp)2(dia)6(H2O)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 (42.63.85)­(42.6) for 2, and a rare trinodal topology of (4.64.8)2(43.63)2(44.610.8) 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.