Diverse Co(II) Coordination Polymers with the Same Mixed Ligands: Evaluation of Chemical Stability and Structural Transformation

Abstract

Reactions of Co(OAc)2·4H2O, N‚N’-bis(3-pyridylmethyl)oxalamide (L) and 4,4′-sulfonyldibenzoic acid (H2SDA) afforded four coordination polymers with the same mixed ligands, {[Co(L)(SDA)(H2O)2]·H2O·CH3OH}n, 1, {[Co(L)0.5(SDA)]·2H2O·0.5L}n, 2, {[Co(L)1.5(SDA)(H2O)]·H2O}n, 3, and {[Co2(L)1.5(SDA)2(H2O)2]·4H2O}n, 4, which have been structurally characterized using single-crystal X-ray crystallography. Complexes 1–4 are 2D layers, revealing topologies of sql, 2,6L1, (4,4)Ia, and 6L12, respectively, and demonstrating that the metal-to-ligand ratio, solvent system, and reaction temperature are important in determining the structural diversity. The immersion of these complexes into various solvents shows that the structural types govern the chemical stabilities of 1–4. Reversible structural transformation is shown for complexes 1 and 2 upon solvent removal and adsorption, while those of 3 and 4 are irreversible.

Keywords

• coordination polymer
• crystal structure analysis
• structural transformation