Coordination of Carbon Dioxide to the Lewis Acid Site of a Zinc-Substituted Polyoxometalate and Formation of an Adduct Using a Polyoxometalate–2,4,6-Trimethylpyridine Frustrated Lewis Pair

The coordination of CO₂ to Lewis bases is well-known; however, its binding to Lewis acids is much less common. The ligation of CO₂ to a zinc-substituted Wells–Dawson type polyoxometalate yielded [(n-C₈H₁₇)₄N]₈[α₂-P₂W₁₇O₆₁Zn(CO₂)], which was studied by variable temperature ¹H NMR, ¹³C NMR, and ³¹P NMR spectroscopy from room temperature to 201 K. The spectra were analyzed in consideration of predicted “end-on” coordination, POM-Zn-O-C-O, and “side-on” coordination where in addition an adjacent basic oxygen atom in the polyoxometalate binds the carbon atom of CO₂. After adding 2,4,6-trimethypyridine into the solution, a plausible adduct, POM-CO₂-2,4,6-trimethypyridine, was observed.