Hydrogen bonds within an ionic environment:: The remarkable behavior of the zwitterion [CoIII(η5C5H4COOH)(η5-C5H4COO)]

The organometallic zwitterion [Co-III(eta(5)-C5H4COOH)(eta(5)-C5H4COO)] forms a hydrogen-bonded supramolecular adduct with the cationic acid [Co-III(eta(5)-C5H4COOH)(2)](+) in the solid state and shows self-organization around K+ cations in the mixed system {[Co-III(eta(5)-C5H4COOH)(eta(5)-C5H4COO)](2)}[K](+)[PF6](-).(eta(5)-C5H4COOH)(2)](+) (see Chart 1).(9) In the following we shall discuss self-assembly and HE interactions in crystalline [Co-III(eta(5)-C5H4COOH)(2)](+)[PF6](-) (1) and in the cocrystalline salt of the zwitterionic form [Co-III(eta(5)-C5H4COOH)(eta(5)-C5H4COO)] (see Chart 1), namely {[Co-III(eta(5)-C5H4COOH)(eta(5)-C5H4COO)][Co-III(eta(5)-C5H4COOH)(2)]}(+)[PF6](-) (2). Finally, we will discuss the intriguing interactions between zwitterions and K+ cations in {[Co-III(eta(5)-C5H4COOH)(eta(5)-C5H4COO)](2)}[K](+)[PF6](-) (3).(10).