Molecular Beside Ionic: Crystal Structures of a 1/1 and a 1/4 Adduct of Pyridine and Formic Acid.

Of two low-melting binary adducts obtained with the same universal organic acid and base components, one contains these as the neutral molecules, the other, however, in a deprotonated and a protonated form as ions. Reports on analogous results for further Brønsted acid/base systems are rare. The complex anion, new in a crystal structure, is assembled by strong hydrogen bonds O-H⋅⋅⋅O (see formula).