Potassium hydrogen malonate: remarkable crystal and molecular structure

X-ray crystallographic investigations of potassium hydrogen malonate crystals reveal a very unusual structure in which malonic acid molecules and doubly ionized malonate ions exist in equal numbers. These two species a nected by strong hydrogen bonds in one direction and by potassium ions in the other directions. This seems to be the first observation of the simultaneous ence in a crystal of the two species dicarboxylic acid molecules and their charged ions.