Distorted Triple‐Diamond Structure of 3,3‐Bis(carboxymethyl)glutaric Acid (“Methanetetraacetic Acid”)

The construction of interpenetrating networks is the fascinating possibility of‐fered by tetracarboxylic acids containing tetrahedrally directed carboxyl groups. In the crystal they can form concatenated, diamondoid networks held together by pairs of hydrogen bonds. The cavities are filled owing to the interpenetration of several such networks. In the title compound C(CH2COOH)4 three translationally equivalent, tetragonally elongated diamondoid networks intermesh in a unique fashion. This kind of molecular architecture is a candidate for host structures in solid‐state inclusion compounds. In addition, these structures are models for novel substances exhibiting unusual properties (diamondoid polymers, ferroelectric compounds).