Hydrogen-bond landscapes, geometry and energetics of squaric acid and its mono- and dianions: a Cambridge Structural Database, IsoStar and computational study

Hydrogen bonds involving squaric acid and its monoanion are similar in length and strength to those made by carboxylic acid donors and carboxylate COO^- acceptors, while hydrogen bonds accepted by the squarate dianion are somewhat stronger. The mono- and dianions have been added as new central groups to the Cambridge Crystallographic Data Centre's (CCDC) IsoStar knowledge base of intermolecular interactions.