Betaine betainium hydrogen oxalate

The title compound, C5H12NO2+.C2HO4-.C5H11NO2 or HC2O4-. (HBET . BET)(+) [B ET is trimethylglycine (betaine); IUPAC name: 1-carboxy-N,N,N-trimethylmeth anaminium hydroxide inner salt], contains pairs of betaine molecules bridge d by an H atom, forming dimers linked by a strong hydrogen bond. The hydrog en oxalate anions have a rather unusual star conformation, with an internal torsion angle of 70.1 (4)degrees. The betaine-betainium dimers are anchore d between two zigzag chains of hydrogen oxalate molecules hydrogen bonded h ead-to-tail running parallel to the b axis. An extended network of C-H . . .O interactions links the anionic chains to the cationic dimers.