Dimethylammonium 2,4,5-tricarboxybenzoate: an example of the decarbonylation of N,N-dimethylformamide in the presence of a metal and a benzenepolycarboxylic acid. Is zirconium(IV) the Tsotsi?

Abstract

The title salt, C2H8N+·C10H5O8−, was the unexpected product of an attempt to prepare a ZrIV metal–organic framework with benzene-1,2,4,5-tetracarboxylic acid (1,2,4,5-H3B4C). In the reaction, the DMF solvent has been decarbonylated, forming the dimethylammonium cation, with one proton lost from the tetracarboxylic acid. It is proposed that the ZrIV salt acts as a Tsotsi or robber, plundering CO from the DMF molecule. The resulting salt crystallizes with two cations and two anions in the asymmetric unit. An intramolecular hydrogen bond forms between a carboxylic acid substituent and the carboxylate group of each of the monodeprotonated (1,2,4,5-H3B4C−) anions. In the crystal, an extensive array of O—H...O, N—H...O and C—H...O hydrogen bonds generates a three-dimensional network, with columns of cations and anions forming along the b axis.

Keywords

• crystal structure
• decarbonylation
• multiple hydrogen bonding
• 1,2,4,5-benzenetetracarboxylic acid
• Tsotsi