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.