Neutron diffraction studies of the 1:1 and 2:1 cocrystals of benzene-1,2,4,5-tetracarboxylic acid and 4,4?-bipyridine

Abstract

The 1:1 and 2:1 cocrystals of benzene-1,2,4,5-tetracarboxylic acid (BTA) and 4,4?-bipyridine (BPY) have been studied using neutron diffraction at 215 and 20 K, respectively. BTA and BPY crystallize in a 1:1 ratio with 1.8 molecules of water, viz. 4,4?-bipyridinium 2,5-dicarboxybenzene-1,4- dicarboxylate 1.8-hydrate, C10H12N2 2-·C10H4O8 2-·1.8H2O, (I), in the space group P1?, with both BTA and BPY lying on inversion centres. BTA and BPY crystallize in a 2:1 ratio, viz. 4,4?-bipyridinium bis(2,4,5-tricarboxybenzoate), C 10H12N22+·2C 10H5O8-, (II), in the space group Cc. The crystal structure of the 1:1 cocrystal contains one short N - H?O hydrogen bond [N?O = 2.6047 (19) Å] and one intramolecular O-H?O hydrogen bond [O?O = 2.423 (3) Å], The crystal structure of the 2:1 cocrystal contains two N - H?O hydrogen bonds [N?O = 2.639 (3) and 2.674 (2) Å], and two intramolecular [O?O = 2.404 (3) and 2.420 (3) Å] and four strong intermolecular O-H?O hydrogen bonds [O?O = 2.613 (3), 2.718 (3), 2.628 (3) and 2.739 (3) Å]. © 2006 International Union of Crystallography.