Crystal structure of bis(3-carboxy-1-methylpyridinium) octabromide

Abstract

The crystal structure of the title salt, bis(3-carboxy-1-methylpyridinium) octabromide, 2C7H8NO2+·Br82−, consists of 3-carboxy-1-methylpyridinium (N-methylnicotinic acid) cations, which are stacked between relatively rare [Br8]2– anions. The polybromide [Br8]2– anion has point group symmetry \overline{1} and can be described as being composed of two [Br3]− anions connected with a Br2 molecule in a Z-shaped manner. Contacts between neighboring octabromide anions ensure the creation of pseudo-polymeric chains propagating along [111]. The organic cations are located between anionic chains and are connected to each other through O—H...O hydrogen bonds and to the [Br8]2– anions through π...Br interactions that induce the creation of a supramolecular tri-periodic network. In addition, the presence of weak C—H...Br contacts leads to the creation of layers, which align parallel to (11\overline{2}).

Keywords

• crystal structure
• octabromide anion
• polyhalogen ions
• n-methylnicotinic acid