Cocrystals of Kemp's triacid. Part III: Structure of hydrogen-bonded complex of Kemp's triacid with 1,1,3,3-tetramethylguanidine studied by X-ray and FT-IR methods

The 2:2 hydrogen-bonded complex between Kemp's triacid (KTA) and 1,1,3,3-tetramethylguanidine (TMG) has been synthesised and studied by X-ray diffraction and by FT-IR spectroscopy. Cocrystals of KTA-TMG belong to the monoclinic system and crystallize in the space group is P2(1) with a = 10.5017(3) angstrom, b = 7.9504(3) angstrom, c = 11.8910(4) angstrom, beta = 104.004(4)degrees and Z = 2. The ring of the KTA mono-anion molecule exhibits a chair conformation with all three carboxylic groups in the axial positions and all three methyl groups in the equatorial positions. in the crystal of the complex, cooperative systems involving inter- and intra-molecular hydrogen bonds are formed. In the solid state two protonated TMG molecules and two deprotonated KTA molecules form a dimer in which three-dimensional hydrogen-bonded networks are found. (C) 2008 Elsevier B.V. All rights reserved.