Crystals of the Kemp’s triacid salts. Part V: Structure of hydrogen-bonded complex of Kemp’s triacid with 7-methyl-1,5,7-triazabicyclo[4.4.0]dec-5-ene studied by X-ray and FT-IR methods

The 2:2 hydrogen-bonded complex between Kemp’s triacid (KTA) and 7-methyl-1,5,7-triazabicyclo[4.4.0]dec-5-ene (MTBD) has been synthesised and studied by X-ray and FT-IR methods. The crystals of KTA–MTBD are orthorhombic, space group is Pbca with a = 15.3435(9) Å, b = 13.0764(7) Å, c = 21.2403(14) Å, and Z = 8. In the solid state two protonated MTBD and two deprotonated KTA molecules form a hydrogen-bonded dimer. The dimer structure is stabilised by two OH⋯O− middle strength and two N+H⋯OC weak intermolecular hydrogen bonds as well as by two OH⋯O− very strong intramolecular hydrogen bonds. The existence of these three types of hydrogen bonds is well visible in the FT-IR spectrum of the complex and is discussed in detail.