Molecular structure of a complex formed between hydrobromide of 7-methyl-1,5,7-triazabicyclo[4.4.0]dec-5-ene and 5,5′-dibromo-2,2′-biphenol in crystal and solutions.

A complex of 5,5′-dibromo-2,2′-biphenol with 7-methyl-1,5,7-triazabicyclo[4.4.0]dec-5-ene hydrobromide has been studied using X-ray diffraction, FT-IR, and 1H NMR spectroscopy. In the crystal structure, a bromide anion is hydrogen-bonded with MTBDH+ cation and two hydroxyl groups of two 5,5′-dibromo-2,2′-biphenol molecules. In the solid state, the Br− anion is an acceptor in N+–H⋯Br−, and two O–H⋯Br− intermolecular hydrogen bonds. In chloroform and acetonitrile, the structure of the complex assumes a new structure due to almost complete dissociation of protonated MTBD molecule. In chloroform, the MTBDH+ cation is hydrogen-bonded with 5,5′-dibromo-2,2′-biphenol whereas in acetonitrile it is free and solvated by the solvent. In both cases, the 5,5′-dibromo-2,2′-biphenol molecule is hydrogen-bonded to the bromide anion. [Copyright &y& Elsevier]