Formation of hydrogen-bonded chains through inter- and intra-molecular hydrogen bonds by a strong base of guanidine-like character and 5,5′-dibromo-2,2′-biphenols

Abstract

5,5′-dibromo-2,2′-biphenol mixtures with 7-methyl-1,5,7-triazabicyclo[4.4.0]dec-5-ene (MTBD) were studied by FTIR as well as 1H NMR spectroscopy. In chloroform, a proton transfer from DBBPh to MTBD occurs and the protonated MTBD molecule is hydrogen-bonded to the chain formed between 5,5′-dibromo-2,2′-biphenol and 5,5′-dibromo-2,2′-biphenolate molecule. In acetonitrile, the complex dissociates and hence protonated MTBD molecules and hydrogen-bonded chains formed between 5,5′-dibromo-2,2′-biphenol and 5,5′-dibromo-2,2′-biphenolate are present. The hydrogen bonds of these chains show large proton polarizability.