FORMATION OF HYDROGEN-BONDED CHAINS BETWEEN STRONG N-BASE AND N-H ACIDS - A FTIR STUDY

Mixtures of imidazole derivatives with the strong base 7-methyl-1,5,7- triazabicyclo[4.4.0]dec-5-ene (MTBD) were studied by FTIR spectroscopy as a function of the imidazole derivative:MTBD ratio. In the case of complexes of MTBD with the lowest acidic imidazole only molecular comp lexes are found. This is true in the chloroform solutions as well as i n the acetonitrile solutions. With increasing acidity of the imidazole s in both solvents more and more polar structure of the complexes is f ound. In chloroform the polar structure predominates and the proton po larizability in the chains remains weak. In the acetonitrile solution the complexes dissociate. If more imidazole molecules are present one observes large proton polarizability of the negatively charged structu rally symmetrical imidazole chains. (C) 1998 Elsevier Science B.V.