Infrared study of the hydrogen bond complexes involving 2,3-bis-(2-pyridyl)-pyzazine and proton donors. Comparison with monofunctional heterocyclic N-bases.

The hydrogen bond complexes between phenols and 2,3-bis(2-pyridyl)-pyrazine BPP) are investigated by infrared spectroscopy in carbon tetrachloride solution. The formation constants for the complexes of 1-1 stoichiometry are higher than those predicted from the pK(a) of BPP. This is also the case for other N-heteroaromatic bases (Pyridazine, 2,2'-bipyrimidine) characterized by two vicinal equivalent nitrogen atoms. The thermodynamic and infrared data of the complexes show that BPP cannot be considered as a proton sponge.