An ab initio study of complexes with N-H-N hydrogen bonds /

Abstract

Ab initio MP2/6-31+G(d,p) calculations have been perlonned on a series of hydrogenbonded complexes stabilized by N-H-N hydrogen bonds. These complexes have 2,5- and 3,4-disubstituted pyrroles as proton donors (with substituents H, F, and Be+1 ), and nitrogen bases including HCN, LiCN, NaCN, SCN-, OCN-, NH3, and N(CH3)3 as proton acceptors. Correlations have been established among the structures, binding energies, proton-stretching frequencies, and intensities of the proton-stretching bands of these complexes. The great majority of complexes are stabilized by traditional N-H...N hydrogen bonds, with proton-shared and ion-pair hydrogen bonds occurring only in charged complexes.