Journal of Physical Chemistry B, Vol.110, No.12, 5875-5882, 2006
Heteronuclear intermolecular resonance-assisted hydrogen bonds. The structure of pyrrole-2-carboxamide (PyCa)
The crystal and molecular structure of pyrrole-2-carboxamide (PyCa) determined by single crystal X-ray diffraction is presented. Molecular conformations of PyCa are also analyzed by FT-IR and NMR techniques. Additionally DFT calculations at the B3LYP/6-311++G(d,p) level of approximation are performed for dimers of PyCa and for related species. The existence of two tautomeric forms for the analyzed dimers differing in H-bond motifs, N-H center dot center dot center dot O or O-H center dot center dot center dot N, is studied. The geometrical and energetic features of such H-bonds show that these interactions may be classified as intermolecular resonance-assisted hydrogen bonds. Additionally the Bader theory is applied to determine and to analyze bond critical points.