The background for the investigation is described in the Introduction section. As indicated by the Reviewer, the present study is an extension of our previous OH···O binding studies. We have for some time wished to investigate the corresponding NH···O systems. The NH···O type of linkage has the advantage that a wide range of compounds can be investigated; in general, systems of the type NH···O=C with an intervening double bond are not tautomeric, in contrast to the corresponding OH···O=C systems. We have added a remark on this aspect to the Introduction section. - The ‘delay’ of 10 years is due to technical and personal factors of no relevance to the reported results.
In this article, the authors describe the spectral characteristics of NH in the hydrogen bridge NH...O. It is a continuation of similar OH...O binding studies performed 10 years ago. The rationale for undertaking the research is a bit puzzling. I am curious what prompted the Authors to deal with N-H...O bonding in place of the earlier O-H...O. The explanation should be cleared.