Correlation of molecular mechanics with NMR spectroscopy: molecular geometry of nitrogen heterocycles

Abstract

In highly mobile molecules, e.g. five-membered rings, the assignment of vicinal coupling constants is difficult due to the similarity of all ³J values. A way of verifying assignments using MM2 calculations is reported. As MM2 calculations deal with the energy and geometry of individual conformations, whereas NMR data are averaged over all conformations, a way of correlating the two methods of study is provided.