[Ingeniosuccinimide]

Could this pair of peaks represent a pair of rotamers or something else that relates them? What I noticed is that we have a kind of same ratio of peak intensities (a:a) vs. (b:b) and the same distance in ppm between the first a and b and another a-b. I'm not sure if that can tell me something?

[Dan]

They could be rotamers. They could also be diastereomers or just different compounds with similar structures. There is not enough information here to say with any confidence. If you can post the structure, the method of preparation, the full 13C and 1H NMR and MS then there might be enough to make an educated guess.

The best way to tell if you have rotamers is to get a spectrum at high temperature and see if the peaks coalesce.