Unusually Large 13C NMR Chemical Shift Differences Between Neutral and Protonated Glycocyamidines. New Insights on Previously Reported Chemical Shift Assignments and Chemical Properties.

Unusually large 13C chemical shift differences are observed between neutral and protonated glycocyamidine (2-aminoimidazolinone) derivatives. Upon protonation, the guanidine (N−CN) and carbonyl (CO...