Reaction of Nitrosonium Tetrafluoroborate with Nitroxyl Radicals

It was established by means of multinuclear magnetic resonance method (1H, 1 3C, 1 9F and 1 4N) that reaction of 2,2,6,6-tetramethyl-4-R-piperidin-1-oxyl radicals (R = H, OH, OMe, OCOPh, NHCOMe) with nitrosonium tetrafluoroborate gave rise to the corresponding 2,2,6,6-tetramethyl-1-oxo-4-R-piperidinium tetrafluoroborates. Linear correlations were found between the chemical shifts of atoms H4, C4 of cations and respectively σ1-constants of substituents R and chemical shifts of C4 atom calculated from increments of substitution. The conformational features of the generated nitrosonium cations are considered on the grounds of vicinal coupling constants J H H and quantum-chemical calculations by AM1 method.