New Nuclear Quadrupole Resonance Frequencies at 14N in Saturated Cyclic Amines

The values of the nuclear quadrupole coupling constants $e^2\mathrm{Qq}$ of ¹⁴N and the asymmetry parameters $\eta$ in a series of saturated six‐, five‐, four‐, and three‐membered cyclic amines and of their N‐methyl derivatives have been measured at various temperatures, starting from liquid nitrogen temperature. Several resonance lines which could not be observed at 77°K, were detected at higher temperatures. By applying the Townes and Dailey theory to the experimental results, the electron populations of the atomic orbitals used by the nitrogen atom for the bonds with the carbon and hydrogen atoms have been evaluated. The values of the valence angles of nitrogen in the various kinds of molecules have also been evaluated. A particularly interesting result has been obtained for the four‐ and three‐membered cyclic amines.