Analysis of the proton, carbon, and nitrogen NMR spectra of cis,cis ‐ and cis,trans ‐1,3,5‐triaminocyclohexane

The proton spectrum of the isomeric mixture of cis,cis ‐ and cis,trans ‐1,3,5‐triaminocyclohexane was assigned with a 2D COSY experiment. Using Forrest's modified equation and the 2D J spectrum results, the conformations of the two isomers were analysed. The six‐membered ring of the cis,trans isomer is flattened by 1,3‐diaxial interactions between two amino substituents; in the cis,cis isomer, ring pucker is increased owing to non‐bonded interaction between the equatorial amino groups and adjacent methylene protons. The 13 C and 15 N spin—lattice relaxation of the two isomeric 1,3,5‐triaminocyclohexanes was also measured at different pH values; NH x groups rotate faster with decreasing pH. Rotation/jump rates and barriers are reported, determined from the NT 1 DD ratios between 15 N and 13 C nuclei.