The rigid polycyclic nitrogen compound was considered as a test for the reliability of internuclear distances calculated by1H-NMR spin-lattice relaxation rates. The ‘isotropic’ motional correlation time was calculated from13C relaxation rates (τC= 0.11 ns at 298 K). Dipolar cross-relaxation rates were calculated by measuring non-, mono- and double-selective proton spin-lattice relaxation rates. All the experimental relaxation rates were thoroughly accounted for by dipolar pairwise interactions. Only at high temperatures a certain contribution from the spin rotational mechanism was apparent.