Stereodynamics of inversion and rotation in trialkylamines. N,N-Diisopropyl primary alkylamines studied by dynamic NMR spectroscopy and molecular mechanics calculations

From the temperature dependence of NMR spectra, two separate conformational processes can be distinguished and studied in N,N-diisopropylneopentylamine. A high-barrier inversion/rotation process involves eclipsing of t-butyl and isopropyl groups, while a rotation process with a lower barrier involves lesser eclipsing interactions. Molecular mechanics calculations help illustrate the ground state conformations involved. Barriers are smaller when the neopentyl group is replaced by less branched primary alkyl groups.