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Updated: Dec 3, 2025

Syntheses, Crystallization, and Spectroscopic Characterization of 3,5-Lutidine N-Oxide Dehydrate
Published on: April 24, 2018
A curious case of dynamic disorder in pyrrolidine rings elucidated by NMR crystallography
Patrick M J Szell1, Steven P Brown, Leslie P Hughes
1Department of Physics, University of Warwick, Coventry, CV4 7AL, UK. Patrick.Szell@warwick.ac.uk S.P.Brown@warwick.ac.uk.
Abstract:
A pharmaceutical exhibits differing dynamics in crystallographically distinct pyrrolidine rings despite being nearly related by symmetry, with one performing ring inversions while the other is constrained to torsional librations. Using 13C solid-state magic-angle spinning (MAS) NMR and DFT calculations, we show that this contrast originates from C-HH-C close contacts and less efficient C-Hπ intermolecular interactions observed in the transition state of the constrained pyrrolidine ring, highlighting the influence of the crystallographic environment on the molecular motion.
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