Proton magnetic resonance studies of cyclic compounds. Part X. The spectrum and conformation of trans-decahydroquinoline co-ordinated to tris(dipivaloylmethanato)europium

Abstract

The ¹H n.m.r. spectrum of trans-decahydroquinoline, simplified to a near-first-order situation by the addition of tris(dipivaloylmethanato)europium, is in complete agreement with a twin-chair conformation for the molecule, and decoupling experiments allowed confident assignment of every signal. Graphs of induced shifts, for each proton, plotted against the molar ratio of Eu(dpm)₃ to trans-decahydroquinoline, were linear only up to a ratio of ca. 0·3. A full quantitative treatment yielded a value of 12 I mol^–1 for the equilibrium (or binding) constant, at 31 °C, in the reaction of the base with the lanthanide.