NATURAL-ABUNDANCE LI-6 NMR SPIN-LATTICE RELAXATION IN SOME SIMPLE ORGANOLITHIUM COMPOUNDS

6Li, 7Li and 13C spin–lattice relaxation and NOE data are reported for methyllithium, butyllithium and phenyllithium with 6Li T1 values found in the order of tens of seconds and their relaxation 2–3 orders of magnitude less efficient than that for 7Li. The data indicate that 6Li is substantially relaxed by the intramolecular 6Li–1H mechanism, whereas both quadrupolar and 6Li–7Li dipolar relaxation are minor processes. The non‐linearity of the Arrhenius curve for Me6Li is compatible with a small spin–rotation contribution. Since 6Li in solution behaves essentially as a spin‐1/2 nucleus, it represents, in spite of its lower magnetic moment and overall sensitivity, an attractive alternative to 7Li NMR. Copyright © 1978 Heyden & Son Ltd.