Natural‐abundance lithium‐6 NMR spin–lattice relaxation in some simple organolithium compounds

6 Li, 7 Li and 13 C spin–lattice relaxation and NOE data are reported for methyllithium, butyllithium and phenyllithium with 6 Li T 1 values found in the order of tens of seconds and their relaxation 2–3 orders of magnitude less efficient than that for 7 Li. The data indicate that 6 Li is substantially relaxed by the intramolecular 6 Li– 1 H mechanism, whereas both quadrupolar and 6 Li– 7 Li dipolar relaxation are minor processes. The non‐linearity of the Arrhenius curve for Me 6 Li is compatible with a small spin–rotation contribution. Since 6 Li 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 7 Li NMR.