X-Ray crystal structure of a vinyllithium–tetrahydrofuran solvate (C 2 H 3 Li–thf) 4 . Quantitative estimation of Li–H distances by 6 Li– 1 H HOESY

Vinyllithium crystallizes with one equivalent of tetrahydrofuran (thf) and is tetrameric in the solid state whereas in thf solution a tetramer–dimer equilibrium (8: 1, 2.0 mol dm–3, –90 °C) is present; lithium–hydrogen distances in solution are derived quantitatively by 6Li–1H HOESY with ca. 0.2 Å accuracy.