Structures of Classical Reagents in Chemical Synthesis: ( n BuLi) 6 , ( t BuLi) 4 , and the Metastable ( t BuLi · Et 2 O) 2

Crystalline n BuLi is also hexameric; this same degree of oligomerization was determined years ago in solutions of hydrocarbons. Six Li atoms form a distorted octahedron, six of whose triangular faces are capped by n Bu groups (see structure depicted). The unusual arrangement of the β‐C atoms indicates interactions with the Li atoms. In contrast, t BuLi forms a T d ‐symmetric tetramer in the solid state.