Crystal structures of ordered and plastic-crystalline phases of iso-butyllithium by X-ray powder diffraction

Donor-unsupported iso-butyllithium consists of hexamers with an ordered triclinic structure at −80 °C (α-phase). At ambient temperature, the compound exists as an orthorhombic, remarkably stable, plastic-crystalline γ-phase, which is built by disordered hexamers adopting a distorted face-centred cubic packing. Both structures were determined by X-ray powder diffraction. Additionally, an intermediate β-phase is observed.