The Lithium Fluoride Tetrafluoroborate Li2F[BF4]

Abstract Colorless Li 2 BF 5 (better: Li 2 F[BF 4 ]) was obtained by partial decomposition of Li[BF 4 ] in a closed silica ampoule. It crystallizes in the tetragonal space group I 4 1 / amd with the lattice parameters a = 512.8(2) pm and c = 1326.6(4) pm ( c / a = 2.587). Lithium is sixfold and boron fourfold coordinated by fluorine at distances of about 210 pm (6 ×) and 139 pm (4 ×), respectively. A cristobalite ‐type cationic framework 3D‐{[(F1)Li 4/2 ] + } of vertex‐sharing [(F1)Li 4 ] 3+ tetrahedra embeds the isolated tetrahedral [B(F2) 4 ] – anions.