Lithium perbromate monohydrate at 296 and 173 K.

Lithium tetraoxobromate(1-) monohydrate, LiBrO4.-H2O, whose perchlorate analog has not yet been described, is found to be isomorphic with NaBrO4.H2O and NaClO4.H2O. Each of the two inequivalent Li ions is coordinated by six O atoms, thus forming distorted octahedra, each of which has three inequivalent Li-O distances. At room temperature, the average Li(1)-O and Li(2)-O distances are 2.150 and 2.164 A, respectively. The perbromate ion displays very nearly regular tetrahedral geometry, although it is not subject to symmetry constraints. At 296 K the average observed Br-O distance is 1.610 (4) A and the average O-Br-O angle is 109.5 (6) degrees, while at 173 K the corresponding values are 1.613 (4) A and 109.5 (7) degrees. The perbromate ion shows rigid-body behavior but the lithium coordination polyhedra do not. At 296 K, the average rigid-body corrected Br-O distance in the perbromate ion is 1.624 (3) A, in excellent agreement with the corresponding value reported for NaBrO4.H2O. Refinement of the two inequivalent H atoms allowed detailed analysis of the hydrogen bonding, which is more extensive than in NaBrO4.H2O or in NaClO4.H2O. The average observed B values for the H atoms [2.9 (3) A2 at 296 K and 2.8 (3) A2 at 173 K] are sufficiently small to suggest that dynamic disordering of the H atoms (determined by magnetic resonance methods for NaClO4.H2O) is not significant in the title salt.