STRUCTURE OF LITHIUM CATENA-POLY[3,4-DIHYDROXOPENTABORATE-1 5-MU-OXO]/

LiH2B5O9, M(r) = 207.0, monoclinic, P2(1)/a, a = 13.576 (4), b = 9.077 (4), c = 5.543 (3) angstrom, beta = 91.47 (1)degrees, V = 682.8 (4)) angstrom3, Z = 4, D(x) = 2.013 g cm-3, lambda(Mo Kalpha) = 0.7107 angs trom, mu = 2.06 cm F(000) = 408, T = 293 K, R = 0.049 for 1689 indepen dent observed reflections. The structure contains chains of [B5O9H2]- anions linked through shared O atoms. In each anionic unit two B3O3 ri ngs, each incorporating two triangular BO3 units, are connected by a s hared tetrahedral BO4 unit. The Li atom has four O-atom neighbours arr anged in an approximately tetrahedral configuration. The Li polyhedra connect B-O polyanions to form a two-dimensional network. Further conn ections are provided by hydrogen bonds.