Na3B3O3F6: Synthesis, Crystal Structure, and Ionic Conductivity

Crystalline Na3B3O3F6 was synthesized from H3BO3 and NaBF4 at 623 K, alternatively NaBO2 can be reacted with NaBF4 at 673 K. The title compound (C2/c, a = 11.866(7), b = 6.901(4), c = 9.367(6) angstrom, beta = 113.724(9)degrees) contains the cyclo-fluorooxotriborate anion B3O3F63, which displays a planar B3O3 ring. Within the margins of experimental error, its point group symmetry is D3h. Layers of fluorinated boroxine rings and sodium atoms are stacked in an alternating manner in parallel to the ab plane. The novel sodium fluorooxoborate is a poor sodium ion conductor with conductivities of 8.7?X?105 and 3.6?X?103 S.cm1 at 523 and 623 K, respectively.