Li2 BaSc(BO3 )2 F and LiBa2 Pb(BO3 )2 F with Layered Structures featuring Special Li-O/F Configurations.

Abstract

Two new borate fluorides, Li2 BaSc(BO3 )2 F and LiBa2 Pb(BO3 )2 F, with layered structures featuring special Li-O/F configurations have been successfully prepared by the high-temperature solution method. Li2 BaSc(BO3 )2 F contains the first reported 2 ∞ [Li2 (BO3 )2 F] double layers that are evolved from 2 ∞ [Be2 BO3 F2 ] single layers in KBe2 BO3 F2 through substituting BeO4 with the LiO3 F tetrahedra. The adjacent double layers are tightly connected by strong Sc-O bonds, generating the strongest interlayer bond and smallest interlayer distance among KBe2 BO3 F2 derivatives with double-layered structures. LiBa2 Pb(BO3 )2 F features 2 ∞ [Li(BO3 )2 F] single layers built up of special LiO4 F2 octahedra and the BO3 triangles. To our best knowledge, the LiO4 F2 octahedron is observed for the first time in borates. Besides, the LiO4 F2 octahedra construct unique 1 ∞ [LiO4 F] straight chains through sharing apical F atoms, which is different from the configurations of the similar six-coordinated LiO6 octahedra in other borates.