Three Polyborates with High-Symmetry [B 12 O 24 ] Units Featuring Different Dimensions of Anion Groups.

Three polyborates, namely, LiNa 11 B 28 O 48 , Li 1.45 Na 7.55 B 21 O 36 , and Li 2 Na 4 Ca 7 Sr 2 B 13 O 27 F 9 , were synthesized via the high-temperature solution method. All of them feature high-symmetry [B 12 O 24 ] units, yet their anion groups exhibit distinct dimensions. LiNa 11 B 28 O 48 features a three-dimensional anionic structure of 3 [B 28 O 48 ] ∞ framework, which is composed of three units: [B 12 O 24 ], [B 15 O 30 ], and [BO 3 ]. Li 1.45 Na 7.55 B 21 O 36 possesses a one-dimensional anionic structure of 1 [B 21 O 36 ] ∞ chain consisting of [B 12 O 24 ] and [B 9 O 18 ] units. The anionic structure of Li 2 Na 4 Ca 7 Sr 2 B 13 O 27 F 9 is composed of two zero-dimensional isolated units, namely, [B 12 O 24 ] and [BO 3 ]. The novel FBBs [B 15 O 30 ] and [B 21 O 39 ] are present in LiNa 11 B 28 O 48 and Li 1.45 Na 7.55 B 21 O 36 , respectively. The anionic groups in these compounds exhibit a high degree of polymerization, thereby augmenting the structural diversity of borates. And the crystal structure, synthesis, thermal stability, and optical properties were meticulously discussed to guide the synthesis and characterization of novel polyborates.