Synthesis and crystal structure of a novel potassium borate with an unprecedented [B12O16(OH)(8)](4-) anion

A novel potassium borate, KB3O4(OH)(2), has been hydrothermally synthesized and structurally characterized by single crystal X-ray diffraction, FTIR and thermogravimetric analysis. The compound crystallizes in the tetragonal system, space group P4/ncc (No. 130), a = 11.3482(3) angstrom, b = 11.3482(3) angstrom, c = 15.9169(6) angstrom, V = 2049.8(2) A(3), and Z = 16. The structure consists of an unprecedented unit of [B12O16(OH)(8)](4-) anion with an 8-membered borate ring constructed by vertex-sharing of four [B3O4(OH)(2)](-) clusters. The [B12O16(OH)(8)](4-) units are linked together by hydrogen bonds to form a sheet-like structure, which is further interconnected via ionic K-O bonds to generate a 3D structure with two types of ID channels along the c-axis.