Synthesis and Crystal Structure of a Novel Potassium Borate with an Unprecedented [B 12 O 16 (OH) 8 ] 4− Anion

A novel potassium borate, KB 3 O 4 (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 P 4/ ncc (No. 130), a = 11.3482(3) Å, b = 11.3482(3) Å, c = 15.9169(6) Å, V = 2049.8(2) Å 3 , and Z = 16. The structure consists of an unprecedented unit of [B 12 O 16 (OH) 8 ] 4− anion with an 8‐membered borate ring constructed by vertex‐sharing of four [B 3 O 4 (OH) 2 ] − clusters. The [B 12 O 16 (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 1D channels along the c ‐axis.