Synthesis and characterization of the first hydrothermally synthesized tin borate Sn2B3O6(OH)

In the system Sn-B-O-H, the first tin borate Sn2B3O6(OH) was successfully synthesized by a simple hydrothermal process. The compound crystallizes in the centrosymmetric monoclinic space group P21/n (no. 14) with the lattice parameters a = 443.5(2), b = 1102.5(4), c = 1396.4(5) pm, and β = 95.31(1)° (Z = 4). Structurally, Sn2B3O6(OH) features infinite chains of B3O8 groups connected along the a axis. The Sn2+ cations are arranged in form of layers between the anionic borate chains. Interestingly, Sn2B3O6(OH) is the first example of a hydrothermally synthesized tin borate, in which adjacent anionic borate chains are further connected by O–H···O hydrogen bond interactions into a three-dimensional structure. The characterization of Sn2B3O6(OH) is based on single-crystal X-ray diffraction data, vibrational spectroscopy, DFT calculations, and thermoanalytical investigations.