Sn[B2O3F2]-The First Tin Fluorooxoborate as Possible NLO Material

Herein, the crystal structure as well as second-harmonic-generation (SHG), thermal and spectroscopic properties of Sn[B2O3F2] (TFB = tin-fluorooxo-borate) are presented. TFB adopts a novel non-centrosymmetric crystal structure, which is determined by single-crystal X-ray diffraction (XRD) (P31m, Z = 1, a = 4.5072(2) angstrom, c = 4.7624(3) angstrom) and comprises [B2O3F2](2-) layers consisting solely of BO3F tetrahedra; the covalent B-F bonds are unequivocally localized via solid-state NMR spectroscopy as well as density functional theory (DFT) calculations. TFB is insensitive to air and moisture, shows a stronger SHG intensity than K[H2PO4] (KDP) and a bandgap of approximate to 5 eV. The thermal decomposition yields two new borate fluorides.