Synthesis, vibrational and NMR spectroscopic characterization of [N(CH3)4][IO2F2] and X-ray crystal structure of [N(CH3)4]2[IO2F2][HF2]

The salt, [N(CH3)4][IO2F2], was prepared from [N(CH3)4][IO3] and 49% aqueous HF, and characterized by Raman, infrared, and 19F NMR spectroscopy. Crystals of [N(CH3)4]2[IO2F2][HF2] were obtained by reduction of [N(CH3)4][cis-IO2F4] in the presence of [N(CH3)4][F] in CH3CN solvent and were characterized by Raman spectroscopy and single-crystal X-ray diffraction: C2/m, a = 14.6765(2)Å, b = 8.60490(10)Å, c = 13.9572(2)Å, β = 120.2040(10)°, V = 1523.35(3)Å3, Z = 4 and R = 0.0192 at 210K. The crystal structure consists of two IO2F2− anions that are symmetrically bridged by two HF2− anions, forming a [F2O2I(FHF)2IO2F2]4− dimer. The symmetric bridging coordination for the HF2− anion in this structure represents a new bonding modality for the bifluoride anion.