A2TiF5·nH2O (A=K, Rb, or Cs; n=0 or 1): Synthesis, structure, characterization, and calculations of three new uni-dimensional titanium fluorides

Three new uni-dimensional alkali metal titanium fluoride materials, A2TiF5·nH2O (A=K, Rb, or Cs; n=0 or 1) have been synthesized by hydrothermal reactions. The structures of A2TiF5·nH2O have been determined by single-crystal X-ray diffraction. The Ti4+ cations have been reduced to Ti3+ during the synthesis reactions. All three A2TiF5·nH2O materials contain novel 1-D chain structures that are composed of the slightly distorted Ti3+F6 corner-sharing octahedra attributable to the Jahn–Teller distortion. The coordination environment of the alkali metal cations plays an important role to determine the degree of turning in the chain structures. Complete structural analyses, Infrared and UV–vis diffuse reflectance spectra, and thermal analyses are presented, as are electronic structure calculations.