NMR Crystallography, Hydrogen Bonding and Optical Properties of the Novel 2D Hybrid Oxyfluorotitanate [H2taz]2·(Ti5O5F12)

The new 2D hybrid oxyfluorotitanate [H2taz]2·(Ti5O5F12), where [H2taz]+ represents 1,4-diH-1,2,4-triazolium cation ([C2N3H4]+), has been prepared, and its structure has been refined from powder X-ray diffraction data. It is built up from ∞(Ti5O5F12)2– inorganic layers separated by [H2taz]+ cations and adopts the same space group (Cmm2) and, considering the inorganic part, the same structure as [H2gua]2·(Ti5O5F12), where [H2gua]+ represents guanidinium cation ([C(NH2)3]+). The substitution of [H2gua]+ by [H2taz]+ was aimed at reduction of the refractive index, while a high optical band gap was maintained. The substitution effect is small, but [H2taz]2·(Ti5O5F12) could also allow a high UV protection with a good aesthetic effect. In [H2taz]2·(Ti5O5F12), a 50% site occupancy is attributed to one H atom site and two mirror symmetry related positions have a mixed C and N composition, preventing DFT calculations from being performed for the structural cell and preventing the cation configuration from being dete...