An Expedition on Alkali and Alkaline-Earth Isocyanurate Hydrates: Structure Elucidation, Thermogravimetry, and Spectroscopy

Abstract

Several alkali and alkaline earth (iso)cyanurates were synthesized by simple aqueous acid-base reactions and aqueous salt metathesis reactions, respectively, yielding nine new structure types. Single-crystals could be grown and the crystal structures of Rb[H2C3N3O3]·H2O-I, Rb[H2C3N3O3]·H2O-II, Cs[H2C3N3O3]·0.5H2O, Sr[H2C3N3O3]2·4H2O, Ba3[H2C3N3O3]2[HC3N3O3]2·4H2O, Ca[HC3N3O3]·3.5H2O, Sr[HC3N3O3]·3H2O, Sr[HC3N3O3]·2H2O, and Sr2[C3N3O3]OH were elucidated by single-crystal XRD. Rb3[H2C3N3O3]3[H3C3N3O3]·4H2O, Cs[H2C3N3O3]·0.5H2O, and Sr[HC3N3O3]·2H2O were synthesized as phase pure, crystalline powders and were further characterized by powder XRD, FT-IR spectroscopy, UV/Vis spectroscopy, and thermogravimetry. Sr[HC3N3O3]·2H2O was shown to be an air- and water-resistant, cheap and easily obtained precursor for the phase-pure synthesis of Sr3[C3N3O3]2, a promising SHG material, and Sr[NCN]. Moreover, an interesting dependence of the polymeric anion structure from its protonation degree was observed.