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

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]center dot H2O-I, Rb[H2C3N3O3]center dot H2O-II, Cs[H2C3N3O3]center dot 0.5H(2)O, Sr[H2C3N3O3](2)center dot 4H(2)O, Ba-3[H2C3N3O3](2)[HC3N3O3](2)center dot 4H(2)O, Ca[HC3N3O3]center dot 3.5H(2)O, Sr[HC3N3O3]center dot 3H(2)O, Sr[HC3N3O3]center dot 2H(2)O, and Sr-2[C3N3O3]OH were elucidated by single-crystal XRD. Rb-3[H2C3N3O3](3)[H3C3N3O3]center dot 4H(2)O, Cs[H2C3N3O3]center dot 0.5H(2)O, and Sr[HC3N3O3]center dot 2H(2)O were synthesized as phase pure, crystalline powders and were further characterized by powder XRD, FT-IR spectroscopy, UV/Vis spectroscopy, and thermogravimetry. Sr[HC3N3O3]center dot 2H(2)O was shown to be an air- and water-resistant, cheap and easily obtained precursor for the phase-pure synthesis of Sr-3[C3N3O3]2, a promising SHG material, and Sr[NCN]. Moreover, an interesting dependence of the polymeric anion structure from its protonation degree was observed.