Evolution of Guanazolium Fluoroaluminates within the Composition-Space Diagram and with the Temperature

• Published in: Crystal growth & design 2010-12, Vol.10 (12), p.5159-5168
• Main Authors: Cadiau, Amandine, Bail, Armel Le, Hémon-Ribaud, Annie, Leblanc, Marc, Body, Monique, Fayon, Franck, Durand, Etienne, Boulou, Jean-Claude, Maisonneuve, Vincent
• Format: Article
• Language: English
• Subjects: Chemical Sciences; Condensed matter: structure, mechanical and thermal properties; Cross-disciplinary physics: materials science; rheology; Exact sciences and technology; Material chemistry; Materials science; Materials synthesis; materials processing; Organic compounds; Physics; Structure of solids and liquids; crystallography; Structure of specific crystalline solids
• ISSN: 1528-7483; 1528-7505
• DOI: 10.1021/cg100909x

The 2D composition-space diagram of the Al(OH)3−Am 2 TAZ−HFaq−ethanol system is established under microwave heating at 190 °C for [Al3+] = 1 mol·L−1. Four new fluoroaluminates are evidenced when the [HF]/[Am 2 TAZ] ratio is increased in the starting solution, and the dimensionality of the inorganic frameworks is increased from 0D in [HAm 2 TAZ]2·(AlF5(H2O))·2H2O (Pc, Z = 2), to 1D in [HAm 2 TAZ]2·(AlF5) and [HAm 2 TAZ]2·(Al2F8) (Fdd2, Z = 8), and to 2D in [HAm 2 TAZ]2·(Al5F17) (Imm2, Z = 2). This evolution is partially paralleled by the thermal decomposition of [HAm 2 TAZ]2·(AlF5(H2O))·2H2O; on heating, this hydrate gives [HAm 2 TAZ]2·(AlF5) at 100−150 °C and [HAm 2 TAZ]2·(Al2F8) at 180 °C; the loss and simultaneous decomposition of [HAm 2 TAZ]F leave a solid residue of polymeric paracyanogen (CN)2n that is further decomposed and hydrolyzed into HCN and HNCO by atmospheric water traces. NMR 19F spectroscopy of [HAm 2 TAZ]2·(AlF5) is in agreement with the crystallographic determination, and the 27Al spectrum demonstrates that a significant F−/OH− substitution is excluded.