Solution and Solid-State Preparation of 18-Crown[6] Complexes with M[HSO4]n Salts (M = NH4+, K+, Sr2+ and n = 1, 2) and an Investigation of Solvation/Desolvation Processes and Crystal Polymorphism

✍ Scribed by Dario Braga; Massimo Gandolfi; Matteo Lusi; Demis Paolucci; Marco Polito; Katia Rubini; Fabrizia Grepioni

• Publisher: John Wiley and Sons
• Year: 2007
• Tongue: English
• Weight: 313 KB
• Volume: 13
• Category: Article
• ISSN: 0947-6539
• DOI: 10.1002/chem.200601850

✦ Synopsis

Abstract

18‐Crown[6] ether has been used to prepare a new class of organic–inorganic complexes of general formula 18‐crown[6]⋅M[HSO~4~]~n~ (where M = NH~4~^+^, K^+^, Sr^2+^ and n = 1, 2) by reacting directly in solution or in the solid state the crown ether 18‐crown[6] with inorganic salts such as [NH~4~][HSO~4~], K[HSO~4~], and Sr[HSO~4~]~2~. The structures of 18‐crown[6]⋅[NH~4~][HSO~4~]⋅2 H~2~O (1⋅2 H~2~O), 18‐crown[6]⋅[NH~4~][HSO~4~] (1), 18‐crown[6]⋅K[HSO~4~]⋅2 H~2~O (2⋅2 H~2~O), 18‐crown[6]⋅K[HSO~4~] (2), and 18‐crown[6]⋅Sr[HSO~4~]~2~ (3) have been characterized by single‐crystal X‐ray diffraction. The reversible water loss in compounds 1⋅2 H~2~O and 2⋅2 H~2~O leads to formation of the corresponding anhydrous phases 18‐crown[6]⋅[NH~4~][HSO~4~] (1), and 18‐crown[6]⋅K[HSO~4~] (2), which undergo, on further heating, enantiotropic solid‐solid transitions very likely associated with the on‐set of a solid state dynamical process. Similar high‐temperature behavior is shown by 18‐crown[6]⋅Sr[HSO~4~]~2~ (3). The dehydration and phase‐transition processes have been investigated by differential scanning calorimetry (DSC), thermogravimetric analysis (TGA) and variable temperature X‐ray powder diffraction.