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Solution and Solid‐State Preparation of 18‐Crown[6] Complexes with M[HSO 4 ] n Salts (M = NH 4 + , K + , Sr 2+ and n = 1, 2) and an Investigation of Solvation/Desolvation Processes and Crystal Polymorphism
Author(s) -
Braga Dario,
Gandolfi Massimo,
Lusi Matteo,
Paolucci Demis,
Polito Marco,
Rubini Katia,
Grepioni Fabrizia
Publication year - 2007
Publication title -
chemistry – a european journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.687
H-Index - 242
eISSN - 1521-3765
pISSN - 0947-6539
DOI - 10.1002/chem.200601850
Subject(s) - chemistry , differential scanning calorimetry , crystallography , crown ether , x ray crystallography , 18 crown 6 , thermogravimetric analysis , molecule , diffraction , organic chemistry , ion , physics , optics , thermodynamics
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.