K. Harmon, G. F. Avci, J. Harmon
Aug 1, 1987
Citations
0
Influential Citations
15
Citations
Journal
Journal of Molecular Structure
Abstract
Abstract Tetramethylammonium fluoride trihydrate and tetrahydrate are framework clathrate hydrates that form at 0°C; once formed these hydrates remain as stable, crystalline solids at 25°C. However, stoichiometric 4:1 and 3:1 mixtures of water and tetramethylammonium fluoride, whether prepared by evaporation of water from aqueous solution or by addition of water to pre-formed monohydrate, never crystallize at 25°C without external nucleation. Elucidation of the solid—liquid relationships of these two hydrates explains the confusing observations made in earlier preparations of the monohydrate and dihydrate. At 25°C the first solid formed on dehydration is the dihydrate which is in equilibrium with stoichiometric liquid trihydrate; the same dihydrate is obtained by dehydration of solid trihydrate. A structure is proposed for the solid trihydrate based on analogy with the recently published structure of tetraethylammonium fluoride·2.75 H2O and on infrared spectral comparison with this latter compound. Structural considerations of the monohydrate and dihydrate are also discussed.