Crystal structure of hexamethylguanidinium hexafluorosilicate hexahydrate

Single crystals of the hexamethylguanidinium hexafluorosilicate hexahydrate salt, [C(NMe2)(3)(+)](2)SiF62-. 6H(2)O, were isolated when a product, obta ined by water removal from aqueous [C(NMe2)(3)]F ina glass vessel, was recr ystallized from CH3OH. The crystal structure of this salt was determined, a nd the geometry of the free hexamethylguanidinium cation was calculated, sh owing that its observed propeller-shaped arrangement is not caused by solid state effects but is the true minimum energy structure of the free ion. (C ) 1999 Elsevier Science S.A. All rights reserved.