Anhydrous aluminium nitrate, and the nitronium and alkylammonium tetranitratoaluminates
Abstract
Conditions are described under which reaction of the 9-hydrate of aluminium nitrate with excess of dinitrogen pentoxide gives the 1 : 1 adduct Al(NO3)3,N2O5. The anhydrous nitrate can be obtained from this adduct by sublimation in a vacuum. The pentoxide bonds tenaciously to aluminium nitrate, and compounds Al(NO3)3,xN2O5(where O < x < 1) are usually the initial products. Reaction of aluminium bromide with chlorine nitrate, followed by sublimation, gave Al(NO3)3,0·4N2O5. The infrared spectrum of the 1 : 1 adduct identifies it as the salt (NO2+)[Al(NO3)4]–. This, and the salt (Et4N)[Al(NO3)4], are the first substantiated examples of the [Al(NO3)4]– ion. For the tetraethylammonium salt the infrared spectrum, the ultraviolet spectrum of solutions in acetonitrile, and the electrical conductivity of solutions in nitromethane are discussed.