New iron(III) nitrate hydrates: Fe(NO3)3·xH2O with x = 4, 5 and 6

Abstract

Crystals of the title compounds were grown from their hydrous melts or solutions. The crystal structure of iron(III) trinitrate hexahydrate {hexaaquairon(III) trinitrate, [Fe(H(2)O)(6)](NO(3))(3)} is built up from [Fe(H(2)O)(6)](2+) octahedra and nitrate anions connected via hydrogen bonds. In iron(III) trinitrate pentahydrate {pentaaquanitratoiron(III) dinitrate, [Fe(NO(3))(H(2)O)(5)](NO(3))(2)}, one water molecule in the coordination octahedron of the Fe(III) atom is substituted by an O atom of a nitrate group. Iron(III) trinitrate tetrahydrate {triaquadinitratoiron(III) nitrate monohydrate, [Fe(NO(3))(2)(H(2)O)(3)]NO(3)·H(2)O} represents the first example of a simple iron(III) nitrate with pentagonal-bipyramidal coordination geometry, where two bidentate nitrate anions and one water molecule form a pentagonal plane.