A new class of flexible energetic salts, part 4: The crystal structures of hexaaquomagnesium(II), hexaaquomanganese(II), and hexaaquozinc(II) dihydrate salts of dinitramide

The crystal structures of the hexaaquomagnesium (1), hexaaquomanganese (2), and hexaaquozinc (3) dihydrate salts of dinitramide have been determined. 1 crystallizes in the monoclinic space group P2₁/n with cell dimensions a = 9.589(2), b = 7.420(1), c = 11.116(2) Å, = 108.25(3)°, 2 crystallizes in the monoclinic space group P2₁/n with cell dimensions a = 9.623(4), b = 7.477(2), c = 11.274(3) Å, = 108.38(3)°, and 3 crystallizes in the monoclinic space group P2₁/n with cell dimensions a = 9.513(1), b = 7.4270(8), c = 11.164(1) Å, = 108.806(6)°. The three structures are isostructural, consisting of hexaaquo cations, dinitramide anions and water molecules interlinked by an extensive three dimensional hydrogen bonding interactions. All oxygen atoms as well as the central nitrogen atom of the dinitramide anion are involved in acceptor hydrogen bonds with neighboring water protons. As a consequence of the constraints imposed by these hydrogen bonds the dinitramide ions are almost planar with average deviations of 0.01 Å for 1, 0.03 Å for 2 and 0.03 Å for 3.