Abstract:Nickel nitrate diammine, Ni(NH3)2(NO3)2, can be synthesised from the thermal decomposition of nickel nitrate hexammine, Ni[(NH3)6](NO3)2. The hexammine decomposes in two distinct major stages; the first releases 4 equivalents of ammonia while the second involves the release of NOx, N2, and H2O to yield NiO. The intermediate diammine compound can be isolated following the first deammoniation step or synthesised as a single phase from the hexammine under vacuum. Powder X-ray diffraction (PXD) experiments have allowed the structure of Ni(NH3)2(NO3)2 to be solved for the first time. The compound crystallises in orthorhombic space group Pca21 (a = 11.0628 (5) Å, b = 6.0454 (3) Å, c = 9.3526 (4) Å; Z = 4) and contains 11 non-hydrogen atoms in the asymmetric unit. Fourier transform infrared (FTIR) spectroscopy demonstrates that the bonding in the ammine is consistent with the structure determined by PXD.Keywords: crystal structure; ammine complex; structure determination; ammonia storage; vibrational spectroscopy
Hexaamminenickel chloride is the chemical compound with the formula [Ni(NH3)6]Cl2. It is the chloride salt of the metal ammine complex [Ni(NH3)6]2+. The cation features six ammonia (called ammines in coordination chemistry) ligands attached to the nickel(II) ion.
[Ni(NH3)6]2+, like all octahedral nickel(II) complexes, is paramagnetic with two unpaired electrons localized on each Ni center. [Ni(NH3)6]Cl2 is prepared by treating aqueous nickel(II) chloride with ammonia. It is useful as a molecular source of anhydrous nickel(II). 2b1af7f3a8