A study of the thermal oxidation-reduction of some ammine complexes of metal nitrates



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A study has been made of the oxidation-reduction reactions that can be thermally induced in ammine complexes of metal nitrates. Thermogravimetric analysis, differential thermal analysis, mass spectrometric analysis, infrared spectroscopy, reflectance spectroscopy, and X-ray spectroscopy, as well as conventional chemical analysis were used to investigate these complexes and their resulting dissociation products. The complexes studied in the investigation were of the type M(Am)[lowered n](NO[lowered 3)[lowered 2] where M = copper(II) ion, nickel(II) ion, or cobalt(III) ion. Am = ammonia, methylamine, ethylamine, isopropylamine, or ethylenediamine, and n = 2, 3, 4, or 6. The thermal oxidation-reductions were found to occur in the 200[degrees] to 300[degrees]C temperature range and the rates of these reactions were very fast, sometimes resulting in explosion. The products from reactions were dependent upon the amine used as ligands in the complex. In all cases water, the amine used, nitrogen, and nitrogen(I) oxide were found as products of the reaction, but the other products, the alcohol and alkene, were dependent upon the starting amine. It was also observed that nitrogen(IV) oxide was a product of the reaction when the complex was heated in a flowing inert atmosphere, but when the complex was heated in a closed system with an inert atmosphere, the dissociation products contained very little nitrogen(IV) oxide. Studies were made of the ammine complexes of copper(II) nitrate and nickel(II) nitrate using labeling in the nitrate ion. From the resulting data, probable mechanisms are discussed.