The thermal dissociation of sodium hexanitrocobaltate(III)

Abstract

The stoichiometry of the thermal decomposition reaction of Naz[Co(NO~)nl was studied by TG, DTA and mass spectrometric analysis.The thermal properties of NazKz[Co(NO2)6] 2 9 n H20 and Kz[Co(NOz)~] have been investigated by Duval and co-workers [1,2]. For the latter compound, a TG curve plateau was found from 43 ~ to 160 ~ which was said to be suitable for the automatic determination of cobalt. Above 160 ~ the evolution of 3 moles of NOz per mole of complex took place to give the mixture, CoO + 3KNOz. The same type of dissociation reaction was reported for Csz[Co(NO2)6] [3] and Naa[Co(NOz)6] [4]. Since the above data did not give very much information on the decomposition reaction stoichiometry or analysis of the reaction products, the thermal dissociation of Naz[Co(NOz)6] was studied in somewhat greater detail by TG, DTA and mass spectrometric analysis (MSA). Experimental Preparation of Na3CCo(NO~) 6]This complex was prepared by the method of Cunningham and Perkin [5] Analysis of the compound gave % metal oxide: 23.3% found, 23.69~ calc. nitrogen: 21.2% found, 20.79% calc. ApparatusThe thermobalance, DTA apparatus, and mass spectrometer have all been previously described [6]. The heating rate for the TG and DTA experiments was 10 ~ Results and discussionThe mass-loss and DTA curves of Naz[Co(NOz)6] and the MSA data are shown in Fig. 1.The mass-loss curve was rather surprising for two reasons: first, the initial complex was thermally stable up to about 200~ and, second, it did not dissociate

ТЕРМИЧЕСКОЕ РАЗЛОЖЕНИЕ КАТИОННЫХ, АНИОННЫХ И ДВОЙНЫХ КОМПЛЕКСНЫХ СОЕДИНЕНИЙ 3d-МЕТАЛЛОВ

“…Для анализа твердой фазы [80] использованы рентгенодифракционный и мессбауэровский методы анализа, а для анализа газовых продуктов -газовая хроматография. В работе [81] Помимо публикаций, посвященных цианокомплексам, были найдены работы по изучению термолиза оксалатных комплексов [29,[101][102][103][104][105][106][107], гексанитрокобальтата [108,109] и роданидного комплекса [110]. Согласно [29], термическая устойчивость К 3 [М(Ox) 3 ]•nH 2 O зависит от природы М следующим образом: Cr > Fe,Co, хотя константа устойчивости комплекса Со значительно выше, чем железа.…”

“…Термическая диссоциация гексанитрокобальтатов описана в работах [108,109] как и в случае катионных соединений. В инертной среде процесс разложения значительно усложняется: наблюдается образование карбидов ц.и., оксалатов и карбонатов и значительных количеств свободного углерода.…”