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Untersucht wurde die thermische Zersetzung bei folgenden Komplexen: Ni(NCS)2(2, 4‐Me2Py)3 (I), (Me = Methyl, Py = Pyridin), Ni(NCS)2(2,5‐Me2Py)4 (II), Ni(NCS)2(2‐Me, 5‐ÄtPy)4 (III), (Ät = Äthyl), Ni(NCS)2(3,4‐Me2Py)4 (IV), and Ni(NCS)2(3,5‐Me2Py)4 (V). Bei Komplex I verläuft der Zersetzungsprozeß in 2 Stufen (−2, −1), bei den Komplexen II und III sind es ebenfalls 2 Stufen (−2, −2), bei Komplex IV 4 Stufen (−1, −1, −1, −1), während er bei Komplex V wiederum 2 Stufen (−2,5, −1,5) aufweist. Der primäre Faktor, der die stereochemischen Veränderungen bei Isothiocyanato‐Nickel(II)‐Komplexen mit Dialkylderivaten des Pyridins während der thermischen Zersetzungsreaktionen beeinflußt, ist der Alkylsubstituent in α‐Position am Pyridinring.

The reproducibility of the DTA curves of ammonium nitrate as functions of its grain size and the atmosphere during the measurements was studied with a derivatograph. The temperatures and the areas of the peaks assigned to the modification transitions IV --, III (peak 1), Ill -+ II (peak 2) and II --* I (peak 3) were evaluated. It was found that for some unground samples the area of peak 2 decreases markedly. It has been verified that in an atmosphere of moist air the temperature of peak 1 is lowered. The temperatures of lumpy and loose samples do not differ appreciably. Statistical methods evidenced the mutual dependence of the areas of peaks 1 and 2. The possible causes of this are discussed.

The paper deals with the chemical and physical factors influencing the stoichiometry of thermal decomposition of solid coordination compounds. Nickel(II) coordination compounds were used as examples : the problem of the relationship between the structure of the initial compound (and of its intermediates) and the stoichiometry of thermal decomposition is discussed; experimental conditions are shown to affect this decomposition, and the conceptions of the apparent and real stoichiometries of thermal decomposition are discussed. The results obtained may have a more general meaning.