Thermal reactions of lead(iv) chloride complexes in the solid state

et al. 1987

The thermal decompositions of [Co(py)4Clz]2PbCl 6 and [Ru(dipy)3]PbCl 6 were examined by dynamic thermoanalytical methods and under isothermal conditions permitting quantitative determination of some of the reaction products. A comparative study of the corresponding chloride salts was also performed. Both groups of compounds decompose with the liberation of chlorine and organic ligands (and H~O in the case of the hydrates of the chlorides), and the process is accompanied by the simultaneous transitions Pb(4+)---,Pb(2+) and Co(3+) --,Co(2 + ). The ruthenium complex salts initially decompose without a change in the oxidation state of the Ru atom, but upon thermal treatment of the hexachloroplumbate certain chlorination products of the organic ligands are formed.Hexachloroplumbic acid (H2PbC16) forms a large group of salt-like derivatives with numerous nitrogen-containing organic bases [1]. Among the hexachloroplumbates of metals, only the existence of the salts of potassium, rubidium and caesium has so far been proved. Several compounds of H2PbC16 with monoand divalent complex cations are also known [1]. Investigations of the thermal properties and thermochemistry of hexachloroplumbic acid derivatives were conducted earlier in this laboratory on the hexachloroplumbates of alkali metals [2] and numerous nitrogen-containing bases [3,4]. The present communication reports the results of an analogous study of two hexachloroplumbates of complex cations [Co(py),C12)2]PbCl 6 and the newly synthesized [Ru(dipy)a]PbC16, as well as the corresponding chloride salts.

Section: Resultsmentioning

confidence: 99%

mentioning

confidence: 99%

Thermal decompositions of [Co(py)4Cl2]2PbCl6 and [Ru(dipy)3]PbCl6

Szychlinski

Łubkowski

et al. 1987

“…Subsequently, the enthalpies of formation of crystalline iodides and the energies of the crystal lattice of the salts were evaluated on the basis of the thermochemical cycle [1][2][3]. The necessary thermochemical data for these estimations have been taken from the literature [6,7]. This procedure could not be applied to N, N, N-triethyl-ethanaminium iodide since the dissociation of the compound requires the overcoming of a noticeable activation barrier.…”

Section: Resultsmentioning

confidence: 99%

“…This procedure could not be applied to N, N, N-triethyl-ethanaminium iodide since the dissociation of the compound requires the overcoming of a noticeable activation barrier. The crystal lattice energies were also estimated from the Kapustinskii-Yatsimirskii formula [11,12] using values of "thermochemical" radii of the anion [6] and cations [1,7] from literature. The derived thermochemical characteristics together with some literature data are listed in Table 1.…”

Section: Resultsmentioning

confidence: 99%

Thermal behaviour and thermochemistry of ethanaminium iodides

Dokurno

Łubkowski

1990

Dynamic thermoanalytical methods (DTA, TG, DTG) have been applied to the investigation of the thermal features of compounds of general formula (EtnNHa-n)I, with n = 0-4. The primary decomposition step of these derivatives is accompanied by the release of amine and HI to the gaseous phase. The enthalpies of this process have been evaluated on the basis of the van't Hoff equation and analytical TG curves. Values thus derived together with the available literature data were used to estimate the enthalpies of formation and the energies of the crystal lattice of the compounds. Further information regarding this latter quantity was also drawn from the Kapustinskii-Yatsimirskii formula.Owing to the rather strong base character of alkanamines they form salttype compounds with typical inorganic acids. The halogenide salts of such amines are one of the simplest ionic derivatives of organic compounds. Such derivatives are, thus very convenient model systems for studying the influence of the structure of cations on the features of parent molecules. In our previous note we turned our attention to the thermochemistry and thermal properties of numerous chloride salts of nitrogen organic bases [1][2][3]. The present note is devoted to similar studies for ammonium and ethanaminium iodides. Salts of alkanamines appear to have some industrial applications [4][5]. Nitrogen organic bases also commonly appear in biological systems. Thus, the present studies are of considerable scientific and practical importance.Experimental N, N, N-triethyl-ethanaminium iodide was purchased from Fluka AG and Bush SG. Other compounds studied were synthesized by mixing an aqueous solution of appropriate bases with an almost stoichiometric amount of hydroiodic acid. The resulting crystals were separated and purified by John Wiley & Sons, Limited, Chichester Akad~tiai Kiad6, Budapest

Thermodynamics of phase transitions and heat capacities of monosubstituted n-alkanaminium bromides above room temperature

Generowicz¹,

Lubkowski

1990

POLANDDifferential scanning calorimetry was applied to examine the thermodynamics of solidstate phase transitions and fusion processes of compounds of the general formula (nCpHzp+INH3)Br (where p = 0-3). The heat capacities of the compounds in the range from ambient temperature to the onset of their volatilization were also studied. All the thermochemical characteristics reveal a dependence on the structure of the alkanaminium cations.In several earlier papers, we have reported the results of studies on the thermal features of various salts of nitrogen organic bases [1][2][3][4][5]. On the basis of these investigations, we were able to derive basic thermochemical quantities for the pure compounds, i.e. their standard enthalpies of formation and crystal lattice energies, as well as those characterizing their decomposition. Unfortunately, the applied method appeared to be insufficient for quantitative examination of the thermal behaviour of the compounds below the onset of their dissociation and volatilization. This note reports the results of differential scanning calorimetry determinations of heat capacities and enthalpies of solid-state phase transitions and melting for selected nalkanaminium bromides. Despite the investigations undertaken in the past, the knowledge of the latter problems is still incomplete [6][7][8][9][10][11][12][13].