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

Abstract

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.

Synthesis, features and thermal decomposition of hexachlorostannates and hexachloroplatinates of tris(2,2′-dipyridyl)metal(II) and tris(1,10-phenanthroline)metal(II) (metal=Ru, Fe, Ni)

“…This means that the former ligand exhibits mainly a It-type donor character, whereas the latter also has an n-type donor character, n-Donors usually form more stable complexes, which implies that dipyridyl should have a better ability to form complexes than phenanthroline. The compounds examined in this work exhibit similar features to other complex salts containing [Mn(phen)3] 2+ or [M]I(dipy)3] 2+ that were studied earlier [14,15]. The present work extends our knowledge on this group of compounds and promotes an understanding of the role played by the ligand molecules in their stability and thermal reactivity.…”