Abstract
A number of ruthenium (III) ammine complexes containing phosphate or oxalate groups have been prepared from previously known ruthenium (III) ammine compounds. In both cases only one oxyacid group could be introduced into the co-ordination sphere; and the complexes thus formed are the phosphato tetrammine ruthenium (III) and the oxalato tetrammine ruthenium (III) ion. All the other compounds prepared contain the phosphate and oxalate group in the ionised form. Attempts to prepare phosphato-and oxalato-pentammines have failed, indicating that both groups form stable complexes only - in the case of ruthenium ammines - when they act as bidentate ligands. The five-membered chelate ring formed between the metal and oxalate group was more easily formed and more stable than the four-membered phosphate - metal ring. In connection with the above study it was necessary to investigate the various forms of ruthenium (III) chlorides, namely "commercial" -hydrated- and anhydrous-ruthenium (III) chlorides. Evidence has been found for the presence of both positively and negatively charged species, containing ruthenium, in aqueous solutions of commercial ruthenium chloride and hydrated ruthenium (III) chloride. The nature of these species has been determined by ion exchange methods. It is concluded from the evidence presented that the "commercial" ruthenium chloride which was previously known to contain a nitrosyl group probably has structure of the type [RuCl(H[2]O)[3]][Ru(NO)Cl[5]]. Possible structures have been proposed for the hydrated- and anhydrous-ruthenium (III) chlorides in the solid state. Complex formation between ruthenium (III) and phosphoric acid has been investigated and ion exchange methods have shown the presence of both cationic and anionic complex phosphates of ruthenium (III). The existence of mixed chloro-phosphato ruthenium complexes has been also indicated. Possible structures for the complex phosphates have been suggested.