Platinum Metals Rev., 1964, 8, (3), 106
Ethylenediamine Complexes of Ruthenium
So far as is known, no ethylenediamine complexes of ruthenium have been isolated. The reaction between ethylenediamine and chloro complexes of ruthenium such as ammonium chlororuthenite or ruthenium trichloride results in the formation of dark brown viscous solutions from which it seems impossible to separate any crystalline derivatives. A technique earlier discovered and used to prepare ammino derivatives of ruthenium II has now been successfully used to produce an ethylenediamine complex of ruthenium II, [en3Ru],ZnCl4. This compound should provide a suitable starting-point for the preparation of other ethylene-diamine complexes, particularly of ruthenium III since in its reactions it appears to be analogous to the ammino complex [(NH3)6Ru], ZnCl4.
In a Ph.D. Thesis (London University, 1955) Lever, and at the International Conference on Co-ordination Chemistry, London, 1959 (Special Publication of the Chemical Society, No. 13, 1959, 135-136) Lever and Powell described the preparation of hexamminoruthenium dichloride, [(NH3)6Ru]Cl2 and the chlorozincate [(NH3)6Ru],ZnCl4 by the reduction of ruthenium chloro complexes with zinc dust in ammoniacal ammonium chloride solution. It has now been shown that by cautiously adding zinc dust to a solution of ruthenium trichloride in 25 per cent ethylenediamine, boiling under reflux, filtering, cooling, and carefully acidifying the solution to pH 1-2 crystals of [en3Ru],ZnCl4 can be separated. (Found Ru 20.55, Zn 13.37, N 17.22, C1 29.10, C 14.93, H 4.93 per cent; [en3Ru],ZnCl4 requires Ru 20.69, Zn 13.39, N 17.21, CI 29.02, C 14.75, H 4.95 per cent).
It has, so far, not been possible to investigate fully the reactions of this compound but it has been found to behave similarly to the analogous ammino complex. Thus, when it is boiled with hydrochloric acid, hydrogen is evolved and a deep blue complex is formed. Mercuric chloride and chloroauric acid are both reduced indicating the powerful reducing properties of the compound. It is hoped that, in the future, these and other reactions will be studied and the products isolated and identified.