Hexaammine complexes reduction

The preparation of the hexaammine complexes of ruthenium(II) and ruthenium (III) salts are sketchily described in the literature. The preparation of hexaammineruthenium(II) by the reduction of ruthenium trichloride with zinc in ammonia is described briefly by Lever and Powell.1 Allen and Senoff2 carry out the reduction using hydrazine hydrate. The hexaammineruthe-nium(III) cation is obtained by oxidation of the ruthenium(II) complex,1 and pentaamminechlororuthenium(III) dichloride is obtained by treating the former compound with hydrochloric acid.1,3 This compound may also be obtained by treating the pentaammine molecular nitrogen complex of ruthenium(II) with hydrochloric acid.2,4... 

Analogous principles apply when metal ions in different oxidation states form complexes with the same ligand usually, the metal ion in the higher oxidation state is stabilized to a greater extent than that in the lower oxidation state. Equations 7.36 and 7.37 show the reduction of hexaaqua and hexaammine complexes of Co(III) remember thatM (aq) represents [M(H20) ] +(aq) (see Section 6.12). 

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