Rubidium Nitrosochlor-ruthenate, Rb₂RuCl₅.NO

Rubidium Nitrosochlor-ruthenate, Rb₂RuCl₅.NO, is precipitated as a rather pale purple anhydrous salt on mixing concentrated solutions of rubidium chloride and ruthenium nitrosochloride. On recrystallisation from hot water very dark crystals are obtained.

If, however, dilute solutions of the above two compounds are mixed and evaporated over sulphuric acid the dihydrated salt, Rb₂RuCl₅.NO.2H₂O, separates out as large, dark purple crystals. These lose their water of crystallisation after further standing over concentrated sulphuric acid. The hydrated crystals are monoclinic and isomorphous with the corresponding caesium salt.