Reactions of labile Vitamin 81 metal com~lexes, thiaminium tetrachlo­romercurate (II) monohydrate, Hg(Th)C14.H20, thiaminium tetrachlorocadmate (II) monohydrate, Cd(Th)C14.H20 and thiaminium tetrachlorozincate(ll) mono­hydrate, Zn(Th)C14.H20 with hexammineruthenium(lll) chloride, Ru(NH3)6C13 in aqueous medium (1:1 molar ratio) yielded hexammineruthenium (III) pentachlo­romerucrate(II), Ru(NH3)6H9C1S' hexammineruthenium(lll) pentachlorocadmate (II),Ru(NH3)6CdC1S and hexammineruthenium(lll) pentachlorozincate(II),Ru(NH3)6ZnC15'respectively. These new compounds have been characterized by elemental analyses and irifrared spectra. The rationale for the particular geometry assumed by each of the HgC1S ,CdC1S and ZnC1S complex ions is discussed.