382. Ruthenium red

Abstract

Experiments have shown * that the ruthenium red cation is [Ru,O,(NH,), J6+ in which there are two oxo-bridges and the average oxidation number of ruthenium is + 10/3. The cation is oxidised reversibly by a one-electron change to the more paramagnetic brown cation [Ru,O,(NH,), J7+. The relation to other polynuclear complexes is discussed. JOLY formulated ruthenium red as Ru,Cl4(OH),,7NH3,3H,O, and Morgan and Burstall,2 who prepared from it supposed mononuclear complexes of ruthenium, as [Ru11x(OH)Cl(NH,),]C1,H20. The latter structure was rejected by Gleu and Breuel3 because [RuIrl(OH)C1(NH,),] + is paramagnetic whereas ruthenium red is diamagnetic.It has been suggested that the highly coloured cation is polynuclear, but further evidence on its structure has not been advanced.Our interest in ruthenium red arose from a view that the diamagnetism and intense colour of many complexes of ruthenium are due to their being polynuclear. In particular, the occurrence in solution of an aquochloro-* and an aquonitrato-complex 5 3 6 as transient violet species with unusually high molar extinction coefficients (cRU -20,000 at A , , -550 mp) suggested a chromatic group similar to that in ruthenium red for which we find that cRu is 21,000 at A, , , 532 mv. It has now been shown that this cation, here called ruthenium red, has no complexed halogen groups, and behaves as a trinuclear complex in which, associated with three ruthenium atoms, there are 14 nitrogen atoms which can be liberated as ammonia. This suggests that the red cation has two oxo-bridges, as in (I), to satisfy hexa-co-ordination of the ruthenium atoms. This cation is oxidised, reversibly, [(NH3),R~-O-R~(NH,)4-O-Ru(NH3)5]6+ [( N H 3)5 Ru-O-Ru (N H3I4-O-Ru (N HJJ ' + (I) Red (11) Brown in acid solution to a brown cation (11). in the respective cations are 10/3 and 1113. red cation points to a linear configuration of the Ru-O-Ru-O-Ru group.

Role of Ca2+ in regulating the level of mitochondrial pyrophosphate

“…Ruthenium red was recrystallized from the commercial preparation [25]. The pyrophosphate : fructosed-phosphate 1-phosphotransferase used for PPi assays was a gift of Dr W.E.…”

Structure of Ni(II) and Ru(III) Ammine Complexes Grafted onto Mesoporous Silicate Sieve

“…30,31 This mixed-valence oxo-bridged ruthenium trimer can be identified by a strong absorption at 532 nm (ε max = 21000, in water). 30 As can be seen in …”

A low molecular weight ruthenium complex inhibitory to mitochondrial Ca2+ transport

“…Six distinct peaks are apparent, three in the visible region and three in the ultraviolet. The peak at 536 nm and the shoulder at 477 nm are due to Ruthenium Red and Ruthenium Brown respectively [3] ; the peak at 355 nm is partially attributable to these complexes [3,6] but is due also to an additional component since its height is not related to the height of the visible peaks for Ruthenium Red and Brown. The radioactivity due to lo3 Ru, and hence the proportion of total ruthenium, is greatest in fractions seven and eight (fig.…”

“…Two g of RuC13, 3H2 0 and 34 &i ' O3 Ru were used as the starting materials in the synthetic procedure described by Fletcher et al [6]. The supernatants from successive Ruthenium Red crystallizations were combined, and this solution was used as the source of material in subsequent analyses.…”

“…However, such preparations generally contain less than 20% of the pure compound [3]. Recent studies in this laboratory [4, 51, which concentrated on the mechanism of inhibition of the Ca*+ carrier by pure Ruthenium Red ([(NH& Ru-0-Ru(NH&,-0-Ru (NH&] 6+Cl& 4H2 0; [6] ), suggested that a colourless contaminant of the crude preparations has inhibitory properties similar to those of Ruthenium Red itself.…”