Metal carbonyls as pharmaceuticals? [Ru(CO)(3)Cl(glycinate)], a CO-releasing molecule with an extensive aqueous solution chemistry

The pharmacologically active [Ru(CO)(3)Cl(glycinate)] is shown to be in equilibrium with [Ru(CO)(2)(CO2H) Cl(glycinate)](-) (isomers) at around pH 3.1 which then at physiological pH reacts with more base to give [Ru(CO)(2)(CO2) Cl(glycinate)](2-) (isomers) or [Ru(CO)(2)(CO2H)(OH)(glycinate)](-)( isomers). The ease with which [Ru(CO)(3)Cl( glycinate)] reacts with hydroxide results in it producing a solution in water with a pH of around 2 to 2.5 depending on concentration and making its solutions more acidic than those of acetic acid at comparable concentrations. Acidification of [Ru(CO)(3)Cl(glycinate)] with HCl gives [Ru(CO)(3)Cl-2(NH2CH2CO2H)]. The crystal structures of [Ru(CO)(3)Cl(glycinate)] and [Ru(CO)(3)Cl-2(NH2CH2CO2Me)] are reported.