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

Abstract

The pharmacologically active [Ru(CO)₃Cl(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)₃Cl(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)₃Cl(glycinate)] with HCl gives [Ru(CO)₃Cl₂(NH₂CH₂CO₂H)]. The crystal structures of [Ru(CO)₃Cl(glycinate)] and [Ru(CO)₃Cl₂(NH₂CH₂CO₂Me)] are reported.