1,1′-Ferrocene dicarboxylic acid pyridin-4-yl ester: A new bidentate ligand in arene ruthenium chemistry

1,1′-Ferrocene dicarboxylic acid pyridin-4-yl ester (1) is prepared from 1,1′-ferrocene dicarbonyl chloride and 4-hydroxypyridine. This new bidentate ferrocenoyl ligand reacts with the monocationic complex [(η6-p-cymene)2Ru2(μ-OH)3]+ to give the dicationic complex [(η6-p-cymene)2Ru2(μ-OH)2(1,1′- (NC5H4–OOC)2–Fc)]2+ (2) (Fc: C5H4–Fe–C5H4), isolated as a tetrafluoroborate salt. The single-crystal X-ray structure analysis of [2][BF4]2 reveals the ferrocenoyl pyridine ligand 1 to act as μ2-η2 chelating ligand in the dinuclear complex, having replaced a μ2-η1-hydroxo ligand.