Ruthenium aryloxide complex

Hartwig JF, Bergman RG, Andersen RA (1991) Insertion reactions of CO and CO2 with ruthenium benzyl, arylamido, and aryloxide complexes a comparison of the reactivity of ruthenium-carbon, ruthenium-nitrogen, and ruthenium-oxygen bonds. J Am Chem Soc 113 6499-6508... 

Figure 12.7 Ruthenium complexes with increased rigidity of the chelate ring (31, 32), and fluoro aryloxide anionic ligands (33-35).

As a result, the pyridine ligand is more labile in complex 16 and 17 than in 15 resulting in higher metathesis activity. It must be noted that the presence of the aryloxide ligands increased the affinity of these complexes for silica thus allowing an efficient removal of ruthenium contaminants by a single column chromatography purification. 

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