Chelating phosphorus ligands

ARCO An intermediate for 1,4-butanediol Rhodium catalyst with chelating phosphorus ligand hydroformylation of allyl alcohol followed by hydrogenation of the resultant aldehyde Reaction 5.9... 

Phosphorus ligands are crucial for the stabilization of the systems and the complex cis-[PtCl2(PPh3)2] (16) is most often employed, but complexes with chelating diphosphines also have been studied extensively. The stability of the related alkyl- and acylplatinum(II) complexes has favored extensive mechanistic investigations based on studies of the reactivity of model complexes. 

Since our first model system is achiral, we did not need to consider different diastereomeric manifolds. However, we did need to follow four different reaction pathways corresponding to the four possible cis -dihydride isomers (Figure 5). Intermediates with traits phosphorus orientations were not considered because the catalysts of interest have chelating diphosphine ligands. 

Assemblies based on 8 and pyridine phosphorus ligands 5-7 were used as supramolecular ligands in the rhodium-catalyzed hydroformylation and showed typical bidentate behavior. The chelating bidentate assembly exhibited lower activities (a factor of three) than the monodentate analogue. Only a slightly higher selectivity for the linear aldehyde was observed. The chiral ligand assemblies based... 

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