Pt-Sn and Ru Catalyst Precursors

The regioselective hydroformylation of functionalized and nonfunctionalized olefins can also be performed by platinum compounds [26] in chlorostannate ionic liquids as solvents for homogeneous catalysis (entries 20-22, Table 6.1). Dissolved in chlorostannate ionic liquids, the Pt catalyst shows enhanced stability and selectivity in the hydroformylation of methyl-3-pentenoate compared to the identical reaction in conventional organic solvents. The moderate Lewis acidity of these ionic liquids allows the activation of the Pt catalyst combined with tolerance of the functional groups in the substrate. In the case of 1-octene hydroformylation, a biphasic reaction system could be performed using the chlorostannate ionic liquid. 

The proposed active species ds-[Pt(PPh3)2Cl(SnCl3)] and c s-[Pt(PPh3)2(SnCl3)2] formed from the hydroformylation catalyst precursor cis-] Pt(PPh3)2Cl2] in the presence of SnCl2 have been identified [29]. 

More interestingly, Ru3(CO)i2 dissolved in 1,3-dialkylimidazolium-based ionic liquids, in particular those associated with chloride anion [49], effectively catalyzed the hydroformylation of various kinds of alkenes with carbon dioxide to give the corresponding alcohols (Table 6.2). Compared to the conventional reaction, this reaction proceeded in the biphasic system, where the chemoselectivity in the 

Entry Ionic liquid T(°C) Conversion (%) Heptanal yield (%) Hexane yield %) Reference 

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