Coordination Chemistry of Ester-Functionalized Cp Ligands. A Versatile Approach to the Chiral Hydroxyalkoxycarbonylcyclopentadienide [C₅H₄CO₂(CHMe)₂OH]^-. Synthesis, Structure, and Catalytic Activity of Rhodium(I) and Iron(II) Complexes

The ring-opening reaction of meso-4,5-dimethyl-1,3-dioxolan-2-one or (4S,5S)-dimethyl-1,3-dioxolan-2-one with NaCp yields the sodium hydroxyalkoxycarbonylcyclopentadienides Na[rac-C5H4CO2(CHMe)2OH] (1) and Na[(1S,2S)-C5H4CO2(CHMe)2OH] (2). Complexes of rhodium and iron have been prepared, and the X-ray molecular structures of [Rh{(1R,2S)-CpCO2(CHMe)2OH}(NBD)] (7) and [Rh{(1S,2S)-CpCO2(CHMe)2OH}(NBD)] (8) are reported. The rhodium complexes are catalytically active in the hydroformylation of hex-1-ene. Heptanal is the prevailing product with a regioselectivity up to 70%, while the residual olefin is mainly isomerized.