Zusammenfassung
The chiral-at-metal complexes (R-Fe,R-C )/(S-Fe,R-C )-[CpFe(Prophos)NCR]X (X = I, PF6 ; R = Et, Ph, p-substituted Ph) were prepared, and the diastereomers were separated by fractional crystallization. Eight diastereomerically pure complexes (S-Fe,R-C)-[CpFe(Prophos)NCR]X could be characterized by X-ray crystallography. The kinetics of epimerization with respect to the labile Fe-configuration in ...
Zusammenfassung
The chiral-at-metal complexes (R-Fe,R-C )/(S-Fe,R-C )-[CpFe(Prophos)NCR]X (X = I, PF6 ; R = Et, Ph, p-substituted Ph) were prepared, and the diastereomers were separated by fractional crystallization. Eight diastereomerically pure complexes (S-Fe,R-C)-[CpFe(Prophos)NCR]X could be characterized by X-ray crystallography. The kinetics of epimerization with respect to the labile Fe-configuration in CDCl3 at ambient temperatures was measured for the EtCN, PhCN, and (p-C6H4NMe2 ) complexes. The half-lives of 162 and 760 min of the 40 first-order reactions of (S-Fe,R-C)-[CpFe(Prophos)NCPh]PF6 and (S-Fe,R-C)-[CpFe(Prophos)NC(p-C6H4NMe2)]PF6 at 293 K demonstrate the importance of the inductive effect in the rate-determining cleavage of the Fe-NCR bond. The diastereomer ratios of 5:95 to 10:90 at equilibrium under thermodynamic control were strongly in favor of the (S-Fe,R-C )-[CpFe(Prophos)NCR]X diastereomers. In ligand exchange reaction reactions, (R-Fe,R-C)/(S-Fe,R-C ) diastereomer ratios of up to 35:65 were observed under kinetic control.
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