Half-sandwich chiral rare-earth metal complexes with linked tridentate amido-indenyl ligand: synthesis, characterization, and catalytic properties for intramolecular hydroamination

The enantioselective intramolecular hydroamination of alkenes with free amines has been a touchstone reaction in the development of many new chiral rare-earth (RE) metal complexes. In this article, we describe the synthesis and characterization of four novel rare-earth metal (Y, Sm, Lu, Sc) complexes, featuring a tridentate carbon-linked amido-indenyl ligand with a shortened linker between the indene ring and the chiral diamine moiety, as compared to our previously developed structurally similar silicon-linked ligand. Despite the generally lower enantioselectivities obtained in the current work, the structure–activity analyses of these complexes based on X-ray crystallographic data could be useful for further development of highly efficient chiral rare-earth metal complexes for asymmetric synthesis.