Chiral bridged aminotroponiminate complexes of the lanthanides

Abstract

The enantiomerically pure bridged aminotroponimines, S,S- and R,R-H₂{(iPrATI)₂diph}, in which two amino-isopropyl-troponimine moieties are linked by 1,2-diamino-1,2-diphenylethane, were deprotonated with nBuLi to give the corresponding dilithium salts [{Li(THF)}₂{(S,S)-(iPrATI)₂diph)}] (1a) and [{Li(THF)}₂{(R,R)-(iPrATI)₂diph)}] (1b). The potassium salts [{K(THF)₂}₂{(S,S)-(iPrATI)₂diph}] (2a) and [{K(THF)₂}₂{(R,R)-(iPrATI)₂diph}] (2b) were obtained by a deprotonation reaction with KH. Transmetallation of 2a and 2b with anhydrous lanthanide trichlorides led to [(S,S)-{(iPrATI)₂diph}LnCl(THF)] (Ln = Ho (3a), Er (4a)) and [(R,R)-{(iPrATI)₂diph}LnCl(THF)] (Ln = Ho (3b), Er (4b), Yb (5b)), respectively. The corresponding Yb complex [(S,S)-{(iPrATI)₂diph}YbCl(THF)] (5a) was obtained by treatment of 1a with YbCl₃ at elevated temperature. Performing the same reaction at room temperature results in the metallate complex [(S,S)-{(iPrATI)₂diph}YbCl₂][Li(THF)₄] (6). Reaction of NaC₅H₅ with 5a afforded [(S,S)-{(iPrATI)₂diph}Yb(η⁵-C₅H₅)(THF)] (7). The structures of 1a, 3a, 4a, 5a, 5b, 6, and 7 were confirmed by single crystal X-ray diffraction in the solid-state.