Enantiopure Amidinate Complexes of the Rare-Earth Elements

Abstract

The synthesis of the new chiral amidine (S,S)-N,N′-bis(1-phenylethyl)pivalamidine ((S)-HPETA) and its corresponding lithium salt (S)-LiPETA are reported, and their solid-state structures were investigated by single-crystal X-ray diffraction. Depending on the stoichiometric ratio and the ion radius of the rare-earth metal, the reaction of (S)-LiPETA with anhydrous lanthanide trihalides (Ln = Sc, Y, La, Nd, Sm, Lu) afforded mono-, bis-, and tris(amidinate) complexes. The mono(amidinate) compound [{(S)-PETA}LaI4Li2(thf)4], the bis(amidinate) complexes [({(S)-PETA}2Ln-μ-Cl)n] (Ln = Sc, Y, Nd, Sm, Lu), and the tris(amidinate) compound [{(S)-PETA}3Y] were isolated and structurally characterized by single-crystal X-ray diffraction. For the bis(amidinate) compounds, either monomeric or chloro-bridged dimeric structures were observed in the solid state. Furthermore, chiral bis(amidinate)-amido and -alkyl complexes [{(S)-PETA}2Ln{E(SiMe3)2}] (E = N, Ln = Y; E = CH, Ln = Sc, Y, Lu) were synthesized by salt metathesi...