Heterobimetallic Rare Earth–Lithium Complexes with Fewer Than Three Binaphtholates

Heterobimetallic rare earth–alkali metal binaphtholates (REMBs) are exquisite catalysts for asymmetric synthesis (Shibasaki catalysts). All solid‐state structures reported so far correspond to the general formula M 3 RE[( S )‐binolate] 3 (RE/M/B = 1:3:3 stoichiometry). We have synthesized and characterized crystallographically new complexes of this category, namely Li 3 RE[( S )‐binolate] 3 · x THF [RE = Sc ( 2 ), Sm ( 3 )] and Li 3 Nd[( S )‐binolate] 3 · 6THF · LiCl ( 4 ). The latter is the first reported adduct between a REMB and LiCl. We have also crystallized a rare type of REMB of 1:2:2.5 stoichiometry: Li 4 Sm 2 [( S )‐binolate] 5 · 6THF · 2H 2 O ( 5 ). Such a complex has only one precedent in the literature. The use of ( S )‐3,3′‐dimesityl‐1,1′‐binaphthyl‐2,2′‐diol ( 6 ) as ligand precursor allowed us to obtain the first X‐ray structures of unprecedented REMBs of 1:1:1 and 1:1:2 stoichiometries: {[( S )‐ 6 ]RECl 2 (THF) 2 }[Li(THF) 2 ] [RE = Y ( 7 ), Sm ( 8 )] and LiY[( S )‐ 6 ] 2 · 2THF ( 9 ).