Frustrated Lewis Pair‐Type Reactivity of Intermolecular Rare‐Earth Aryloxide and N‐Heterocyclic Carbene/Olefin Combinations

Abstract This work reports the cooperative reactivity of rare‐earth aryloxide complexes with N ‐heterocyclic carbene (NHC) or N ‐heterocyclic olefin (NHO), showcasing their synergistic effect on the activation of H 2 and diverse organic substrates. Reactions of RE(OAr) 3 (RE=La, Sm, and Y; Ar=2,6‐ t Bu 2 −C 6 H 3 ) with unsaturated NHC I t Bu (:C[N(R)CH] 2 , R= t Bu) isolated abnormally bound RE metal NHC complexes RE/ a NHC. In contrast, no metal‐NHO adducts were formed when RE(OAr) 3 were treated with NHO (R 2 C=C[N(R)C(R)] 2 , R=CH 3 ). Both RE/ a NHC and RE/NHO Lewis pairs enabled cooperative H 2 activation. Furthermore, RE(OAr) 3 were found to catalyze the hydrogenation of the exocyclic C=C double bond of NHO under mild conditions. Moreover, treatment of the La/ a NHC complex with benzaldehyde produced a La/C4 1,2‐addition product. The La/NHO Lewis pair could react with (trimethylsilyl)diazomethane and α , β ‐conjugated imine, affording an isocyanotrimethylsilyl lanthanum amide complex and a La/C 1,4‐addition product, respectively.