Frustrated Lewis Pair‐Like Reactivity of Rare‐Earth Metal Complexes: 1,4‐Addition Reactions and Polymerizations of Conjugated Polar Alkenes

Three rare‐earth aryloxide ion pairs {[L1REOAr]+/[B(C6F5)4]−; L1=CH3C(2,6‐iPr2C6H3N)CHC(CH3)(NCH2CH2PPh2); RE=Sc, Y, Lu; Ar=2,6‐tBu2C6H3} were reported that feature rare‐earth/phosphorus (RE/P) combinations exhibiting frustrated Lewis pair (FLP)‐like 1,4‐addition reactions towards conjugated carbonyl substrates (e.g., enone, ynone, and acrylic substrates). Furthermore, these RE/P complexes were found to be effective catalysts for the polymerization of conjugated polar alkene monomers. Mechanistic studies revealed that the rare‐earth metal‐catalyzed polymerizations were initiated by new FLP‐type 1,4‐additions rather than traditional and ubiquitous covalent RE−E (E=H, C, N, etc.) bond insertion or single‐electron transfer.