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

Abstract

Three rare-earth aryloxide ion pairs {[L1REOAr]+ /[B(C6 F5 )4 ]- ; L1=CH3 C(2,6-iPr2 C6 H3 N)CHC(CH3 )(NCH2 CH2 PPh2 ); RE=Sc, Y, Lu; Ar=2,6-tBu2 C6 H3 } 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.