Development of metal complexes equipped with structurally flexible carbenes

Abstract

We herein summarize our recent results on the design and application of metal complexes that bear N-phosphine-oxidesubstituted imidazolylidenes (PoxIms), in which the volume and shape of the reaction space around the carbene atoms can be drastically changed via the rotation of the N-phosphinoyl groups; this phenomenon is discussed in detail based on experimental and theoretical results. We also discuss the application of PoxIms to implement the frustration revival strategy via the synthesis of external stimuli-responsive Lewis acidbase adducts that are comprised of PoxIms and B(C6F5)3, as well as to the phosphinoylation of CO2 and carbonyl compounds. The results presented in this Account have expanded the frontiers of multifunctional N-heterocyclic carbenes, which had previously been employed mainly as multidentate ligands for metal complexes.