Reversible modulation of the local environment around metal centers bearing multifunctional carbenes

Abstract

Abstract This Highlight Review provides examples of external-stimuli-driven reversible modulations of the spatial, electronic, and magnetic environment around metal centers that bear multifunctional N-heterocyclic carbenes (NHCs). In particular, recent reports on Lewis-base- or Lewis-acid-mediated reversible molecular transformations of Ni(0) complexes that bear N-phosphine-oxide-substituted imidazolylidenes (PoxIms) and the corresponding imidazolinylidenes (SPoxIms) are spotlighted. We also discuss the utility of using X-ray absorption spectroscopy to examine the synthesized (S)PoxIm–Ni complexes to gain spectroscopic insight into the changes in the local environment and electronic state of the metal centers induced by these reversible transformations. Overall, this review highlights the multipurpose utility of multifunctional NHCs as a key to designing and reversibly modulating the local environment of metal centers, which paves the way for accomplishing hitherto challenging molecular transformations and developing unprecedented reactivity of multimetallic compounds.