Boranes are widely used Lewis acids and N-heterocyclic carbenes (NHCs) are popular Lewis bases, so it is remarkable how little was known about their derived complexes until recently. NHC-boranes are typically readily accessible and many are so stable that they can be treated like organic compounds rather than complexes. They do not exhibit "borane chemistry", but instead are proving to have a rich chemistry of their own as reactants, as reagents, as initiators, and as catalysts. They have significant potential for use in organic synthesis and in polymer chemistry. They can be used to easily make unusual complexes with a broad spectrum of functional groups not usually seen in organoboron chemistry. Many of their reactions occur through new classes of reactive intermediates including borenium cations, boryl radicals, and even boryl anions. This Review provides comprehensive coverage of the synthesis, characterization, and reactions of NHC-boranes.

This works introduces hypervalent bis-catecholato silicon compounds as versatile sources of alkyl radicals upon visible-light photocatalysis. Using Ir[(dF(CF3)ppy)2(bpy)](PF6) (dF(CF3)ppy = 2-(2,4-difluorophenyl)-5-trifluoromethylpyridine, bpy = bipyridine) as catalytic photooxidant, a series of alkyl radicals, including highly reactive primary ones can be generated and engaged in various intermolecular homolytic reactions. Based on cyclic voltammetry, Stern-Volmer studies, and supported by calculations, a mechanism involving a single-electron transfer from the silicate to the photoactivated iridium complex has been proposed. This oxidative photocatalyzed process can be efficiently merged with nickel-catalyzed Csp2-Csp3 cross-coupling reactions.