Single-electron oxidation of N-heterocyclic carbene-supported nickel amides yielding benzylic C–H activation†
Abstract
The dimeric Ni(I)–Ni(I) N-heterocyclic carbene complex {(IPr)Ni(μ-Cl)}2 (3; IPr = 1,3-(2,6-iPr2C6H3)2imidazolin-2-ylidene)) reacts with the lithium terphenylamides LiNHdmp and LiNHdippp (dmp = 2,6-di(mesityl)phenyl; dippp = 2,6-bis(2,6-di-iso-propylphenyl)phenyl) to give the monomeric Ni(I) amides (IPr)Ni(NHdmp) (4) and (IPr)Ni(NHdippp) (5), respectively. These nickel amides are 1-electron paramagnets, and crystallographic characterization indicates both are stabilized by Ni–C(ipso) interactions with a flanking aryl group of the terphenyl fragment. This results in significant deviation from the linear CNHC–Ni–N geometry typical for a two-coordinate transition-metal complex (112.17(9)° in 4, 116.41(9)° in 5). One-electron