Elusive Terminal Copper Arylnitrene Intermediates

We report herein three new modes of reactivity between arylazides N 3 Ar with a bulky copper(I) β‐diketiminate. Addition of N 3 Ar X3 (Ar X3 =2,4,6‐X 3 C 6 H 2 ; X=Cl or Me) to [ i Pr 2 NN]Cu(NCMe) results in triazenido complexes from azide attack on the β‐diketiminato backbone. Reaction of [ i Pr 2 NN]Cu(NCMe) with bulkier azides N 3 Ar leads to terminal nitrenes [ i Pr 2 NN]Cu]=NAr that dimerize via formation of a C−C bond at the arylnitrene p ‐position to give the dicopper(II) diketimide 4 (Ar=2,6‐ i Pr 2 C 6 H 3 ) or undergo nitrile insertion to give diazametallocyclobutene 8 (Ar=4‐Ph‐2,6‐iPr 2 C 6 H 2 ). Importantly, reactivity studies reveal both 4 and 8 to be “masked” forms of the terminal nitrenes [ i Pr 2 NN]Cu=NAr that undergo nitrene group transfer to PMe 3 , t BuNC, and even into a benzylic sp 3 C−H bond of ethylbenzene.