Elusive Terminal Copper Arylnitrene Intermediates

摘要

We report herein three new modes of reactivity between arylazides N3Ar with a bulky copper(I) beta-diketiminate. Addition of N3ArX3 (Ar-X3 = 2,4,6-X3C6H2; X = Cl or Me) to [(Pr2NN)-Pr-i]Cu(NCMe) results in triazenido complexes from azide attack on the beta-diketiminato backbone. Reaction of [(Pr2NN)-Pr-i] Cu(NCMe) with bulkier azides N3Ar leads to terminal nitrenes [(Pr2NN)-Pr-i] 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-(Pr2C6H3)-Pr-i) 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 [(Pr2NN)-Pr-i]Cu=NAr that undergo nitrene group transfer to PMe3, (BuNC)-Bu-t, and even into a benzylic sp(3) C-H bond of ethylbenzene.