A Two-Coordinate Nickel Imido Complex That Effects C-H Amination

An exceptionally low coordinate nickel imido complex, (IPr*)Ni=N(dmp) (2) (dmp = 2,6-dimesitylphenyl), has been prepared by the elimination of N-2 from a bulky aryl azide in its reaction with (IPr*)Ni(eta(6)-C7H8) (1). The solid-state structure of 2 features two-coordinate nickel with a linear C-Ni-N core and a short Ni-N distance, both indicative of multiple-bond character. Computational studies using density functional theory showed a Ni=N bond dominated by Ni(d pi)-N(p pi) interactions, resulting in two nearly degenerate singly occupied molecular orbitals (SOMOs) that are Ni-N pi* in character. Reaction of 2 with CO resulted in nitrene-group transfer to form (dmp)NCO and (IPr*)Ni(CO)(3) (3). Net C-H insertion was observed in the reaction of 2 with ethene, forming the vinylamine (dmp)NH(CH=CH2) (5) via an azanickelacyclobutane intermediate, (IPr*)Ni{N,C:kappa(2)-N(dmp)CH2CH2} (4).