Reactions of a Bis(vinyltrimethylsilane)nickel(0) N-Heterocyclic carbene complex with organic azides

Abstract

The reactions of three-coordinate iron(0) and cobalt(0) alkene complexes (NHC)M(η2-CH2CHSiMe3)2 (NHC = N-heterocyclic carbene, M = Fe, Co) with organic azides proved an effective way for the preparation of iron and cobalt terminal imido complexes. The relevant reactions of nickel(0) alkene complex (NHC)Ni(η2-CH2CHSiMe3)2 with organic azides, however, have remained unexplored. Herein, we report the study on the reactions of [(IPr)Ni(η2-CH2CHSiMe3)2] (IPr = 1,3-bis(2′,6′-diisopropylphenyl)imidazole-2-ylidene) with organic azides. The interaction of [(IPr)Ni(η2-CH2CHSiMe3)2] with 2,6-dimesitylphenyl azide (DmpN3) produced the two-coordinate imido complex [(IPr)Ni(NDmp)] (1) in a trace amount with the starting materials being largely remained. The reaction of [(IPr)Ni(η2-CH2CHSiMe3)2] with 2,6-diisopropylphenyl azide (DippN3) gave IPrNNNDipp (2) as the only isolable product. The interaction of [(IPr)Ni(η2-CH2CHSiMe3)2] with PhC(CF3)2N3 produced an azanickelacyclobutane compound [(IPr)Ni(κ-C,N–N(C(CF3)2Ph)CH(SiMe3)CH2)] (3) in high yield. The different products formed in these reactions reflect the influence of the steric and electronic nature of organic azides on reaction outcomes. Further study on the azanickelacyclobutane complex 3 indicated that it can convert into a new azanickelacyclobutane [(IPr)Ni(κ-C,N–N(C(CF3)2Ph)CH2CHSiMe3)] (4). A nickel(II) amido alkyl complex [(IPr)Ni(NHC(CF3)2Ph)(CH2CHNC(CF3)2Ph)] (5) was also isolated from the decomposition reaction of 3.