title: The curious case of mesityl azide and its reactivity with bpyNiEt2.
abstract: A DFT analysis of the reaction of bpyNiEt2 with ArN3 was performed for para-tolyl-azide (Ar = pTol), 3,5-dimethyl-phenyl-azide (Ar = mXy) and ortho-tolyl-azide (Ar = oTol), and mesityl-azide (MesN3). Of particular interest were the different products obtained for the latter (ethylene, butane, azomesitylene, mesityl-ethylamine, etc.) versus the other reagents, i.e., (bpyNi(N(Ar)Et)(Et)). Calculated thermodynamics and kinetics for metal-free reactions did not differentiate MesN3 from the other aryl azides. Once (2)bpyNiEt(•) was generated via bond homolysis, formation of ethylene by β-H elimination was facile, as was formation of nickel-imidyl (NR(-•)) intermediates by reaction of ArN3 with bpyNiEtx (x = 0-2). On the basis of computed energetics, three reactions of bpyNiEt2 were proposed to compete: Ni-C bond homolysis, reductive elimination of butane, and nucleophilic attack (NA) by ArN3. Inspection of their temperature dependence suggested that NA and Ni-Et bond homolysis dominated at lower and higher temperatures, respectively. Calculated Ni-N and Ni-C bond dissociation free energies (BDFEs) suggested the role of radical pathways in discriminating bpyNiEt2/ArN3 reactions, and implied that the concentration of radicals such as aminyl (ArN(•)(Et)), (2)bpyNiEt(•), and Et(•) will be greatest for MesN3.
authors.affiliation: Department of Chemistry, Center for Advanced Scientific Computing and Modeling, University of North Texas , 1508 Mulberry, Denton, Texas 76203, United States.
authors.forename: Brooke M
authors.initials: BM
authors.lastname: Otten
authors.forename: Travis M
authors.initials: TM
authors.lastname: Figg
authors.forename: Thomas R
authors.initials: TR
authors.lastname: Cundari