Catalytic C(sp²)–H Amination Reactions Using Dinickel Imides

Abstract

C−H amination reactions are valuable transformations for the construction of C−N bonds. Due to their relatively high bond dissociation energies, C(sp 2 )−H bonds are generally not susceptible toward direct nitrene insertion, necessitating alternative mechanisms for C−H activation. Here, we report that cationic dinuclear (NDI)Ni 2 (NDI = naphthyridine−diimine) complexes catalyze intramolecular nitrene insertions into aryl and vinyl C(sp 2 )− H bonds. Mechanistic studies suggest that a bridging imido ligand supported at a Ni 2 site induces C−H activation by a 1,2-addition pathway to generate an azametallacyclic intermediate. This organometallic mechanism contrasts with the electrocyclization/1,2-shift mechanism proposed for analogous transformations using Rh 2 catalysts. The implications of these mechanistic differences for the stereoselectivity and chemoselectivity of C−H amination are described.Article pubs.acs.org/Organometallics

Multiwavelets applied to metal–ligand interactions: Energies free from basis set errors

“…In order to illustrate how the BSSE and the counterpoise correction may affect the reaction energy of a specific reaction, consider reaction Ni- alkene-3 (Scheme 4), which has a medium-sized alkene as incoming ligand (alkenes are typical substrates in metal-catalyzed reactions 102 ) with a commonly used basis set, 6-311G(d,p). 31,33,34,104 The electronic association energy computed for this reaction is -14.0 kcal/mol with PBE/6-311G(d,p) (not including any other corrections). The computed BSSE at the same level is however 15.2 kcal/mol, resulting in an electronic association energy of +1.2 kcal/mol.…”

“…It is a relatively standard procedure in computational studies to perform single-point energy calculations with a larger basis set, using optimized geometries computed with a smaller basis set. In computational organometallic chemistry, such single-point corrections are often carried out with medium-sized TZ basis sets (such as 6-311G(d,p)), 31,33,34,35 however, the BSE in such basis sets may still be significant (vide infra). Although it is possible to use much larger basis sets (with smaller BSEs) for single point energies, this is rarely done and, as pointed out by Head-Gordon and coworkers, it is remarkably difficult to reach the basis set limit, requiring very large basis sets, such as the quintuple-zeta basis set pc-4.…”

“…It can be noted that the 6-311G(d,p) basis set is used in many contemporary studies for computing reaction energies of metal systems. 31,33,34,104,105,106 On basis of the shortcomings described here, it is strongly recommended to not use this basis set for computing energies.…”

“…26,27 Such basis sets may come in different sizes, with many contemporary studies reporting use of double-ζ (DZ) and medium-sized triple-ζ (TZ) basis sets for computing final energies. 28,29,30,31,32,33,34,35 All available basis sets are in practice finite basis sets, which invariably carry a certain Basis Set Error (BSE), defined as the difference in energy (E) between the complete basis set (CBS) result and the finite basis set (FBS) result.…”

A molecular substitutional disorder case study suitable for instruction: L 2CrII(THF)/L 2[(trimethylsilyl)methyl]CrIII (L is 2,5-bis{[(2,6-diisopropylphenyl)imino]methyl}pyrrol-1-ide)

“…In a structure displaying a Br À disordered with a m-terphenylimido ligand, there should be a space when Br À is present. No occupying moieties were modeled together with the Br À and it was unclear if the space is empty (Powers et al, 2020). Upon reflection, we recall a preliminary data set that was abandoned in favor of repeating the data collection on a chemically pure crystal obtained from an alternative synthetic route (Salisbury et al, 2007).…”