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(η^6-C_7H_8) (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(dπ)−N(pπ) interactions, resulting in two nearly degenerate singly occupied molecular orbitals (SOMOs) that are Ni−N π* 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═CH_2) (5) via an azanickelacyclobutane intermediate, (IPr*)Ni{N,C:κ^2-N(dmp)CH_2CH_2} (4)

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

This article discusses a two-coordinate nickel imido complex that effects C-H amination

Reductive coupling of carbon monoxide in carbonyl complexes with pendant Lewis acids or bases

An approach to conversion of light alkanes to value added mols. involves conversion via steam reforming to syngas, a mixt. of carbon monoxide and dihydrogen, with subsequent conversion to chems. and liq. fuels. Heterogeneous Fischer-Tropsch synthesis of hydrocarbons and oxygenates is well established, but selectvity is poor and subsequent upgrading to useful products is required. Recent progress has been made aimed at developing a homogeneous, more selective catalyst system for converting syngas to Cn>1 products by an approach involving two metals: one to coordinate carbon monoxide and to promote C-C bond formation, another to activate H2 and deliver it to CO and its partially reduced fragments. Recent progress toward using transition metal carbonyls with appended Lewis acid or bases will be discussed

Synthesis and Reactivity of Two-Coordinate Ni(I) Alkyl and Aryl Complexes

Reaction of [(IPr)­Ni­(μ-Cl)]₂ (<b>1-Cl</b>; IPr = 1,3-bis­(2,6-diisopropylphenyl)­imidazolin-2-ylidene) with ClMg­{CH­(SiMe₃)₂}·Et₂O affords (IPr)­Ni­{CH­(SiMe₃)₂} (<b>2</b>), a two-coordinate Ni­(I) alkyl complex. An analogous two-coordinate aryl derivative, (IPr)­Ni­(dmp) (dmp = 2,6-dimesitylphenyl), can be similarly prepared from Li­(dmp) and <b>1-Cl</b>. Reaction of <b>2</b> with alkyl bromides gives the three-coordinate Ni­(II) alkyl halide complex (IPr)­Ni­{CH­(SiMe₃)₂}­Br. Evidence for a radical mechanism is presented to explain the reaction of <b>2</b> with alkyl halides

Synthesis and Reactivity of Two-Coordinate Ni(I) Alkyl and Aryl Complexes

Reaction of [(IPr)­Ni­(μ-Cl)]₂ (<b>1-Cl</b>; IPr = 1,3-bis­(2,6-diisopropylphenyl)­imidazolin-2-ylidene) with ClMg­{CH­(SiMe₃)₂}·Et₂O affords (IPr)­Ni­{CH­(SiMe₃)₂} (<b>2</b>), a two-coordinate Ni­(I) alkyl complex. An analogous two-coordinate aryl derivative, (IPr)­Ni­(dmp) (dmp = 2,6-dimesitylphenyl), can be similarly prepared from Li­(dmp) and <b>1-Cl</b>. Reaction of <b>2</b> with alkyl bromides gives the three-coordinate Ni­(II) alkyl halide complex (IPr)­Ni­{CH­(SiMe₃)₂}­Br. Evidence for a radical mechanism is presented to explain the reaction of <b>2</b> with alkyl halides