Reaction of [(IPr)Ni(μ-Cl)]2 (1-Cl; IPr = 1,3-bis(2,6-diisopropylphenyl)imidazolin-2-ylidene) with ClMg{CH(SiMe3)2}·Et2O affords (IPr)Ni{CH(SiMe3)2} (2), 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 1-Cl. Reaction of 2 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 2 with alkyl halides.
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http://dx.doi.org/10.1021/ja4095236 | DOI Listing |
Inorg Chem
January 2022
Department of Chemistry, University of Bath, Claverton Down, Bath BA2 7AY, U.K.
We report a new series of homoleptic Ni(I) bis-N-heterocyclic carbene complexes with a range of torsion angles between the two ligands from 68° to 90°. Electron paramagnetic resonance measurements revealed a strongly anisotropic -tensor in all complexes with a small variation in ∼ 5.7-5.
View Article and Find Full Text PDFChem Commun (Camb)
June 2019
Department of Chemistry, University of California, Berkeley, California, USA.
The synthesis and reactivity of the first open-shell two-coordinate silyl complex, (IPr)Ni-Si(SiMe), (IPr = 1,3-di(2,6-di-iso-propylphenyl)imidazolin-2-ylidene) is reported. Reaction with CO results in a novel insertion product that possesses a distorted geometry. Oxidations of the Ni center, with [CpFe][B(CF)] and PhCCl, result in migratory rearrangements of the silyl ligand, apparently via related silylene intermediates.
View Article and Find Full Text PDFChemistry
January 2018
Institut für Anorganische und Analytische Chemie, Freiburger Materialforschungszentrum (FMF), Universität Freiburg, Stefan-Meier-Straße 21, 79104, Freiburg, Germany.
The recently published purely metallo-organic Ni salt [Ni(cod) ][Al(OR ) ] (1, cod=1,5-cyclooctadiene, R =C(CF ) ) provides a starting point for a new synthesis strategy leading to Ni phosphine complexes, replacing cod ligands by phosphines. Clearly visible colour changes indicate reactions within minutes, while quantum chemical calculations (PBE0-D3(BJ)/def2-TZVPP) approve exergonic reaction enthalpies in all performed ligand exchange reactions. Hence, [Ni(dppp) ][Al(OR ) ] (2, dppp=1,3-bis(diphenylphosphino)propane), [Ni(dppe) ][Al(OR ) ] (3, dppe=1,3-bis(diphenyl-phosphino)ethane), three-coordinate [Ni(PPh ) ][Al(OR ) ] (4) and a remarkable two-coordinate Ni phosphine complex [Ni(PtBu ) ][Al(OR ) ] (5) were characterised by single crystal X-ray structure analysis.
View Article and Find Full Text PDFChemistry
November 2017
Institute of Chemical Research of Catalonia, The Barcelona Institute of Science and Technology, Avgda. Països Catalans 16, 43007, Tarragona, Spain.
Density functional theory (DFT) calculations have been used to study the oxidative addition of aryl halides to complexes of the type [Ni(PMe Ph ) ], revealing the crucial role of an open-shell singlet transition state for halide abstraction. The formation of Ni versus Ni has been rationalised through the study of three different pathways: (i) halide abstraction by [Ni(PMe Ph ) ], via an open-shell singlet transition state; (ii) S 2-type oxidative addition to [Ni(PMe Ph ) ], followed by phosphine dissociation; and (iii) oxidative addition to [Ni(PMe Ph ) ]. For the overall reaction between [Ni(PMe ) ], PhCl, and PhI, a microkinetic model was used to show that our results are consistent with the experimentally observed ratios of Ni and Ni when the PEt complex is used.
View Article and Find Full Text PDFAngew Chem Int Ed Engl
October 2016
Department of Chemistry, The University of British Columbia, Vancouver, BC, V6T 1Z1, Canada.
Amidate-supported two- and three-coordinate Ni complexes were synthesized by reduction of the corresponding Ni precursors. A dramatic change in binding mode is observed upon reduction from Ni to Ni . The Ni derivatives include an unprecedented Ni bis(C-H) agostic complex and a two-coordinate Ni complex.
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