ECE-Type Pincer Complexes of Nickel

Zargarian, Davit; Castonguay, Annie; Spasyuk, Denis

doi:10.1007/978-3-642-31081-2_5

Cited by 56 publications

(43 citation statements)

References 98 publications

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“…The trans angles in 4a and the P1−Ni−P2 angle in 3a are not affected much (174−176°); the latter is much larger than the corresponding angle in POCOP complexes. 20 On the other hand, the C−Ni−Br angle of 165°i n 3a is much smaller than the ideal value expected for a trans angle, presumably due to steric repulsions between Br and the noncyclometalated phosphinite.…”

Section: ■ Results and Discussionmentioning

confidence: 97%

Ortho Derivatization of Phenols through C–H Nickelation: Synthesis, Characterization, and Reactivities of Ortho-Nickelated Phosphinite Complexes

2014

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Reported here are the synthesis and characterization of ortho-nickelated complexes derived from phosphinite ligands and investigated as model compounds in the development of C−H functionalization strategies for arenol substrates. Reaction of i-Pr 2 POPh with 0.6 equiv of [(i-PrCN)NiBr 2 ] n and 0.8 equiv of NEt 3 in toluene (100°C, 36 h) gave the yellow, monomeric cyclometalated complex trans-{κ 2 P,C-C 6 H 4 OP(iPr) 2 }Ni(i-Pr 2 POPh)Br (3a) in 93% yield. The closely related yellow-orange dimeric species [{κ 2 P,C-C 6 H 4 OP(i-Pr) 2 }Ni(μ-Br)] 2 (4a) was obtained in 70% yield when i-Pr 2 POPh was treated with 2 equiv each of the Ni precursor and NEt 3 . These complexes have been characterized fully and shown to interconvert in the presence of excess ligand (4a → 3a) or excess Ni precursor (3a → 4a). Treatment of 3a or 4a with benzyl bromide at 90°C over extended periods led to benzylation of the Ni−aryl moiety in these complexes. Examination of the cyclometalation pathway for i-Pr 2 POPh has shown that the first species formed from its ambient-temperature reaction with [(iPrCN)NiBr 2 ] n is trans-(i-Pr 2 POPh) 2 NiBr 2 (2a). NMR studies showed that 2a undergoes a rapid ligand exchange at room temperature, which can be slowed down at −68°C; this fluxional process shifts in the presence of NEt 3 , implying the partial formation of an amine adduct. Heating toluene mixtures of 2a and NEt 3 at 90°C for 38 h led to the formation of 3a via C−H nickelation. That phosphinite dissociation from 2a precedes the C−H nickelation step is implied by the observation that the formation of 3a is hindered in the presence of excess i-Pr 2 POPh. The impact of phenol ring substituents on the C−H nickelation rate was probed by preparing substituted derivatives of 2a, trans-(4-R-C 6 H 4 OP(i-Pr 2 )} 2 NiBr 2 (R = OMe (2b), Me (2c), COOMe (2d)), and measuring their relative rates of C−H nickelation. These studies showed that the formation of cyclonickelated products is favored in the order COOMe < Me < OMe, which is consistent with an electrophilic nickelation mechanism. Studying the C−H nickelation of 3-F-C 6 H 4 OP(i-Pr 2 ) allowed us to establish that metalation is favored at the para position with respect to F (85:15).

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Section: ■ Results and Discussionmentioning

confidence: 97%

Ortho Derivatization of Phenols through C–H Nickelation: Synthesis, Characterization, and Reactivities of Ortho-Nickelated Phosphinite Complexes

2014

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“…Although there have been some excellent recent reviews dealing with pincer complexes of nickel in a general manner [24][25][26], the increasing interest and research development on POCOP-Ni compounds and the study of their chemistry and catalytic applications have accelerated in the last lustrum, which is due to an improved comprehension of these systems and the discovery of novel applications. These developments have, in a way, served as inspiration for the study of similar systems based on other metals such as iron and cobalt.…”

Section: Introductionmentioning

confidence: 99%

Recent Advances on the Chemistry of POCOP–Nickel Pincer Compounds

Asay

Morales‐Morales

2015

The Privileged Pincer-Metal Platform: Coordination Chemistry &Amp; Applications

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“…7 The increasing popularity of POCOP complexes in comparison to their PCP counterparts (Chart 1) is partly due to the significant stability of POCOPbased systems toward aerobic and thermal decomposition, as well as the greater ease and simplicity of their preparation relative to PCP-type ligands. 8 A typical synthesis of resorcinol-based POCOP-type complexes of Ni or Pd begins with the preparation of the ligand R′-POC(H)OP R by the reaction of resorcinol or its substituted derivatives with chlorophosphines. The resulting ligand is then reacted with a suitable metal precursor MX n to generate the desired complexes (R′-POCOP R )MX n−1 (Scheme 1).…”

Section: Introductionmentioning

confidence: 99%

Direct, one-pot synthesis of POCOP-type pincer complexes from metallic nickel

2013

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A one-pot procedure has been developed for the direct and atom-economical preparation of the pincertype complexes 3, 2 ). This convenient synthetic protocol involves heating a 1 : 2 : 1-2 mixture of resorcinol (or its substituted derivatives), R 2 PCl, and nickel powder in toluene (at 100 °C) or acetonitrile (at 75 °C) for 18 h. The target nickel compounds can be obtained from this procedure in up to 93% yield.Using metallic palladium in this protocol instead of nickel gives the corresponding palladium complexes in low yields only (ca. 10%). Chart 1Scheme 1 † Electronic supplementary information (ESI) available: Tables of crystal dataand collection/refinement parameters. Complete details of the X-ray analyses. CCDC 928921 (2), 928922 (3) and 928920 (4). For ESI and crystallographic data in CIF or other electronic format see

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ECE-Type Pincer Complexes of Nickel

Cited by 56 publications

References 98 publications

Ortho Derivatization of Phenols through C–H Nickelation: Synthesis, Characterization, and Reactivities of Ortho-Nickelated Phosphinite Complexes

Ortho Derivatization of Phenols through C–H Nickelation: Synthesis, Characterization, and Reactivities of Ortho-Nickelated Phosphinite Complexes

Recent Advances on the Chemistry of POCOP–Nickel Pincer Compounds

Direct, one-pot synthesis of POCOP-type pincer complexes from metallic nickel

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