Recent Advances on the Chemistry of POCOP–Nickel Pincer Compounds

Asay, Matthew; Morales‐Morales, David

doi:10.1007/3418_2015_135

Cited by 45 publications

(6 citation statements)

References 97 publications

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“…Apart from the straight forward synthesis, these two types of pincer ligands are also characterized by their delicate balance of the ligand electronics as well as the steric demands around the donor centers. Transition metal complexes supported by these two types of pincer ligands are especially important in organometallic chemistry and catalysis . The only difference of these two types of ligands is the linker (O vs NH) that connects the benzene ring and the phosphorus arms.…”

Section: Introductionsupporting

confidence: 52%

A Structure Comparison of Ni(II) Complexes Supported by PNCNP and POCOP Pincer Ligands

et al. 2020

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In order to compare the structure and property of the same metal center supported by different types of pincer ligands, a series of Ni(II) pincer complexes, [2,6‐(iPr2PNH)2C6H3]NiX (X=SH, 1 a; SPh, 1 b; SBn, 1 c; BH4, 1 d), were synthesized based on m‐(iPr2PNH)2C6H4 (PNCNP) and fully characterized by multinuclear NMR, FTIR, X‐ray crystallography and elemental analysis. The structures of complexes 1 a–d were compared with those of the corresponding Ni(II) complexes supported by a bis(phosphinite) (POCOP) pincer ligand, [2,6‐(iPr2PO)2C6H3]NiX (X=SH, 2 a; SPh, 2 b; SBn, 2 c; BH4, 2 d). It was found that the Ni‐Cipso and Ni−S bond lengths and the Ni⋅⋅⋅B distance in complexes 1 a–d are comparable to those in complexes 2 a–d; however, the Ni−P bond lengths in complexes 1 a–d are longer than those in complexes 2 a–d. As a result, the nickel center is less tightly chelated by the PNCNP backbone compared with the POCOP framework. Natural population analysis (NPA) of complexes 1 a, 2 a, 1 b and 2 b indicated that the nickel center supported by a PNCNP pincer ligand is less electron‐rich. Cyclic voltammetry study of 1 a and 2 a showed that 2 a is easier to be oxidized.

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Section: Introductionsupporting

confidence: 52%

A Structure Comparison of Ni(II) Complexes Supported by PNCNP and POCOP Pincer Ligands

et al. 2020

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“…The conversions in these reactions are quantitative when monitored by NMR, and after recrystallization all compounds 7 – 18 could be isolated in good yields. We note that late transition-metal complexes bearing anionic heteroatomic ligands such as RO – or RS – are relevant for transition-metal-mediated stoichiometric and catalytic carbon–heteroatom bond-forming reactions. , Metal thiophenolate complexes are attracting increasing interest due to their likely role in biocatalytic systems such as Ni–Fe hydrogenase. − …”

Section: Resultsmentioning

confidence: 99%

A Readily Accessible Chiral NNN Pincer Ligand with a Pyrrole Backbone and Its Ni(II) Chemistry: Syntheses, Structural Chemistry, and Bond Activations

et al. 2017

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A new class of chiral C-symmetric N-donor pincer ligands, 2,5-bis(2-oxazolinyldimethylmethyl)pyrroles (PdmBox)H, was synthesized starting from the readily available ethyl 2,2-dimethyl-3-oxobutanoate (1). The synthesis of the ligand backbone was achieved by oxidative enole coupling with CuC1 followed by Paal-Knorr-type pyrrole synthesis. The corresponding protioligands (PdmBox)H (R = iPr: 5a; Ph: 5b) were obtained by condensation with amino alcohols and subsequent zinc-catalyzed cyclization. Reaction of the lithiated ligands with [NiCl(dme)] yielded the corresponding square-planar nickel(II) complexes [(PdmBox)NiCl] (6a/b). Salt metathesis of 6a with the corresponding alkali or cesium salts in acetone led to the formation of air- and moisture-stable [(PdmBox)NiX] (X = F (7), X = Br (8), X = I (9), X = N (10), X = OAc (11). Furthermore, the conversion of [(PdmBox)NiF] (7) with hydride transfer reagents such as PhSiH led to the stable hydrido species [(PdmBox)NiH] (27), the stoichiometric transformations of which were studied. Treatment of 6a with organometallic reagents such as ZnEt, PhLi, PhC≡CLi, NsLi, or (Bn)Mg(THF) gave the corresponding alkyl, alkynyl, or aryl complexes. The availability of the new nonisomerizable PdmBox pincer ligands allowed the comparative study of their ligation to square-planar complexes as helically twisted spectator ligands as opposed to the enforced planar rigidity of their iso-PmBox analogues and the way this influences the reactivity of the Ni complexes.

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“…The introduction of a direct metal–carbon bond in chelate systems leads to the formation of an organometallic complex with a metal cycle, providing additional stabilization of this bond [ 3 , 4 , 5 , 6 , 7 , 8 , 9 , 10 , 11 , 12 , 13 , 14 , 15 , 16 , 17 , 18 , 19 ]. Pincer ligands are tridentate and typically bind to a metal in a meridional fashion, forming complexes of general formula [M(E 1 YE 2 )L m ]X n ( Figure 1 ), where E 1 and E 2 are typically a neutral two-electron donor group (such as amine or phosphine group), while Y is usually represented by an anionic carbon atom of a 2,6-disubstituted aryl moiety or, less often, pyridine group; X and L are counterions and auxiliary ligands, respectively; M is metal [ 20 ].…”

Section: Introductionmentioning

confidence: 99%

Recent Advances in Chemistry of Unsymmetrical Phosphorus-Based Pincer Nickel Complexes: From Design to Catalytic Applications

et al. 2021

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Pincer complexes play an important role in organometallic chemistry; in particular, their use as homogeneous catalysts for organic transformations has increased dramatically in recent years. The high catalytic activity of such bis-cyclometallic complexes is associated with the easy tunability of their properties. Moreover, the phosphorus-based unsymmetrical pincers showed higher catalytic activity than the corresponding symmetrical analogues in several catalytic reactions. However, in modern literature, an increasing interest in the development of catalysts based on non-precious metals is observed. For example, nickel, which is an affordable and sustainable analogue of platinum and palladium, known for its low toxicity, has attracted increasing attention in the catalytic chemistry of transition metals in recent years. Thus, this mini-review is devoted to the recent advances in the chemistry of unsymmetrical phosphorus-based pincer nickel complexes, including the ligand design, the synthesis of nickel complexes and their catalytic applications.

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Recent Advances on the Chemistry of POCOP–Nickel Pincer Compounds

Cited by 45 publications

References 97 publications

A Structure Comparison of Ni(II) Complexes Supported by PNCNP and POCOP Pincer Ligands

A Structure Comparison of Ni(II) Complexes Supported by PNCNP and POCOP Pincer Ligands

A Readily Accessible Chiral NNN Pincer Ligand with a Pyrrole Backbone and Its Ni(II) Chemistry: Syntheses, Structural Chemistry, and Bond Activations

Recent Advances in Chemistry of Unsymmetrical Phosphorus-Based Pincer Nickel Complexes: From Design to Catalytic Applications

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