Invisible Chelating Effect Exhibited between Carbodicarbene and Phosphine through π–π Interaction and Implication in the Cross-Coupling Reaction

Shih, Wei-Chih; Chiang, Yun-Ting; Wang, Qing; Wu, Ming-Chun; Yap, Glenn P. A.; Zhao, Lili; Ong, Tiow‐Gan

doi:10.1021/acs.organomet.7b00692

Cited by 23 publications

(8 citation statements)

References 51 publications

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“…1 H NMR (500 MHz, CDCl 3 , 300 K): δ (ppm): 8.80 (d, J = 8.3 Hz, 1H), 8.75 (d, J = 8.2 Hz, 1H), 8.13 (d, J = 8.05 Hz, 2H), 7.91 (d, J = 7.8 Hz, 1H), 7.85 (d, J = 8.2 Hz, 1H), 7.71–7.62 (m, 6H), 7.55 (t, J = 2.9 Hz, 1H), 2.71 (s, 3H). 1 H NMR data are consistent with the reported literature …”

Section: Methodssupporting

confidence: 91%

Ligand Steric Effects of α-Diimine Nickel(II) and Palladium(II) Complexes in the Suzuki–Miyaura Cross-Coupling Reaction

et al. 2020

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Nickel catalysts represent a low cost and environmentally friendly alternative to palladium-based catalytic systems for Suzuki–Miyaura cross-coupling (SMC) reactions. However, nickel catalysts have suffered from poor air, moisture, and thermal stabilities, especially at high catalyst loading, requiring controlled reaction conditions. In this report, we examine a family of mono- and dinuclear Ni(II) and Pd(II) complexes with a diverse and versatile α-diimine ligand environment for SMC reactions. To evaluate the ligand steric effects, including the bite angle in the reaction outcomes, the structural variation of the complexes was achieved by incorporating iminopyridine- and acenaphthene-based ligands. Moreover, the impact of substrate bulkiness was investigated by reacting various aryl bromides with phenylboronic acid, 2-naphthylboronic acid, and 9-phenanthracenylboronic acid. Yields were the best with the dinuclear complex, being nearly quantitative (93–99%), followed by the mononuclear complexes, giving yields of 78–98%. Consequently, α-diimine-based ligands have the potential to deliver Ni-based systems as sustainable catalysts in SMC.

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Section: Methodssupporting

confidence: 91%

Ligand Steric Effects of α-Diimine Nickel(II) and Palladium(II) Complexes in the Suzuki–Miyaura Cross-Coupling Reaction

et al. 2020

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“…In fact, they suggested that such molecules should be depicted as two carbenes coordinated to a carbon(0) center . This led to them being referred to as carbodicarbenes (CDCs). − Shortly after this study, support for this assignment was provided by close agreement between the calculated structural parameters and those observed in the X-ray structures of an isolated bent allene and of a gold(I) complex of tetra(dimethylamino)allene ( 1 and 2 ; Figure ), which were reported by Bertrand et al and Fürstner et al, respectively.…”

Section: Introductionsupporting

confidence: 60%

Carbodicarbene Ligand Redox Noninnocence in Highly Oxidized Chromium and Cobalt Complexes

Chan

Ang

Gupta³

et al. 2020

Inorg. Chem.

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Carbodicarbenes (CDCs) possess two lone pairs of electrons on their central carbone C atom (C carbone ). Coordination to a transition metal via a σ bond leaves one pair of electrons with appropriate symmetry for π donation to the metal. However, the high energy of the latter also renders the CDC ligand potentially redox-active. Herein, we explore these alternatives in the redox series [Cr(L) 2 ] n+ and [Co(L) 2 ] n+ (n = 2−5), where L is a tridentate ligand comprised of a central CDC and two flanking pyridine donors. To this end, all members of both redox series were synthesized and their electronic structures were investigated by using a combination of 1 H NMR, Evans' NMR, IR, UV−vis, and EPR spectroscopies, SQUID magnetometry, X-ray crystallography, and density functional theory studies. Whereas [Co II (L) 2 ] 2+ is a straightforward low-spin (S = 1 / 2 ) cobalt(II) complex, the corresponding chromium complex was found to feature an electronic structure that is intermediate between the two limiting resonance forms [Cr III (L •− )(L)] 2+ and [Cr II (L) 2 ] 2+ . In the case of the tri-, tetra-, and pentacationic complexes, the qualitatively identical electronic structures [M III (L) 2 ] 3+ , [M III (L •+ )(L)] 4+ , and [M III (L •+ ) 2 ] 5+ were observed for both metals. Thus, the metal ions retain a 3+ oxidation state throughout, and the higher redox states contain oxidized ligands. The majority of the unpaired spin on the cation radical ligands was calculated to be localized in π-symmetry orbitals on the coordinated C carbone atoms. Analogous behavior was previously reported for the corresponding iron redox series and, as such, redox noninnocence in oxidized CDC and, more broadly, carbone complexes is likely widely accessible.

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“…Suzuki–Miyaura cross coupling was also performed using complexes [Pd( 589- i Pr )(PR 3 )Cl 2 ] (R = Ph, p -Tol) (Scheme ). These two complexes were readily synthesized by addition of carbodicarbene 589- i Pr to the corresponding palladium triarylphosphine dichloride complex. X-ray diffraction analysis showed an unusual trans arrangement, which could be explained by intramolecular π–π stacking between one aromatic ring of the phosphine and the benzimidazole ring of ligand 589- i Pr , with centroid-centroid distances of 3.25 Å (R = Ph) and 3.30 Å (R = p -Tol).…”

Section: Geminal Dianions Of Type III (A and B: Cationic Fragments)mentioning

confidence: 99%

Geminal Dianions Stabilized by Main Group Elements

2019

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This review is dedicated to the chemistry of stable and isolable species that bear two lone pairs at the same C center, i.e. geminal dianions, stabilized by main group elements. Three cases can thus be considered: the gem dilithio derivative, for which the two substituents at C are neutral, the ylidiide derivatives, for which one substituent is neutral while the other is charged, and finally the geminal bisylides, for which the two substituents are positively charged. In this review the syntheses and electronic structures of the geminal dianions are presented, followed by the studies dedicated to their reactivity toward organic substrates and finally to their coordination chemistry and applications. Reactivity of doubleylides towards organic compounds. 4.4. Coordination chemistry of double ylides to metallic species. 4.4.1. Coordination to Group 2 Metals. 4.4.2. Coordination to Actinides: Uranium Complexes 4.4.3. Coordination to Group 4 Metals: Zirconium Complexes 4.4.4. Coordination to Group 6 Metals: Tungsten Complexes 4.4.5. Coordination to Group 7 Metals: Manganese and Rhenium Complexes 4.4.6. Coordination to Group 8 Metals: Iron Complexes 4.4.7. Coordination to Group 9 Metals: Rhodium and Iridium Complexes 4.4.8. Coordination to Group 10 Metals 4.4.9. Coordination to Group 11 (Coinage) Metals 4.4.10. Coordination to Group 12 Metals 4.5. Reactivity of double ylides towards main group elements. 4.5.1. Group 13 4.5.2. Group 14 4.5.3. Group 15 4.5.4. Group 16 4.5.5. Group 17 4.6. Carbodicarbenes 4.6.1. Synthesis 4.6.2. Reactivity 4.6.3. Coordination chemistry 4.6.4. Reactivity with main group elements 5. Conclusion 6. Acknowledgements 7. References lengths in complexes [(7)Mg(THF)] 2 and [(14)Mg(THF) 3 ] at 2.156(5)Å and 2.113(4)Å resp. are as expectedly significantly shorter than the ones measured in the dimers [(6a)Mg] 2 and [(10)Mg] 2 at 2.225(2)Å (av.) and 2.267(3)Å (av.). Electronic structureThe question of the nature of the bond between the AE metal and C was addressed. Harder et al.performed a DFT study first on models of [(6a)Ca] 2 and [(6f)Ca] where H atoms were considered in place of the real phenyl groups at P and groups (SiMe 3 and Ar resp.) at N. 49 In the case of the monomeric complex [(6f)Ca], the solvent molecules were not taken into account. Not surprising in light of the difference of electronegativity of the elements, the charge at C varied between -1.623 (monomer) and -1.847 (dimer) whereas charge at Ca varied between +1.760 (monomer) and +1.821 (dimer). The Ca-C bond was thus described as highly ionic. The calculations with the full dimeric system were carried out, and a slightly reduced charge was calculated at C (-1.778). The NPA charges were also compared to the ones in neutral 6aH 2 and the [Ca(6aH) 2 ] complex. Expectedly the charge at C goes from -1.079 to -1.409 to -1.778 (in 6aH2, [Ca(6aH) 2 ], [Ca(6a)] 2 resp.). The charge at N also increases (-1.474 to -1.580 to -1.665 resp.) upon deprotonation at C. Conversely, the charge at P varies but to a small extent (+1.747 to +1.727 to +1.7...

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Invisible Chelating Effect Exhibited between Carbodicarbene and Phosphine through π–π Interaction and Implication in the Cross-Coupling Reaction

Cited by 23 publications

References 51 publications

Ligand Steric Effects of α-Diimine Nickel(II) and Palladium(II) Complexes in the Suzuki–Miyaura Cross-Coupling Reaction

Ligand Steric Effects of α-Diimine Nickel(II) and Palladium(II) Complexes in the Suzuki–Miyaura Cross-Coupling Reaction

Carbodicarbene Ligand Redox Noninnocence in Highly Oxidized Chromium and Cobalt Complexes

Geminal Dianions Stabilized by Main Group Elements

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