Generation and Properties of CoI/NiI Species Stabilized by a Tetradentate Pyridylpyrazole Ligand: Crystal Structures of Dialkyl‐CoIII Complexes

Mishra, Vibha; Mishra, Hirdyesh; Mukherjee, Rabindranath

doi:10.1002/ejic.200900203

Cited by 7 publications

(2 citation statements)

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“…This transition is associated with a molar absorptivity of 5000 M –1 cm –1 . Transitions with molar absorptivities of similar magnitude have been observed for other square planar cobalt(I) complexes …”

Section: Resultssupporting

confidence: 69%

Synthesis and Reactivity of an Isolable Cobalt(I) Complex Containing a β-Diketiminate-Based Acyclic Tetradentate Ligand

2012

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A model for cobalamin was synthesized using a new monoanionic tetradentate nitrogen donor ligand; 2-(4-tolyl)-1,3-bis(2-isopropylpyridyl)propenediimine (Tol-BDI((2-pp)2)H) (1), which utilizes isopropylpyridines as pendant arms on a β-diketiminate (BDI) backbone. During the synthesis of 1, the rearrangement product, Tol-BDI((2-pp)(4-pp))H (2) was observed. Metalation of 1 with zinc iodide and cobalt chloride yielded the corresponding Tol-BDI((2-pp)2)ZnI (3) and Tol-BDI((2-pp)2)CoCl (4) complexes. The redox properties of 4 in comparison to cobalamin were examined through electrochemical studies. Electrochemical and bulk reduction of complex 4 gave a diamagnetic cobalt(I) complex, Tol-BDI((2-pp)2)Co (5). Reactivity of 5 toward C-X bonds was investigated using methyl iodide and 1-iodo-2-(trimethylsilyl)acetylene, yielding Tol-BDI((2-pp)2)Co(CH(3))I and Tol-BDI((2-pp)2)Co(C(2)Si(CH(3))(3))I respectively. Synthesis and characterization details for these complexes, including the crystal structure of 3, are reported.

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Section: Resultssupporting

confidence: 69%

Synthesis and Reactivity of an Isolable Cobalt(I) Complex Containing a β-Diketiminate-Based Acyclic Tetradentate Ligand

2012

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“…The obtained g‐values combined with the appearance of an absorption band at 535 nm in the UV/Vis is consistent with the photogeneration of a Ni I spin

1 / 2

species. Equivalent features are reported for related Ni I complexes . Spectroelectrochemical (SEC) experiments further corroborate the formation of Ni I species.…”

Section: Figuresupporting

confidence: 53%

Reductive Cyclization of Unactivated Alkyl Chlorides with Tethered Alkenes under Visible‐Light Photoredox Catalysis

et al. 2019

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The chemical inertness of abundant and commercially available alkyl chlorides precludes their widespread use as reactants in chemical transformations. Presented in this work is a metallaphotoredox methodology to achieve the catalytic intramolecular reductive cyclization of unactivated alkyl chlorides with tethered alkenes. The cleavage of strong C(sp 3 )−Cl bonds is mediated by a highly nucleophilic low‐valent cobalt or nickel intermediate generated by visible‐light photoredox reduction employing a copper photosensitizer. The high basicity and multidentate nature of the ligands are key to obtaining efficient metal catalysts for the functionalization of unactivated alkyl chlorides.

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Reductive Cyclization of Unactivated Alkyl Chlorides with Tethered Alkenes under Visible‐Light Photoredox Catalysis

et al. 2019

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The chemical inertness of abundant and commercially available alkylc hlorides precludes their widespread use as reactants in chemical transformations.P resented in this work is am etallaphotoredoxm ethodology to achieve the catalytic intramolecular reductive cyclization of unactivated alkylc hlorides with tethered alkenes.T he cleavage of strong C(sp 3 )ÀCl bonds is mediated by ah ighly nucleophilic lowvalent cobalt or nickel intermediate generated by visible-light photoredox reduction employing acopper photosensitizer.The high basicity and multidentate nature of the ligands are key to obtaining efficient metal catalysts for the functionalization of unactivated alkylc hlorides. Figure 5. Hypothetical catalytic cycle for the visible-light reductive cyclization of unactivateda lkyl chlorides with tethered alkenes. HAT = hydrogen atom abstraction, HC = homolytic cleavage.

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Generation and Properties of Co^I/Ni^I Species Stabilized by a Tetradentate Pyridylpyrazole Ligand: Crystal Structures of Dialkyl‐Co^III Complexes

Abstract: I species has been authenticated by its UV/Vis spectral feature (crystal-field transition at 901 nm and metal-to-ligand charge-transfer transition at 537 nm) and axial EPR spectrum (g ʈ = 2.27 and g Ќ = 2.08). Dark greenish blue/bright green Co I species were characterized by ab-

Cited by 7 publications

References 42 publications

Synthesis and Reactivity of an Isolable Cobalt(I) Complex Containing a β-Diketiminate-Based Acyclic Tetradentate Ligand

Synthesis and Reactivity of an Isolable Cobalt(I) Complex Containing a β-Diketiminate-Based Acyclic Tetradentate Ligand

Reductive Cyclization of Unactivated Alkyl Chlorides with Tethered Alkenes under Visible‐Light Photoredox Catalysis

Reductive Cyclization of Unactivated Alkyl Chlorides with Tethered Alkenes under Visible‐Light Photoredox Catalysis

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