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Joseph L Templeton - One of the best experts on this subject based on the ideXlab platform.

  • exploring oxidation of half sandwich rhodium complexes oxygen atom insertion into the rhodium Carbon Bond of κ2 coordinated 2 phenylpyridine
    Organometallics, 2014
    Co-Authors: Christopher R Turlington, James Morris, Peter S White, William W Brennessel, William D Jones, Maurice Brookhart, Joseph L Templeton
    Abstract:

    The reactions of oxygen atom transfer reagents with Rh(Cp*) complexes, each with a bidentate ligand and an accessible coordination site, are described (Cp* = η5-pentamethylcyclopentadienyl). When [Rh(Cp*)(phpy)(NCArF)][B(ArF)4] (1, phpy = 2-phenylene-κC1′-pyridine-κN, NCArF = 3,5-bis(trifluoromethyl)benzonitrile, B(ArF)4 = tetrakis[3,5-bis(trifluoromethyl)phenyl]borate) was treated with the soluble oxygen atom transfer reagent 2-tert-butylsulfonyliodosylbenzene (sPhIO), oxygen atom insertion into the rhodium–Carbon Bond of coordinated phpy was observed. This resulted in the formation of a κ2 2-(2-pyridyl)phenoxide ligand. Following insertion to form a new bidentate ligand, a second equivalent of sPhIO, acting as a neutral, two-electron donor ligand, coordinated to the rhodium center through the iodosyl oxygen. Over time, the sPhIO ligand dissociates and dimerization occurs to generate a phenoxide-bridged dinuclear species. The 2-(2-pyridyl)phenoxide ligand could be protonated and cleaved from the mononucl...

  • Exploring Oxidation of Half-Sandwich Rhodium Complexes: Oxygen Atom Insertion into the Rhodium–Carbon Bond of κ2‑Coordinated 2‑Phenylpyridine
    2014
    Co-Authors: Christopher R Turlington, James Morris, Peter S White, William W Brennessel, William D Jones, Maurice Brookhart, Joseph L Templeton
    Abstract:

    The reactions of oxygen atom transfer reagents with Rh­(Cp*) complexes, each with a bidentate ligand and an accessible coordination site, are described (Cp* = η5-penta­methyl­cyclo­pentadienyl). When [Rh­(Cp*)­(phpy)­(NCArF)]­[B­(ArF)4] (1, phpy = 2-phenylene-κC1′-pyridine-κN, NCArF = 3,5-bis­(trifluoro­methyl)­benzonitrile, B­(ArF)4 = tetrakis­[3,5-bis­(trifluoro­methyl)­phenyl]­borate) was treated with the soluble oxygen atom transfer reagent 2-tert-butyl­sulfonyl­iodosyl­benzene (sPhIO), oxygen atom insertion into the rhodium–Carbon Bond of coordinated phpy was observed. This resulted in the formation of a κ2 2-(2-pyridyl)­phenoxide ligand. Following insertion to form a new bidentate ligand, a second equivalent of sPhIO, acting as a neutral, two-electron donor ligand, coordinated to the rhodium center through the iodosyl oxygen. Over time, the sPhIO ligand dissociates and dimerization occurs to generate a phenoxide-bridged dinuclear species. The 2-(2-pyridyl)­phenoxide ligand could be protonated and cleaved from the mononuclear rhodium-(sPhIO) adduct by treating with a carboxylic acid (pivalic acid) at room temperature. In addition, when rhodium complex 1 was treated with excess phpy (14 equiv), hydrogen peroxide, and acetic acid, 5 equiv of 2-(2-pyridyl)­phenol formed. Deactivation of the organometallic species, probably due to oxidative degradation of Cp*, severely limited this catalysis

Han Sen Soo - One of the best experts on this subject based on the ideXlab platform.

  • spectroscopic characterization and mechanistic studies on visible light photoredox Carbon Carbon Bond formation by bis arylimino acenaphthene copper photosensitizers
    ACS Catalysis, 2018
    Co-Authors: Lisa Jiaying Tan, Yoke Tin Chai, Rakesh Ganguly, Edwin K L Yeow, Han Sen Soo
    Abstract:

    Currently, the most popular molecular photosensitizers used for synthetic organic chemistry and energy applications are still the noble-metal-based ruthenium and iridium complexes that usually require expensive metal and ligand precursors. In contrast, bis(arylimino)acenaphthene (Ar-BIAN) is an established redox noninnocent π-accepting ligand that is easily assembled in one condensation step from affordable and commercially available precursors. Herein, we have developed a series of Ar-BIAN CuI complexes as visible-light-harvesting photosensitizers. Notably, one of these panchromatic, homoleptic Ar-BIAN CuI complexes exhibits a radiative recombination lifetime that is longer than diffusion-controlled reactions, as observed by time-correlated single-photon counting spectroscopy. Ar-BIAN CuI facilitates visible-light-promoted atom-transfer radical addition reactions via Carbon–Carbon Bond formation with CBr3 radicals in good yields of up to 75%. Steady-state and transient absorption spectroscopic measuremen...

  • Spectroscopic Characterization and Mechanistic Studies on Visible Light Photoredox Carbon–Carbon Bond Formation by Bis(arylimino)acenaphthene Copper Photosensitizers
    2018
    Co-Authors: Lisa Jiaying Tan, Yoke Tin Chai, Rakesh Ganguly, Edwin K L Yeow, Han Sen Soo
    Abstract:

    Currently, the most popular molecular photosensitizers used for synthetic organic chemistry and energy applications are still the noble-metal-based ruthenium and iridium complexes that usually require expensive metal and ligand precursors. In contrast, bis­(arylimino)­acenaphthene (Ar-BIAN) is an established redox noninnocent π-accepting ligand that is easily assembled in one condensation step from affordable and commercially available precursors. Herein, we have developed a series of Ar-BIAN CuI complexes as visible-light-harvesting photosensitizers. Notably, one of these panchromatic, homoleptic Ar-BIAN CuI complexes exhibits a radiative recombination lifetime that is longer than diffusion-controlled reactions, as observed by time-correlated single-photon counting spectroscopy. Ar-BIAN CuI facilitates visible-light-promoted atom-transfer radical addition reactions via Carbon–Carbon Bond formation with CBr3 radicals in good yields of up to 75%. Steady-state and transient absorption spectroscopic measurements, together with spectroelectrochemical experiments and intermediate isolation studies, were performed to obtain insights into this photoredox catalysis and provide guidelines for the general deployment of Ar-BIAN CuI photosensitizers in synthetic organic chemistry and renewable energy applications

Guangbin Dong - One of the best experts on this subject based on the ideXlab platform.

  • cut and sew transformations via transition metal catalyzed Carbon Carbon Bond activation
    ACS Catalysis, 2017
    Co-Authors: Penghao Chen, Brent Allen Billett, Tatsuhiro Tsukamoto, Guangbin Dong
    Abstract:

    The transition-metal-catalyzed “cut and sew” transformation has recently emerged as a useful strategy for preparing complex molecular structures. After oxidative addition of a transition metal into a Carbon–Carbon Bond, the resulting two Carbon termini can be both functionalized in one step via a following migratory insertion and reductive elimination with unsaturated units, such as alkenes, alkynes, allenes, CO, and polar multiple Bonds. Three- or four-membered rings are often employed as reaction partners due to their high ring strains. The participation of nonstrained structures generally relies on cleavage of a polar Carbon–CN Bond or assistance of a directing group.

Ledendecke Marc - One of the best experts on this subject based on the ideXlab platform.

  • Transition Metal-Carbon Bond Enthalpies as Descriptor for the Electrochemical Stability of Transition Metal Carbides in Electrocatalytic Applications
    Electrochemical Society, 2020
    Co-Authors: Göhl Daniel, Rueß Holge, Pande Marc, Zeradjani Aleksanda, Mayrhofer, Karl J.j., Schneider, Joche M., Erbe Andreas, Ledendecke Marc
    Abstract:

    Transition metal carbides are used for various applications such as hard coating, heterogeneous catalysis, catalyst support material or coatings in fuel cell applications. However, little is known about the stability of their electrochemically active surface in aqueous electrolytes. Herein, the transition metal—Carbon Bond enthalpy is proposed as stability criterion for various transition metal carbides. The basis is an oxidation mechanism where the rate determining step is the metal—Carbon Bond cleavage under acidic conditions which was supported by a detailed corrosion study on hexagonal tungsten carbide. In situ flow cell measurements that were coupled to an inductively coupled plasma mass spectrometer corroborated experimentally the linear dependency of the oxidation overpotential on the transition metal—Carbon Bond enthalpy. The proposed model allows the estimation of the activation overpotential for electrochemical carbide oxidation resulting in a maximized stabilization for carbides in the 4th group (Ti, Zr, Hf). Together with the calculated thermodynamic oxidation potentials, TiC and VC exhibit the highest experimental oxidation potentials (0.85 VRHE). The model can be used for preselecting possible carbide materials for various electrochemical reactions

Christopher R Turlington - One of the best experts on this subject based on the ideXlab platform.

  • exploring oxidation of half sandwich rhodium complexes oxygen atom insertion into the rhodium Carbon Bond of κ2 coordinated 2 phenylpyridine
    Organometallics, 2014
    Co-Authors: Christopher R Turlington, James Morris, Peter S White, William W Brennessel, William D Jones, Maurice Brookhart, Joseph L Templeton
    Abstract:

    The reactions of oxygen atom transfer reagents with Rh(Cp*) complexes, each with a bidentate ligand and an accessible coordination site, are described (Cp* = η5-pentamethylcyclopentadienyl). When [Rh(Cp*)(phpy)(NCArF)][B(ArF)4] (1, phpy = 2-phenylene-κC1′-pyridine-κN, NCArF = 3,5-bis(trifluoromethyl)benzonitrile, B(ArF)4 = tetrakis[3,5-bis(trifluoromethyl)phenyl]borate) was treated with the soluble oxygen atom transfer reagent 2-tert-butylsulfonyliodosylbenzene (sPhIO), oxygen atom insertion into the rhodium–Carbon Bond of coordinated phpy was observed. This resulted in the formation of a κ2 2-(2-pyridyl)phenoxide ligand. Following insertion to form a new bidentate ligand, a second equivalent of sPhIO, acting as a neutral, two-electron donor ligand, coordinated to the rhodium center through the iodosyl oxygen. Over time, the sPhIO ligand dissociates and dimerization occurs to generate a phenoxide-bridged dinuclear species. The 2-(2-pyridyl)phenoxide ligand could be protonated and cleaved from the mononucl...

  • Exploring Oxidation of Half-Sandwich Rhodium Complexes: Oxygen Atom Insertion into the Rhodium–Carbon Bond of κ2‑Coordinated 2‑Phenylpyridine
    2014
    Co-Authors: Christopher R Turlington, James Morris, Peter S White, William W Brennessel, William D Jones, Maurice Brookhart, Joseph L Templeton
    Abstract:

    The reactions of oxygen atom transfer reagents with Rh­(Cp*) complexes, each with a bidentate ligand and an accessible coordination site, are described (Cp* = η5-penta­methyl­cyclo­pentadienyl). When [Rh­(Cp*)­(phpy)­(NCArF)]­[B­(ArF)4] (1, phpy = 2-phenylene-κC1′-pyridine-κN, NCArF = 3,5-bis­(trifluoro­methyl)­benzonitrile, B­(ArF)4 = tetrakis­[3,5-bis­(trifluoro­methyl)­phenyl]­borate) was treated with the soluble oxygen atom transfer reagent 2-tert-butyl­sulfonyl­iodosyl­benzene (sPhIO), oxygen atom insertion into the rhodium–Carbon Bond of coordinated phpy was observed. This resulted in the formation of a κ2 2-(2-pyridyl)­phenoxide ligand. Following insertion to form a new bidentate ligand, a second equivalent of sPhIO, acting as a neutral, two-electron donor ligand, coordinated to the rhodium center through the iodosyl oxygen. Over time, the sPhIO ligand dissociates and dimerization occurs to generate a phenoxide-bridged dinuclear species. The 2-(2-pyridyl)­phenoxide ligand could be protonated and cleaved from the mononuclear rhodium-(sPhIO) adduct by treating with a carboxylic acid (pivalic acid) at room temperature. In addition, when rhodium complex 1 was treated with excess phpy (14 equiv), hydrogen peroxide, and acetic acid, 5 equiv of 2-(2-pyridyl)­phenol formed. Deactivation of the organometallic species, probably due to oxidative degradation of Cp*, severely limited this catalysis