N–H cleavage as a route to new pincer complexes of high-valent rhenium

2016 ◽  
Vol 45 (46) ◽  
pp. 18532-18540 ◽  
Author(s):  
Alex J. Kosanovich ◽  
Wei-Chun Shih ◽  
Rodrigo Ramírez-Contreras ◽  
Oleg. V. Ozerov
Keyword(s):  
Pincer Complexes ◽  
Pincer Ligand ◽  
Oxo Complexes ◽  
High Valent ◽  
Rhenium Oxo Complexes

Rhenium oxo complexes of a new PNN (phosphine-amido-amido) pincer ligand display rotameric isomerism and can be reversibly protonated.

Effect of Hydrated Metal Salts on the Coordination Product of Cobalt(II) halide and PNP Type Ligand, 2,6-bis(di-tertbutylphosphinomethyl) pyridine

2018 ◽  
Author(s):  
Tasneem Siddiquee ◽  
Abdul Goni
Keyword(s):  
Metal Salts ◽  
Molar Ratio ◽  
Pincer Complexes ◽  
Asymmetric Unit ◽  
X Ray Diffraction ◽  
Pincer Ligand ◽  
Tetrahedral Geometry ◽  
X Ray ◽  
Distorted Tetrahedral Geometry ◽  
Cobalt Center

Chemical treatment of CoX<sub>2</sub><b><sup>. </sup></b>6H<sub>2</sub>O (X = Cl, Br, I) with the potentially tridentate PNP pincer ligand 2,6-bis(di-<i>tert</i>-butylphosphinomethyl)pyridine in 1:1 molar ratio results in cobalt(II) halide-PNP pincer complexes. The effect of the hydrated metal source on molecular structure and geometry of the complexes was studied by single crystal X-ray diffraction analysis. The complexes are neutral and the cobalt center adopts a penta-coordinate system with potential atropisomerization. Within the unit cell there are two distinct molecules per asymmetric unit. One of the two phosphorus atoms in the PNP ligand was observed to be partially oxidized to phosphinoxide. Disorder in the structure reflects a mixture of square pyramidal and distorted tetrahedral geometry.

scholarly journals Cobalt Pincer Complexes in Catalytic C–H Borylation: The Pincer Ligand Flips Rather Than Dearomatizes

ACS Catalysis ◽  
2018 ◽  
Vol 8 (11) ◽  
pp. 10606-10618 ◽  
Author(s):  
Haixia Li ◽  
Jennifer V. Obligacion ◽  
Paul J. Chirik ◽  
Michael B. Hall
Keyword(s):  
Pincer Complexes ◽  
Pincer Ligand

scholarly journals Quantum Mechanistic Studies of the Oxidation of Ethylene by Rhenium Oxo Complexes

2021 ◽  
Vol 2021 ◽  
pp. 1-11
Author(s):  
Emmanuel Adu Fosu ◽  
Collins Obuah ◽  
Louis Hamenu ◽  
Albert Aniagyei ◽  
Michael Kojo Ainooson ◽  
...  
Keyword(s):  
Potential Energy ◽  
Potential Energy Surfaces ◽  
Frontier Molecular Orbital ◽  
Molecular Orbital Calculations ◽  
Oxo Complexes ◽  
Reaction Energies ◽  
Energy Surfaces ◽  
Rhenium Oxo Complexes ◽  
Epoxidation Catalyst ◽  
Addition Pathway

Transition-metal-mediated oxygen transfer reactions are of importance in both industry and academia; thus, a series of rhenium oxo complexes of the type ReO3L (L = O−, Cl−, F−, OH−, Br−, I−) and their effects as oxidation catalysts on ethylene have been studied. The activation and reaction energies for the addition pathways involving multiple spin states (singlet and triplet) have been computed. In all cases, structures on the singlet potential energy surfaces showed higher stability compared to their counterparts on the triplet potential energy surfaces (PESs). Frontier Molecular Orbital calculations show electrons flow from the HOMO of ethylene to the LUMO of rhenium for all complexes studied except ReO4− where the reverse case occurs. In the reaction between ReO3L (L = O−, Cl−, F−, OH−, Br−, and I−) and ethylene, the concerted [3 + 2] addition pathway on the singlet PES leading to the formation of dioxylate intermediate is favored over the [2 + 2] addition pathway leading to the formation of a metallaoxetane intermediate and subsequent rearrangement to the dioxylate. The activation and the reaction energies for the formation of the dioxylate on the singlet PES for the ligands studied followed the order O− > OH− > I− > F− > Br− > Cl− and O− > OH− > F− > I− > Br− > Cl−, respectively. Furthermore, the activation and the reaction energies for the formation of the metallaoxetane intermediate increase in the order O− > OH− > I− > Br− > Cl− > F− and O− > Br− > I− > Cl− > OH− > F−, respectively. The subsequent rearrangement of the metallaoxetane intermediate to the dioxylate is only feasible in the case of ReO4−. Of all the complexes studied, the best dioxylating catalyst is ReO3Cl (singlet surface) and the best epoxidation catalyst is ReO3F (singlet surface).

scholarly journals A Kinetic Study on the Efficient Formation of High-Valent Mn(TPPS)-oxo Complexes by Various Oxidants

Catalysts ◽  
2020 ◽  
Vol 10 (6) ◽  
pp. 610
Author(s):  
Magdalena Procner ◽  
Łukasz Orzel ◽  
Grażyna Stochel ◽  
Rudi van Eldik
Keyword(s):  
Transition Metal Complexes ◽  
Peracetic Acid ◽  
Research Work ◽  
Sodium Perborate ◽  
Oxidation Reactions ◽  
Oxo Complexes ◽  
Significant Research ◽  
Order Of Magnitude ◽  
High Valent ◽  
Harmful Effects

New, more efficient methods of wastewater treatment, which will limit the harmful effects of textile dyes on the natural environment, are still being sought. Significant research work suggests that catalysts based on transition metal complexes can be used in efficient and environmentally friendly processes. In this context, a number of compounds containing manganese have been investigated. A suitable catalyst should have the capacity to activate a selected oxidant or group of oxidants, in order to be used in industrial oxidation reactions. In the present study we investigated the ability of MnIII(TPPS), where TPPS = 5,10,15,20-tetrakis(4-sulphonatophenyl)-21H,23H-porphyrine, to activate five different oxidants, namely hydrogen peroxide, peracetic acid, sodium hypochlorite, potassium peroxomonosulfate and sodium perborate, via the formation of high valent Mn(TPPS)-oxo complexes. Kinetic and spectroscopic data showed that the oxidation process is highly pH dependent and is strongly accelerated by the presence of carbonate in the reaction mixture for three of the five oxidizing agents. The highest efficiency for the oxidation of MnIII(TPPS) to high-valent Mn(TPPS)-oxo complexes, was found for peracetic acid at pH ≈ 11 in 0.5 M carbonate solution, which is at least an order of magnitude higher than the rate constants found for the other tested oxidants under similar conditions.

Monooxygenase models: Structure and reactivity of a series of high valent oxo complexes of Cr, Mn, and Ru.

1993 ◽  
Vol 51 (1-2) ◽  
pp. 293
Author(s):  
Nathanael L.P. Fackler ◽  
F.M. MacDonnell ◽  
Thomas V. O'Halloran
Keyword(s):  
Oxo Complexes ◽  
High Valent

Influence of Ligand Architecture on Oxidation Reactions by High-Valent Nonheme Manganese Oxo Complexes Using Water as a Source of Oxygen

2014 ◽  
Vol 54 (7) ◽  
pp. 2095-2099 ◽  
Author(s):  
Prasenjit Barman ◽  
Anil Kumar Vardhaman ◽  
Bodo Martin ◽  
Svenja J. Wörner ◽  
Chivukula V. Sastri ◽  
...  
Keyword(s):  
Oxidation Reactions ◽  
Oxo Complexes ◽  
High Valent

Mechanistic Insight into Alcohol Oxidation by High-Valent Iron-Oxo Complexes of Heme and Nonheme Ligands

2005 ◽  
Vol 44 (27) ◽  
pp. 4235-4239 ◽  
Author(s):  
Na Young Oh ◽  
Yumi Suh ◽  
Mi Joo Park ◽  
Mi Sook Seo ◽  
Jinheung Kim ◽  
...  
Keyword(s):  
Alcohol Oxidation ◽  
Oxo Complexes ◽  
Mechanistic Insight ◽  
High Valent ◽  
Insight Into
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