On the dynamic nature of Mo sites for methane dehydroaromatization.

The mechanism of methane activation on Mo/HZSM-5 is not yet fully understood, despite the great interest in methane dehydroaromatization (MDA) to replace aromatics production in oil refineries. It is difficult to assess the exact nature of the active site due to fast coking. By pre-carburizing Mo/HZSM-5 with carbon monoxide (CO), the MDA active site formation was isolated from coke formation.

Revisiting Nitrogen Species in Covalent Triazine Frameworks.

Covalent triazine frameworks (CTFs) are porous organic materials promising for applications in catalysis and separation due to their high stability, adjustable porosity, and intrinsic nitrogen functionalities. CTFs are prepared by ionothermal trimerization of aromatic nitriles; however, multiple side reactions also occur under synthesis conditions, and their influence on the material properties is still poorly described. Here we report the systematic characterization of nitrogen in CTFs using X-ray photoelectron spectroscopy.

Manufacture of highly loaded silica-supported cobalt Fischer-Tropsch catalysts from a metal organic framework.

The development of synthetic protocols for the preparation of highly loaded metal nanoparticle-supported catalysts has received a great deal of attention over the last few decades. Independently controlling metal loading, nanoparticle size, distribution, and accessibility has proven challenging because of the clear interdependence between these crucial performance parameters. Here we present a stepwise methodology that, making use of a cobalt-containing metal organic framework as hard template (ZIF-67), allows addressing this long-standing challenge.

Facile Method for the Preparation of Covalent Triazine Framework coated Monoliths as Catalyst Support: Applications in C1 Catalysis.

A quasi chemical vapor deposition method for the manufacture of well-defined covalent triazine framework (CTF) coatings on cordierite monoliths is reported. The resulting supported porous organic polymer is an excellent support for the immobilization of two different homogeneous catalysts: (1) an IrCp*-based catalyst for the hydrogen production from formic acid and (2) a Pt-based catalyst for the direct activation of methane via Periana chemistry. The immobilized catalysts display a much higher activity in comparison with the unsupported CTF operated in slurry because of improved mass transport.

Complexes with nitrogen-centered radical ligands: classification, spectroscopic features, reactivity, and catalytic applications.

The electronic structure, spectroscopic features, and (catalytic) reactivity of complexes with nitrogen-centered radical ligands are described. Complexes with aminyl ([M(˙NR2)]), nitrene/imidyl ([M(˙NR)]), and nitridyl radical ligands ([M(˙N)]) are detectable and sometimes even isolable species, and despite their radical nature frequently reveal selective reactivity patterns towards a variety of organic substrates. A classification system for complexes with nitrogen-centered radical ligands based on their electronic structure leads to their description as one-electron-reduced Fischer-type systems, one-electron-oxidized Schrock-type systems, or systems with a (nearly) covalent M-N π bond.

Mechanism of cobalt(II) porphyrin-catalyzed C-H amination with organic azides: radical nature and H-atom abstraction ability of the key cobalt(III)-nitrene intermediates.

The mechanism of cobalt(II) porphyrin-catalyzed benzylic C-H bond amination of ethylbenzene, toluene, and 1,2,3,4-tetrahydronaphthalene (tetralin) using a series of different organic azides [N(3)C(O)OMe, N(3)SO(2)Ph, N(3)C(O)Ph, and N(3)P(O)(OMe)(2)] as nitrene sources was studied by means of density functional theory (DFT) calculations and electron paramagnetic resonance (EPR) spectroscopy. The DFT computational study revealed a stepwise radical process involving coordination of the azide to the metal center followed by elimination of dinitrogen to produce unusual "nitrene radical" intermediates (por)Co(III)-N(•)Y (4) [Y = -C(O)OMe, -SO(2)Ph, -C(O)Ph, -P(O)(OMe)(2)]. Formation of these nitrene radical ligand complexes is exothermic, predicting that the nitrene radical ligand complexes should be detectable species in the absence of other reacting substrates.

The radical mechanism of cobalt(II) porphyrin-catalyzed olefin aziridination and the importance of cooperative H-bonding.

The mechanism of cobalt(II) porphyrin-mediated aziridination of styrene with PhSO(2)N(3) was studied by means of DFT calculations. The computations clearly indicate the involvement of a cobalt 'nitrene radical' intermediate in the Co(II)(por)-catalyzed alkene aziridination. The addition of styrene to this species proceeds in a stepwise fashion via radical addition of the 'nitrene radical'C to the C=C double bond of styrene to form a γ-alkyl radical intermediate D.