dioxygen ͉ compound I ͉ peroxidase ͉ peroxygenase ͉ chlorite

The properties of catenated nitrogen molecules, molecules containing internal chains of bonded nitrogen atoms, is of fundamental scientific interest in chemical structure and bonding, as nitrogen is uniquely situated in the periodic table to form kinetically stable compounds often with chemically stable N–N bonds but which are thermodynamically unstable in that the formation of stable multiply bonded N2 is usually thermodynamically preferable. This unique placement in the periodic table makes catenated nitrogen compounds of interest for development of high-energy-density materials, including explosives for defense and construction purposes, as well as propellants for missile propulsion and for space exploration. This review, designed for a chemical audience, describes foundational subjects, methods, and metrics relevant to the energetic materials community and provides an overview of important classes of catenated nitrogen compounds ranging from theoretical investigation of hypothetical molecules to the practical application of real-world energetic materials. The review is intended to provide detailed chemical insight into the synthesis and decomposition of such materials as well as foundational knowledge of energetic science new to most chemists.

We investigated the dependence of the electrocatalytic activity for the oxygen evolution reaction (OER) on the interlayer distance of five compositionally distinct layered manganese oxide nanostructures. Each individual electrocatalyst was assembled with a different alkali metal intercalated between two nanosheets (NS) of manganese oxide to form a bilayer structure. Manganese oxide NS were synthesized via the exfoliation of a layered material, birnessite. Atomic force microscopy was used to determine the heights of the bilayer catalysts. The interlayer spacing of the supported bilayers positively correlates with the size of the alkali cation: NS/Cs/NS > NS/Rb/NS > NS/K/NS > NS/Na/NS > NS/Li/NS. The thermodynamic origins of these bilayer heights were investigated using molecular dynamics simulations. The overpotential (η) for the OER correlates with the interlayer spacing; NS/Cs/NS has the lowest η (0.45 V), while NS/Li/NS exhibits the highest η (0.68 V) for OER at a current density of 1 mA/cm. Kinetic parameters (η and Tafel slope) associated with NS/Cs/NS for the OER were superior to that of the bulk birnessite phase, highlighting the structural uniqueness of these nanoscale assemblies.

Catalytic deoxygenation of epoxides and diols is underdeveloped. This reaction is appealing in the context of making value-added organics from biomass. Methyltrioxorhenium (MTO) catalyzes the conversion of epoxides and vicinal diols to olefins with dihydrogen (H(2)) as the reductant under reasonably mild conditions (150 degrees C and 80-300 psi). The only reaction byproduct is water. The reaction is selective for cis cyclic diols, signaling a mechanism of alkene extrusion from a coordinated epoxide via a metallaoxetane intermediate.

The reaction of Arl=NTs (Ar = 2-(tert-butylsulfonyl)benzene and Ts = p-toluenesulfonyl) and (tpfc)Mn (tpfc=5,10,15-tris(pentafluorophenyl)corrole), 1, affords the high-valent (tpfc)MnV=NTs, 2, on stopped-flow time scale. The reaction proceeds via the adduct [(tpfc)MnIII(ArINTs)], 3, with formation constant K3 = (10 +/- 2) x 10(3) L mol-1. Subsequently, 3 undergoes unimolecular group transfer to give complex 2 with the rate constant k4 = 0.26 +/- 0.07 s-1 at 24.0 degrees C. The complex (tpfc)Mn catalyzes [NTs] group transfer from ArINTs to styrene substrates with low catalyst loading and without requirement of excess olefin. The catalytic aziridination reaction is most efficient in benzene because solvents such as toluene undergo a competing hydrogen atom transfer (HAT) reaction resulting in H2NTs and lowered aziridine yields. The high-valent manganese imido complex (tpfc)Mn=NTs does not transfer its [NTs] group to styrene. Double-labeling experiments with ArINTs and ArINTstBu (TstBu = (p-tert-butylphenyl)sulfonyl) establish the source of [NR] transfer as a "third oxidant", which is an adduct of Mn(V) imido, [(tpfc)Mn(NTstBu)(ArINTs)](4). Formation of this oxidant is rate limiting in catalysis.