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The gas-phase reaction mechanisms of methylamine (MA) with the ground-state Co(+)((3)F) and Ni(+)((2)D) are theoretically investigated using density functional theory at both the B3LYP/6-311++G(d,p) and B3LYP/6-311++G(3df,2p) levels. The reactions for hydride abstraction and dehydrogenation are analyzed in terms of the topology of potential energy surfaces (PESs). Co(+) and Ni(+) perform similar roles along the isomerization processes to the final products. Hydride abstraction takes place via the key species of metal cation-methyl-H intermediate, followed by a charge transfer process before the direct dissociation of CH(2)NH(2)(+)···MH (M = Co, Ni). The enthalpies of reaction, stability of metal cation-methyl-H species, and competition between different channels account for the sequence of the hydride abstraction products: CoH < NiH < CuH. The most competitive dehydrogenation route occurs through a stepwise reaction, consisting of initial C-H activation, amino-H shift, and direct dissociation of the precursor CH(2)NHM(+)···H(2). This theoretical work sheds new light on the experimental observations and provides fundamental understanding of the reaction mechanisms of amine prototype with late first-row transition metal cations.

The gas-phase Mn(+)- and Co(+)-mediated oxidation of benzene by N(2)O has been theoretically investigated using density functional theory. The geometries and energies of all the stationary points involved are located. Two different oxidation mechanisms, i.e., mediated by M(+)(benzene) and MO(+), are taken into account. In the former catalytic cycle, benzene initially coordinates to the metal ion affording the M(+)(C(6)H(6)) adduct (M = Mn or Co), then N(2)O coordinates to the nascent benzene complex and gets activated by the metal to yield (C(6)H(6))M(+)O(N(2)). After releasing a molecular nitrogen, through the non-radical and/or O-insertion pathways, the system would be oxidized to phenol and regenerates the active catalyst M(+). This catalytic mechanism is energetically favourable, explaining the efficient Mn(+)- and Co(+)-catalyzed benzene hydroxylation observed in ion cyclotron resonance (ICR) experiments [J. Am. Chem. Soc., 1994, 116, 9565-9570]. For the alternative MO(+)-mediated oxidation mechanism, spin inversion as well as high energy barrier in the course of the N-O activation imply low reaction efficiency of the ground-state reactants, according with the ICR experiment finding that MO(+) was formed from exited M(+)*, thus both Mn(+) and Co(+) are unable to work as a catalyst in this case.

Density functional theory calculations have been carried out to survey the gas-phase reactions of allylamine with Co+. The geometries and bonding characteristics of all the stationary points involved in the reactions have been investigated at the B3LYP/6-311++G(d,p) level. Final energies are obtained by means of the B3LYP/6-311+G(2df,2pd) single-point calculations. The performance of these theoretical methods is valuated with respect to the available thermochemical data. Co+ strongly binds allylamine by forming a chelated structure in which the metal cation binds concomitantly to the two functional groups of the neutral molecule. Various mechanisms leading to the loss of NH3, NH2, C2H2, and H2 are analyzed in terms of the topology of the potential energy surface. The most favorable mechanism corresponds to the loss of NH3, through a process of C-N activation followed by a concerted beta-H shift. The accompanying NH2 elimination is also discussed. The loss of C2H2 is also favorable, through C-C activation and stepwise beta-H shift, giving Co+(NH2CH3) and Co+H(NH2CH2) as the product ions. Various possible channels for the loss of H2 are considered. The most favorable mechanism of the H2 loss corresponds to a pathway through which the metal acts as a carrier, connecting a hydrogen atom from the methylidyne group of allylamine with a hydrogen atom of the terminal methylene group. The product ion of this pathway has a tricoordinated structure in which Co+ binds to the terminal two Cs and N atoms of the NH2CH2CCH moiety.

The separation of ethylene (C2H4) from a mixture of ethane (C2H6), ethylene (C2H4), and acetylene (C2H2) at normal temperature and pressure is a significant challenge. The sieving effect of pores is powerless due to the similar molecular size and kinetic diameter of these molecules. We report a new modification method based on a stable ftw topological Zr‐MOF platform (MOF‐525). Introduction of a cyclopentadiene cobalt functional group led to new ftw‐type MOFs materials (UPC‐612 and UPC‐613), which increase the host‐guest interaction and achieve efficient ethylene purification from the mixture of hydrocarbon gases. The high performance of UPC‐612 and UPC‐613 for C2H2/C2H4/C2H6 separation has been verified by gas sorption isotherms, density functional theory (DFT), and experimentally determined breakthrough curves. This work provides a one‐step separation of the ternary gas mixture and can further serve as a blueprint for the design and construction of function‐oriented porous structures for such applications. [ABSTRACT FROM AUTHOR]

Keywords: cobalt; ethylene purification; metal-organic frameworks (MOFs); one-step purification; ternary gas mixture EN cobalt ethylene purification metal-organic frameworks (MOFs) one-step purification ternary gas mixture 11532 11532 1 05/06/21 20210510 NES 210510 B A CpCo group b was introduced in a cubic cage to generate a sphere-like force surface, thus dividing the cubic cage into two parts. Back Cover: One-step Ethylene Purification from an Acetylene/Ethylene/Ethane Ternary Mixture by Cyclopentadiene Cobalt-Functionalized Metal-Organic Frameworks (Angew. Based on the high selectivity of the CpCo group, high-purity ethylene is obtained from an acetylene/ethylene/ethane ternary mixture, as reported by Daofeng Sun et al. in their Research Article on page 11350. [Extracted from the article]

Cobalt, ethylene purification, metal-organic frameworks (MOFs), one-step purification, ternary gas mixture Keywords: cobalt; ethylene purification; metal-organic frameworks (MOFs); one-step purification; ternary gas mixture EN cobalt ethylene purification metal-organic frameworks (MOFs) one-step purification ternary gas mixture 11636 11636 1 05/06/21 20210510 NES 210510 B Eine CpCo-Einheit b wurde in einen kubischen Käfig eingeführt, um eine sphärische Kraftfläche zu erzeugen, wodurch der kubische Käfig in zwei Teile geteilt wird. Rücktitelbild: One-step Ethylene Purification from an Acetylene/Ethylene/Ethane Ternary Mixture by Cyclopentadiene Cobalt-Functionalized Metal-Organic Frameworks (Angew. [Extracted from the article]