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A comprehensive density functional theory (DFT) investigation of the catalytic oxidation of NO to NO2 on neutral and charged [Pt2]0,± dimers has been considered employing M06L/def2TZVP level of theory. Single as well as co‐adsorption energies of NO and O2 molecules suggest that the traditional Langmuir Hinshelwood (LH) mechanism and less explored termolecular Eley–Rideal (TER) and termolecular Langmuir Hinshelwood (TLH) mechanisms, are suitable for a full catalytic reaction pathway in which two NO molecules are converted to two NO2 molecules, initiated by an activated O2 molecule. Activation barrier reveals that the TER mechanism is found to be more reliable in converting two NO molecules into two NO2 molecules on [Pt2]¯ dimer. In addition to shedding light on the intrinsic characteristics of Pt2 dimers, the study will serve as a benchmark for investigating the oxidation process of NO to NO2 utilizing models of termolecular chemical processes. [ABSTRACT FROM AUTHOR]

A comprehensive density functional theory (DFT) investigation of the catalytic oxidation of NO to NO2 on neutral and charged [Pt2]0,± dimers has been considered employing M06L/def2TZVP level of theory. Single as well as co‐adsorption energies of NO and O2 molecules suggest that the traditional Langmuir Hinshelwood (LH) mechanism and less explored termolecular Eley–Rideal (TER) and termolecular Langmuir Hinshelwood (TLH) mechanisms, are suitable for a full catalytic reaction pathway in which two NO molecules are converted to two NO2 molecules, initiated by an activated O2 molecule. Activation barrier reveals that the TER mechanism is found to be more reliable in converting two NO molecules into two NO2 molecules on [Pt2]¯ dimer. In addition to shedding light on the intrinsic characteristics of Pt2 dimers, the study will serve as a benchmark for investigating the oxidation process of NO to NO2 utilizing models of termolecular chemical processes. [ABSTRACT FROM AUTHOR]

The partial oxidation of methane to methanol using cationic Pd2 dimers is investigated by employing density functional theory (DFT) method. We used B3PW91 functional for geometry optimization, and frequency calculations of all species involved in [Pd2]++O2+2CH4 reaction. Furthermore, a density‐fitting triple zeta valence with single‐polarization (def2TZVP) is used in the calculation to determine the atomic orbitals of the atoms. We oxidized Pd2+ to [Pd2O2]+ using O2 and performed possible partial oxidation of methane to methanol on [Pd2O2]+ and [Pd2O]+ and explored various intermediates and transition states on the potential energy surface (PES) diagram. From Potential Energy Surface (PES) analysis, it is found that the [Pd2O2]+ in doublet spin state multiplicity (SM=2) following radical mechanism is the more preferred pathway for methane to methanol conversion. [ABSTRACT FROM AUTHOR]

A tetranuclear Zn (Zn4) complex was selected for immobilization on novel layered Hiroshima -University Silicate (HUS)-7. Modification of HUS-7 was carried out using a sulfopropylsilyl agent followed by Zn4 complex incorporation. The structural investigation of this organic-inorganic, hybrid layered HUS-7 material was performed using various measurements to confirm the tethering of guest molecules. The modified HUS-7 was used as a catalyst for two different catalytic epoxide ring opening reactions, yielding two different regioisomeric products (b-amino alcohols). Theoretical energy calculations were performed for the pure Zn4 complex, substrate, nucleophile, intermediates and products to check the stability of the regioisomer for the morpholine system. The catalyst was found to be highly active for both the reaction systems with reusability up to the fourth cycle supporting the significance of the proposed functionalization. Furthermore, investigation of structural changes of the spent catalyst was also carried out. [ABSTRACT FROM AUTHOR]

Present manuscript represents the DFT studies on the oxidation reaction of camphene initiated by OH radical and fate of product radicals using M06-2X functional along with 6-31+G(d,p) basis set. Intrinsic reaction calculation is done for transition states involving OH-addition reactions which proceed via reaction complexes proceeding to the formation of transition states. The rate constant calculated by using canonical transition state theory at 298 K and 1 atm is found to be 5.67 × 10 cm molecule s which is in good agreement with the experimental rate constant. The atmospheric lifetime of the titled molecule has also been reported in our work. [ABSTRACT FROM AUTHOR]

A dual-level quantum chemical calculations have been carried out on the initiation of night-time degradation of 2-chloroethyl ethyl ether (CH3CH2OCH2CH2Cl) via H-abstraction by NO3 radical. Within the scope of density functional theory, the electronic structure of all the species involved in the titled reaction has been optimized at M06-2X functional along with 6-31G(d,p) basis set. A higher level of couple cluster CCSD(T) method in conjunction with 6-311G(d,p) basis set has been used for the refined energy of the species. All minima and saddle states involved in the reaction channel have been characterized on the potential energy surface (PES). From PES, it is confirmed that H-abstraction from methylene (-CH2-) of ethyl (CH3CH2-) part of CH3CH2OCH2CH2Cl follows the minimum energy path. The rate constants (individual and overall) of the titled reaction are obtained using Canonical Transition State Theory (CTST) over the temperature range of 250-350K. The atmospheric lifetime and radiative efficiency of the titled molecule have also been estimated, amounting to 0.23 years and 0.024 years, respectively. The Global Warming Potentials of the 2-chloroethyl ethyl ether in 20 years, 100 years and 500 years time horizon were found to be 0.13, 0.04 and 0.01, respectively. [ABSTRACT FROM AUTHOR]

With the rapid growth of industrialization, deforestation, and burning of fossil fuels, undeniably there has been an incredible escalation of the CO 2 concentration in the atmosphere. In order to mitigate the problem, the capture and utilization of CO 2 in different value-added chemicals have thus remained topics of concerned research for more than a decade. Accordingly, we have performed molecular -level catalytic hydrogenation of CO 2 to formic acid using bare [Cu 2 ] 0,±1 dimers as catalysts. The entire investigation has been performed using a density functional theory (DFT) method employing the Perdew-Burke-Ernzerhof (PBE) functional with the def2TZVPP basis set to explore the different possible routes and efficiency of the catalysts. Results reveal the feasibility of H 2 dissociation on all three Cu 2 , Cu 2 + , and Cu 2 - dimers. The negatively charged hydride formed during H 2 dissociation on Cu 2 and Cu 2 + dimers facilitates the formation of the HCOO* intermediate over COOH*, thereby providing product selectivity for HCOOH above CO. However, the reaction on the Cu 2 - dimer forms both HCOO* and COOH* intermediates, but HCOO*, being kinetically more favorable, results in HCOOH production. The free-energy change suggests that the complete reaction on Cu 2 and Cu 2 + dimers forms a stable product compared to the Cu 2 - dimer. Furthermore, H 3 COH production is studied using the title catalysts via the obtained HCOOH* intermediate from the reaction channel. Transition state theory (TST) has been considered to evaluate the rate constants for each step of the reaction. Overall results suggest Cu 2 to be better compared to Cu 2 + and Cu 2 - dimers for HCOOH formation and Cu 2 + over Cu 2 and Cu 2 - dimers to be more efficient for H 3 COH formation. This work opens the way for further investigation of the reaction mechanism and development of an efficient catalyst for CO 2 hydrogenation.

Capture of CO 2 and its conversion into organic feedstocks are increasingly needed as society moves towards a renewable energy economy. Here, a hydride-assisted selective reduction pathway is proposed for the conversion of CO 2 to formic acid (FA) over SnO 2 monomers and dimers. Our density functional theory calculations infer a strong chemisorption of CO 2 on SnO 2 clusters forming a carbonate structure, whereas heterolytic cleavage of H 2 provides a new pathway for the selective reduction of CO 2 to formic acid at low overpotential. Among the two investigated pathways for reduction of CO 2 to HCOOH, the hydride pinning pathway is found promising with a unique selectivity for HCOOH. The negatively-charged hydride forms on the cluster during the dissociation of H 2 and facilitates the formation of a formate intermediate, which determines the selectivity for FA over the alternative CO and H 2 evolution reaction. It is confirmed that SnO 2 clusters exhibit a different catalytic behaviour from their surface equivalents, thus offering promise for future work investigating the reduction of CO 2 to FA via a hydride pinning pathway at low overpotential and CO 2 capturing., (© 2019 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.)