Methane Dehydrogenation by Niobium Ions: A First-Principles Study of the Gas-Phase Catalytic Reactions

Abstract

The issue of reactivity differences of the ions Nb+ and Nb2+ toward methane (CH4 + Nb+ → NbCH2 + + H2 and CH4 + Nb2+ → NbCH2 2+ + H2) is addressed using CCSD(T)//MP2 and CCSD(T)//B3LYP calculations. A thorough description of the reaction mechanisms and analyses of the geometrical structures, chemical bonds, and molecular orbitals provide important insights into the chemistry of the niobium species. The overall results indicate highly labile kinetics and more favorable thermochemical conditions for Nb2+. The NBO, AIM, and FERMO analyses provide a better understanding of the reactivity differences in the niobium reactions.

Gas‐phase water activation by Th atom: Reaction mechanisms and topological analysis

“…Bond orders analysis for all of the minima and transition states (lowest‐energy spin state species) involved in the reaction of Th with H 2 O are listed in Table . The AIM method has proven to be a very helpful tool for analyzing the evolution of chemical bonds, in particular for the analysis of the chemical problems involving bond‐breaking and ‐forming reactions . ▿ 2 ρ (BCP) indicates the regions where ρ (BCP) is depleted or concentrated.…”

“…▿ 2 ρ (BCP) indicates the regions where ρ (BCP) is depleted or concentrated. For shared bonds, ▿ 2 ρ (BCP) is negative, while positive values are observed for interactions showing closed‐shell character, and the positive ▿ 2 ρ (BCP) indicate an ionic nature of the chemical bonds …”

Water OH Bond Activation by Gas‐Phase Plutonium Atoms: Reaction Mechanisms and Ab Initio Molecular Dynamics Study

“…Mayer bond order analyses for all of the minima and transition states (lowest-energy spin state species) involved in the reaction of Pu + H 2 O are listed in Table 4. [34,54,55] The topological properties of the (3,-1) bcp were obtained in terms of the electron density CHEMPHYSCHEM ARTICLES www.chemphyschem.org 1(r) (where r represents the position of the bcp), its Laplacian r 2 1(r) at the critical bond, the total electron energy density H(r), the potential energy density V(r), and the kinetic electron energy density G(r). [34,54,55] The topological properties of the (3,-1) bcp were obtained in terms of the electron density CHEMPHYSCHEM ARTICLES www.chemphyschem.org 1(r) (where r represents the position of the bcp), its Laplacian r 2 1(r) at the critical bond, the total electron energy density H(r), the potential energy density V(r), and the kinetic electron energy density G(r).…”

“…However, this criterion has been proven to be insufficient in describing the nature of bond, [55,57] because the r 2 1(bcp) of polar covalent bonds can also be positive. However, this criterion has been proven to be insufficient in describing the nature of bond, [55,57] because the r 2 1(bcp) of polar covalent bonds can also be positive.…”

“…However, this criterion has been proven to be insufficient in describing the nature of bond, [55,57] because the r 2 1(bcp) of polar covalent bonds can also be positive. [55,60] As shown in Figure 3, the topological description of the first complex Pu-OH 2 showed an absence of a disynaptic valence basin between plutonium and oxygen atoms. The H(r) criterion was proven to be adequate for the characterization of the nature of a bond for heavy-atom systems.…”