Accurate rate constants for elementary reactions of molecular hydrogen and carbon monoxide mixtures and the role of the H rich environment.

This investigation provides accurate rate constant values for a set of elementary reactions relevant to mixtures between molecular hydrogen (H) and carbon monoxide (CO) such as syngas. We considered intermediates and products including formaldehyde (HCO), hydroxymethylene (c-HCOH and t-HCOH) and methanol (CHOH). The calculations were performed employing the improved canonical variational transition state theory with small-curvature tunneling corrections based on high-level electronic structure results.

The relativistic effects on the methane activation by gold(I) cations.

The reactivity of gold has been investigated for a long time. Here, we performed an in-depth analysis of relativistic effects over the chemical kinetic properties of elementary reactions associated with methane activation by gold(I) cations, CH + Au ↔ AuCH + H. The global reaction is modeled as a two-step process, CH + Au ↔ HAuCH ↔ AuCH + H.

Tunneling Enhancement of the Gas-Phase CH + CO Reaction at Low Temperature.

The rates of numerous activated reactions between neutral species increase at low temperatures through quantum mechanical tunneling of light hydrogen atoms. Although tunneling processes involving molecules or heavy atoms are well known in the condensed phase, analogous gas-phase processes have never been demonstrated experimentally. Here, we studied the activated CH + CO → HCO + CO reaction in a supersonic flow reactor, measuring rate constants that increase rapidly below 100 K.

Accurate Rate Constants for the Forward and Reverse H + CO ↔ HCO Reactions at the High-Pressure Limit.

The forward and reverse H + CO ↔ HCO reactions are important for combustion chemistry and have been studied from a wide variety of theoretical and experimental techniques. However, most of the chemical kinetic investigations concerning these processes are focused on low pressures or fall-off regions. Hence, a high-level electronic structure treatment was employed here in order to provide accurate rate constant values for these reactions at the high-pressure limit along temperatures from 50 to 4000 K.

A Proposal for the Mechanism of the CH + CO Reaction.

Few experimental studies on the CH + CO global reaction propose H, CO, and HCO as major products. However, the reaction mechanisms behind this process have not yet been elucidated. Moreover, some intriguing kinetic particularities were noticed in these previous investigations.

The infrared fundamental intensities of some cyanopolyynes.

Some cyanopolyynes, HC(n)N (n=1, 3, …, 17), are investigated by means of calculations at the MP2/cc-pVTZ and CCSD/cc-pVDZ levels. Although the MP2/cc-pVTZ results for geometries and molecular dipole moments are encouraging, the CCSD/cc-pVDZ level was superior for the study of infrared fundamental intensities. The main bands are also analyzed with a charge-charge flux-dipole flux (CCFDF) partition model based on quantities given by the Quantum Theory of Atoms in Molecules (QTAIM).