Energetics and kinetics of various cyano radical hydrogen abstractions.

The cyano radical (CN) is an abundant, open-shell molecule found in a variety of environments, including the atmosphere, the interstellar medium and combustion processes. In these environments, it often reacts with small, closed-shell molecules via hydrogen abstraction. Both carbon and nitrogen atoms of the cyano radical are reactive sites, however the carbon is more reactive with reaction barrier heights generally between 2-15 kcal mol lower than those of the analogous nitrogen.

Dibridged, Monobridged, Vinylidene-Like, and Linear Structures for the Alkaline Earth Dihydrides BeH, MgH, CaH, SrH, and BaH. Proposals for Observations.

This research reports a search for peculiar monobridged structures of the EH molecules (E = Be, Mg, Ca, Sr, Ba). For BeH and MgH, the monobridged geometry is not an equilibrium but rather a transition state between the vinylidene-like structure and the global minimum HE-EH linear geometry. However, for CaH, SrH, and BaH, this situation changes significantly; the linear structure is no longer the global minimum but lies higher in energy than two other equilibria, the dibridged and monobridged structures.

Convergent energies and anharmonic vibrational spectra of CaH and CaH constitutional isomers.

Three constitutional isomers of both CaH and CaH have been characterized with molecular electronic structure theory. Correlation methods as complete as CCSDT(Q) and basis sets as large as cc-pwCV5Z have been used to converge the relative energies within chemical accuracy (≤1 kcal mol). Anharmonic vibrational frequencies were computed using second-order vibrational perturbation theory employing CCSD(T)/cc-pwCVTZ cubic and quartic force-fields and a CCSD(T)/cc-pwCVQZ quadratic force field.

Mechanisms of the Ethynyl Radical Reaction with Molecular Oxygen.

The ethynyl radical, CH, is a key intermediate in the combustion of various alkynes. Once produced, the ethynyl radical will rapidly react with molecular oxygen to produce a variety of products. This research presents the first comprehensive high level theoretical study of the reaction of the CH (Σ) radical with molecular oxygen (Σ).