The Molecular Structures and Energetics of Cl₂CO, ClCO, Br₂CO, and BrCO

Abstract

The heats of formation of ClCO, Cl 2 CO, BrCO, and Br 2 CO have been calculated at high levels of ab initio molecular orbital theory. Geometries and frequencies for the two closed shell molecules were calculated at the MP2 level. The geometries of the two radicals were calculated at the level of coupled cluster theory with single and double excitations including a perturbative treatment of the connected triple excitations (CCSD-(T)) with the augmented correlation consistent triple-basis set (aug-cc-pVTZ). Extrapolation of the total energies (aug-double, aug-triple, aug-quadruple) to the complete 1-particle basis set limit was performed to further reduce the basis set truncation error. Additional improvements in the atomization energy were achieved by applying corrections for core/valence correlation, scalar relativistic effects, and spin-orbit coupling. 1.5 (calc). The radical BrCO is predicted to be only weakly bound with a long quasi-linear Br-C bond length of 3.09 Å, and a Br-CO binding energy (∆E elec ) of only 1.6 kcal/mol calculated at the CCSD(T) estimated basis set limit. Inclusion of both molecular and atomic spin-orbit coupling effects reduces this to just 0.3 kcal/mol.

Anion Photoelectron Spectra and Ab Initio Calculations of the Iodide–Carbon Monoxide Clusters: I–···(CO)n, n = 1–4

“…The van der Waals style complexes have been predicted previously by our group, and others, − for the chlorine and bromine–carbon monoxide analogues. In the case of the chlorine–carbon monoxide complex, a third minimum with a closer interaction between the chlorine and CO was located, the “covalently bound” ClCO radical.…”

“…The ClCO radical complex, in particular, has been proposed as an intermediate in the production of phosgene from Cl 2 and CO, has a role in the reaction pathways of CO in our atmosphere, and is also postulated as an important intermediate in the chemistry of the Venutian atmosphere . The BrCO and ClCO species have received prior experimental and theoretical attention, via matrix and gas phase spectroscopy, − kinetic studies, ,− and via ab initio calculations. − …”

Systematically Convergent Correlation Consistent Basis Sets for Molecular Core−Valence Correlation Effects: The Third-Row Atoms Gallium through Krypton

“…59,60,[65][66][67][68] It is the goal of this investigation to provide new core-valence correlation consistent basis sets to complete the full "suite" of basis sets for the elements Ga-Kr. The effects of core-valence correlation on the bond lengths, vibrational frequencies, and dissociation energies of the homonuclear dimers of these six elements will also be examined.…”

Kinetics of the Reactions of the CHBr2and CHBr2O2Radicals with O2and NO

“…However, they also observed formation of small amounts of CO, only some of which could be attributed to the thermal decomposition of the product CHBrO. They suggested that as much as 5% of the CHBr 2 O could be decomposing according to the reaction followed by Reaction 5 is expected to be very fast, since the Br−CO bond is thought to be very weak . Consequently the present experiments, which measure only Br atoms, would still record a Yield of unity.…”