Ab initio and DFT study of carbon monoxide cyclic oligomers, (CO)2 to (CO)6

Abstract

Structural, thermochemical stability, electrical and molecular orbital properties of (CO)n cyclic oligomers of CO (oxocarbons) have been calculated using RHF and DFT-B3LYP levels of theory with 6-31G*basis set. Contributions of these compounds in the macroscopic properties of solid CO have been investigated. Atoms in molecule (AIM) and NBO analyses have been carried out to study in detail the nature of the C-C bonds in these molecules. Population analysis has been used to search for any possible aromaticity in the rings of these cyclic oxocarbons. AIM and population analysis showed that ring bonds in the (CO)3 molecule have an aromatic character significantly more than those in other molecules do. The results of this study showed that (CO)n cyclic oligomers do not contribute significantly to the physicochemical properties of CO in the solid phase due to being thermodynamically instable at standard pressure and temperature. © 2003 Elsevier Science B.V. All rights reserved.