Effect of an external electric field and a neighbouring atom on the torsional potential of glyoxal: A computational study

Abstract

Torsional potential of glyoxal was studied under the presence of an external electric field at the MP2/TZ2P + f level. Without an external electric field, the trans conformer is more stable than the cis conformer by 4.51 kcal/mol. The cis conformer which points two hydrogens in the field direction is stabilized when a large electric field is applied along the C2 symmetry axis, whereas the stationary point at the trans conformer disappears. The effect of a neighbouring atom was investigated by considering the complex of glyoxal with Ar and Na+. The Ar···glyoxal complex is very weakly bound. Several stationary points on the potential energy surface were located. All stationary structures corresponding to the Ar···trans-glyoxal have lower energy than those of the Ar···cis-glyoxal. The Na+···glyoxal complex has two minimum structures; the glyoxal molecule in the most stabilized complex has the cis conformation. This indicates that the interaction of glyoxal with Na+ is sufficient to change the glyoxal conformation. © 2003 Published by Elsevier Science B.V.