Ionization and protonation of NaC 3: a theoretical study

Abstract

A theoretical study of the NaC 3 + and NaC 3H + systems has been carried out. Predictions have been made for some of the molecular properties, which could help in their possible experimental detection. The predicted global minimum for NaC 3 + is the linear isomer 1s ( 1Σ). The lowest-lying triplet state is a three-membered ring 3t ( 3B 2), lying about 27.1 kcal/mol higher in energy than the predicted global minimum at the G2(P) level. In the case of NaC 3H +, there are two isomers that lie close in energy: a linear species, 1d ( 2Π), and a three-membered ring, 4d ( 2A′). The most reliable levels of theory employed predict that 1d ( 2Π) is the global minimum, whereas 4d ( 2A′) is predicted to lie 5.3 kcal/mol higher in energy at the G2(P) level. In any case it seems that both structures could be accessible to experimental detection. Low ionization potential and high proton affinities are obtained for the most stable NaC 3 isomers. Therefore, if present in the interstellar medium, NaC 3 should be easily ionized and would react quite easily to give the protonated species.