Gas Phase Study of the Clustering Reactions of C2H5+, s-C3H7+, and t-C4H9+ with CO2 and N2O: Isomeric Structure of C2H5+, C2H5+(CO2)n, and C2H5+(N2O)n

Abstract

The thermochemical stabilities of gas phase cluster ions C 2 H 5 +(Sol) n , s-C 3 H 7 +(Sol) n , and t-C 4 H 9 +(Sol) n (Sol = CO 2 and N 2 O) were determined using a pulsed electron beam high-pressure mass spectrometer. The stabilities and structures of those cluster ions were studied theoretically by density functional theory calculations. For the free C 2 H 5 + ion, not the classical but the nonclassical bridged form is likely to be the major component. B3LYP/6-311+G(2d,p) calculations showed that the classical structure is absent. In the clustering reaction of C 2 H 5 + with Sol, a hydrogen bond type loose complex of the nonclassical C 2 H 5 + with Sol is initially formed, which is followed by the intramolecular isomerization of C 2 H 5 + to the classical structure forming the stronger bond with Sol. Surprisingly small bond energies of 4-5 kcal/mol for s-C 3 H 7 +Sol and t-C 4 H 9 +Sol arise from the hyperconjugation effect of methyl groups.