Thermochemical stabilities of the gas-phase cluster ions H 3C +(N 2) n

Abstract

Gas-phase equilibria for clustering reactions of CH 3 + with N 2 were measured with a pulsed electron-beam high-pressure mass spectrometer. The bond energies were found to show irregular decreases for H 3C +(N 2) n with n=1, 4, and 6. Due to the formation of the covalent bond with n=1, the positive charge is dispersed in the H 3CN 2 + complex which is solvated preferentially by three more N 2 ligands. The ab initio calculations revealed that the cluster ion with n=4 has the three-fold shell structure, H 3CN 2 +(N 2) 3, with the C 3v symmetry. The most stable cluster ion with n=6 has the four-fold shell structure (N 2) 1H 3CN 2 +(N 2) 4. The attachment of n=7 and 8 N 2 ligands results in the relaxation of the four-fold structure of the cluster with n=6 to the three-fold one with n=8, (N 2) 1H 3CN 2 +(N 2) 3(N 2) 3, due to the steric congestion.