GAS-PHASE STABILITY AND STRUCTURE OF THE CLUSTER IONS CF3-2)(N), CF3+(CF4)(N), AND CF4H+(CF4)(N)((CO)(N), CF3+(N)

Gas-phase thermochemical stabilities and structures of cluster ions CF 3+(CO)(n), CF3+(N-2)(n), CF3+(CF4)(n), and CF4H+(CF4)(n) have been stu died with a high-pressure mass spectrometer and ab initio calculations . The clusters examined are found to have the shell structures CF3+(CO )(1)(CO)(3)(CO)(3)(CO)(n-7), CF3+(N-2)(2)(N-2)(3)(N-2)(n-5), CF3+(CF4) (2)(CF4)(n-2), and CF4H+(CF4)(1)(CF4)(n-1). The CF3+ ion is bound with CO to form the core CF3CO+ in the cluster, while the interaction betw een CF3+ and N-2 or between CF3+ and CF4 is mainly electrostatic. The unusually small bond energy for the symmetric proton-bound dimer CF4H... CF4 (5.1 kcal/mol) is observed, which indicates that CF4H+ and CF4 are very poor electrophile and nucleophile, respectively.