A THEORETICAL-STUDY ON THE STRUCTURE, INTERNAL-ROTATION AND HEAT OF FORMATION OF THE PROTONATED FLUOROFORM CATION (CF3H2+)

Ab initio calculations have been performed to examine the properties o f the protonated fluoroform cation (CF3H2+). These calculations show t hat the global minimum for CF3H2+ is [CF2H ... FH](+) among three poss ible configurational isomers. This isomer is suggested to be an ion-di pole complex between CF2H+ and FH. The barrier to internal rotation of the bond between carbon of CF2H+ and fluorine of HF is calculated as 0.96 kcal mol(-1) at the MP2/6-31G(d,p) level of theory. The heat of f ormation of CF3H2+ at 298.15 K is estimated to be 60.6 kcal mol(-1) fr om the G2 calculation. (C) 1998 Elsevier Science B.V.