Vibrational spectroscopy and dynamics of ionic complexes of CH5+, CH5+(A)(x)(B)(y) (A,B=Ar,N-2,CH4; x,y=0-5)

The vibrational spectra for the ionic complexes of CH5+, CH5+(A)(x)(B)(y) (A, B=Ar, N-2, CH4; x, y=0-5) in the 2500-3200 cm(-1) frequency region are presented. The scrambling motions of the CH5+ core slow considerably as the ion-molecule interactions increase (Ar <N-2 <CH4), and as the number of the neutral molecules in the complexes increase. The CH5+ core of CH5+(CH4)(n) (eta greater than or equal to 3) was regarded as rigid. For CH5+(N-2) and CH5+(CH4)(n) (n=1, 2, 3), the H-H stretching bands of the CH5+ core, which are direct evidence for three-center two-electron bonding in CH5+, were found in the 2500-2700 cm(-1) region. The structures of the methane-coordinated carbonium ions CH5+(CH4)(n) (n=1-5) were predicted from the analysis of the vibrational spectra, improving on the previous theoretical and experimental predictions.