GENERATION OF THE THERMODYNAMICALLY STABLE DICATIONS ALF2-STRIPPING MASS-SPECTROMETRY( AND SIF2+ VIA CHARGE)

The theoretically predicted (Kolbuszewski; M.; Wright, J. S. J. Phys. Chem. 1995, 99, 3455) existence of the thermodynamically stable dicati ons AlF2+ and SiF2+ is demonstrated by charge-stripping mass spectrome try. The vertical second ionization energies (MF(+) --> MF(2+) + e, M = Al, Si) of these species have been determined as 19.7 +/- 1.5 eV (Al F+) and 21.7 +/- 0.6 eV (SiF+) and agree favorably with theoretically calculated values using both single-reference and multireference appro aches. Evidence for the formation of the first excited triplet state o f SiF+ ((3) Pi) upon electron ionization of silicon tetrafluoride is p resented.