Journal of Physical Chemistry, Vol.100, No.42, 16817-16821, 1996
Collision-Induced Dissociation of Vanadium-Carbon Cluster Cations
Collision-induced dissociation (CID) studies of vanadium-carbon clusters were made employing a triple quadrupole mass spectrometer system coupled with a laser vaporization source. The results reveal that the primary dissociation channel is loss of a metal atom for all but V8C14+, which loses C-3, and V9C14+ which loses both V and VC2. These findings are in general agreement with earlier ones reported for the titanium system, except that under single-collision conditions V8C14+ loses a C-3 unit to become V8C11+, while Ti8C14+ loses Ti. Importantly, we show that both the met-car V8C12+ and V8C13+ are significantly more resistant to dissociation than the neighboring V8C11+ cluster species. In addition to reporting the primary fragmentation products of several VxCy+ clusters, we also present the results of studies of the multiple-collision dissociation patterns of both V8C12+ and V8C13+, which are observed to undergo C-2 and C-3 loss after some metal loss has occurred. These findings are consistent with the building patterns observed for these clusters and our proposed structure for V8C12+. Through study of the dissociation of V9C12+, the ionization energy of V8C12 is found to be less than that of the vanadium atom, i.e., less than 6.74 eV, in accord with theoretical predictions.
Keywords:BINARY METAL METALLOCARBOHEDRENES;ELECTRONIC-PROPERTIES;GEOMETRIC STRUCTURE;M8C12 CLUSTERS;BOND-ENERGIES;GAS-PHASE;TI8C12;STABILITY;CARS;TITANIUM