Gas phase reactions of the metallocarbohedrenes Ti8C12+, Nb8C12+, and Ti7NbC12+ With two different types of molecules, namely, acetone and methyl iodide, are investigated at near thermal energy by employing a laser-induced plasma source coupled with a triple quadrupole mass spectrometer. Two general types of reactions are observed: molecular associations and atom abstraction reactions. in agreement with earlier studies on the interaction of Ti8C12+ With polar molecules, association reactions are found to dominate in the case of acetone. But, the incorporation of even one Nh greatly affects the reactivity. For example, the extraction of one and two oxygen atoms from acetone is also observed for Nb8C12+ and Ti7NbC12+; these products are found to sequentially associate with acetone to form Nb8C12+(O)(1-2)(acetone)(n) and Ti7NbC12+(O)(1-2)(acetone)(n). The reaction involves breaking C=O bonds and forming M-O bonds, evidently due to the presence of the dipole-induced charge center of Nb8C12+ and Ti7NbC12+ Possible reaction mechanisms are proposed which take into account the electronic structures of Nb8C12+, Ti7NbC12+, and Ti8C12+ In reactions with methyl iodide, all three metallocarbohedrenes display similar mechanisms, namely, abstraction of iodine atoms. But, there is a gnat enhancement in the number upon the substitution of one or more titaniums by niobium atoms. The bonding strength of Ti8C12+-I is determined to be larger than 56 kcal/mol. Considering the cagelike structure of metallocarbohedrenes, these results provide further insight into the relationship between their reactivities and electronic structures.
