ION MOLECULE REACTIONS OF TITANIUM AND TITANIUM DICHLORIDE CATIONS WITH PYRIDINE - ACTIVATION OF THE PYRIDINE RING IN THE GAS-PHASE/

Mass-selected Ti+ or TiCl2+ ions can be used to activate pyridine mole cules, This unusual chemical activation is evident from reaction produ ct tandem (MS/MS or MS(2)) spectra recorded at nominal zero collision energy which display abundant ions due to dehydrogenation and HCN loss from the ion/molecule complexes, The Ti+ cluster ions, (PyTi+, n = 2- 5, undergo ring cleavage with the loss of neutral HCN while the adduct ion PyTi(+) undergoes ring cleavage with the loss of HCN and C2H2. By contrast, the cluster ions, (Py)(n)TiCl2+, n = 2-4, simply undergo th e loss of a pyridine ligand under mild collision conditions while the mono-adduct PyTiCl(2)(+), undergoes sequential loss of a molecule of H Cl and HCN forming C5H4NTiCl+ and C4H3TiCl+ respectively, These experi ments show that Ti+ and TiCl2+ are highly reactive, activating the pyr idine ring and facilitating ring cleavage. Mechanisms which yield cycl obutadienyl derivatives are proposed for these ring activation reactio ns and are supported by MS(3) experiments.