Psh. Wong et al., ION MOLECULE REACTIONS OF TITANIUM AND TITANIUM DICHLORIDE CATIONS WITH PYRIDINE - ACTIVATION OF THE PYRIDINE RING IN THE GAS-PHASE/, Rapid communications in mass spectrometry, 10(8), 1996, pp. 927-931
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.