Ion/Molecule Reactions of Titanium and Titanium Dichloride Cations with Pyridine: Activation of the Pyridine Ring in the Gas Phase

✍ Scribed by Philip S. H. Wong; Shuguang Ma; R. Graham Cooks

• Publisher: John Wiley and Sons
• Year: 1996
• Tongue: English
• Weight: 440 KB
• Volume: 10
• Category: Article
• ISSN: 0951-4198
• DOI: 10.1002/(sici)1097-0231(19960610)10:8<927::aid-rcm531>3.0.co;2-0

✦ Synopsis

Mass

-selected Ti+ or TiCl; ions can be used to activate pyridine molecules. This unusual chemical activation is evident from reaction product tandem (MS/MS or MS? spectra recorded at nominal zero collision energy which display abundant ions due to dehydrogenation and HCN loss from the ionholecule complexes. The Ti+ cluster ions, (Py),Ti+, n=2-5, undergo ring cleavage with the loss of neutral HCN while the adduct ion @Ti+ undergoes ring cleavage with the loss of HCN and C&. By contrast, the cluster ions, (Py),TiCI;, n=2-4, simply undergo the loss of a pyridine ligand under mild collision conditions while the mono-adduct PyTiCl;, undergoes sequential loss of a molecule of HCI and HCN forming C,&NTiCl+ and C,H3TiCl+ respectively. These experiments show that Ti+ and TiCl; are highly reactive, activating the pyridine ring and facilitating ring cleavage. Mechanisms which yield cyclobutadienyl derivatives are proposed for these ring activation reactions and are supported by MS3 experiments.