Different mass spectrometers, widely differing purposes : from structure elucidation tool to gas phase ion-molecule reactions.

Abstract

This thesis is comprised of two parts with all the work carried out centred around the use of two mass spectrometers with vastly differing capabilities and with the experimental results obtained supported or refuted with the aid of theoretical quantum chemical calculations. For the last two decades our research group has been interested in cumulenes and hetero-cumulenes, some detected and some not as yet in their interstellar environs. The work discussed in the first part of this thesis is a continuation of some of that work and a comparison with the new work undertaken within. Our interest is predominantly orientated towards the neutral systems and their rearrangements. Our work on interstellar molecules is of interest because some of the systems investigated here and in the past, along with their precursor molecules are already known interstellar molecules and some have been implicated as possible precursors for the building blocks of life and some as possible antibiotics. The first part of this thesis uses a combination of mass spectrometric techniques using a VG ZAB 2HF mass spectrometer (mainly charge reversal mass spectrometry) and/or theoretical quantum calculations to investigate the structures and energetics of the neutral tetra-atomic and hetero-cumulenic systems CCCN, CCCSi, CCCP, H₂CCCN, and ONCS (a possible primordial antibiotic). The second part of this thesis involves the modification of a Finnigan LCQ ion trap mass spectrometer in order to perform gas phase ion-molecule reactions between selectively generated carbanions and carbon disulfide. The investigation carried out in the second part of this thesis is a revisit on our earlier group research on the gas phase ipso (Smiles) rearrangement. It was proposed that the adducts formed between the carbanions and CS₂ undergo Smiles type rearrangements via ipso intermediates upon collision induced dissociation CID.