Properties of CH bonds in inorganic and isopropyl esters
The work described in this thesis sets out the results of a vibrational study on a series of methyl and isopropyl sulfate, selenate and phosphate esters, based on a detailed analysis of the infrared spectra of an extended series of deuterated and partially deuterated isotopomers of the compounds of interest. Due to difficulties intrinsic to the analytical method it was important to develop a synthetic method that would be equally applicable to all the inorganic esters studied. The use of a transmetalation reaction, followed by addition of the required isotopically substituted alkyl halide allowed all isotopomers to be easily produced and analysed. A detailed analysis of the infrared spectra was carried out for all isotopomers prepared with particular emphasis on the vibrations associated with the alkyl groups. This allowed, where possible, the accurate assignment of peaks to fundamental, overtone or combination modes. Using the information gained along with well-established relationships between CH bond properties and the experimentally observed isolated CH stretching frequency, visCH, it was possible to calculate CH bond lengths, bond dissociation energies and where applicable HCH bond angles. The use of visCD instead of visCD as an alternative predictor of CH bond properties was also investigated. The results showed clearly that bond properties derived from visCD data are subject to a much greater degree of uncertainty than those obtained from visCH.