Studies of solvation by spectroscopic methods.

The work described in this thesis is concerned with the use of relatively simple compounds in dilute solution to study solvation phenonena. Spectroscopic techniques such as infrared and NMR have been used to follow the environment of the 'probe' throughout various mixed and pure solvent states. The potential of NMR spectroscopy to solvation has been explored. Solvent effects on the resonance show that the sensitivity decreases in the order phosphine oxides - phosphonates - phosphates. This trend is also seen amongst carbonyl ccmpounds where the NMR sensitivity decreases in the order ketones - acetates - carbonates. It is thought that the paramagnetic contribution to the chenical shift may be inportant in dictating these shifts. Based on the evidence of previous work, it was always accepted that water formed the hydrate with maximum solvation number. The results from the ester study are important since it may be a mistake to assume such fixed solvation. The fundamental infrared work incorporates a study that investigates the relevance of coupling in systems such as phosphate mono-anions, carboxylate anions and others. The results for the phosphate mono-anions shew that the coupling between the P-O modes is sensitive to solvent perturbations. This trend is also partly seen amongst the carboxylate anions. Finally, the validity of Gutmann's Acceptor Number is examined. It is concluded that this solvent scale is only applicable to solvated states that are identical with those for triethylphosphine oxide.