Experimental and computational studies of unusual P-donor ligands and their coordination chemistry

This thesis is concerned with the use of fluorophosphite ligands in rhodium-catalysed hydroformylation. Work has been carried out to synthesise two novel fluorophosphites, L6 and L7 (shown in Figure 1), via a new synthetic method, and computational work has been executed to map the free energy surfaces of the species in the hydroformylation cycle with two known fluorophosphites. This work aims to enhance the understanding of fluorophosphites in terms of their electronic and steric effects upon changing the backbone with the goal to put these fluorophosphites to the test in a catalytic run in the laboratory. The new cyclic fluorophosphites formed contained 6-membered dioxaphosphacycles and were derived from naphthalene-1,8-diol. Upon protection of the alcohol groups, lithiation reactions with n-BuLi were used for substitution at the ortho position with phenyl groups by Suzuki coupling of phenylboronic acid. Following deprotection, the fluorophosphite group was incorporated into the molecule by reaction with PCl3 and then SbF3. The resulting 31P and 13F NMR spectra of compounds L2, L6 and L7 revealed the peaks to lie close to each other, representing the similarity of the electronic properties of the compounds despite the change in steric effects. The computational work focused on modelling the catalytic cycle of a rhodium-catalysed hydroformylation reaction using fluorophosphite ligands. P(OMe)2F, L5, was chosen as a simple fluorophosphite ligand to help gain an insight into the general trends in free energy observed in a hydroformylation cycle. Then, a model fluorophosphite L2 (Fig. 1) was used to observe the differences in the trends when a dioxaphosphacyclic ligand was used. The key reflections were that the free energy barriers were closer in energy in comparison to the simpler ligand, showing that phosphite ligand exchange with CO is more likely to occur for L2. Lastly, 52 fluorophosphites were added to the Ligand Knowledge Base (