Organofluorine compounds are highly desirable products owing to the unique physical and chemical properties imparted by fluorine. Fluorocarbons are useful molecules that are used in multiple industries such as refrigeration, agrochemicals, pharmaceuticals, insecticides, high-value fluoropolymers and reagents in catalysis. As ligands, they are privileged in the relative inertness of the C–F bonds and their electrophilicity, which makes them ideal candidates for coordination chemistry with late, electron rich metals. Chapter 2 describes the preparation of new Ni metallacyclopentene complexes with phosphite and bis(phosphine) ligands and investigates the reaction of the latter with Lewis acidic trimethylsilyltriflate, TMSOTf (Tf = SO2CF3). As phosphine ligands react with the perfluoro-butadiene (PFB) substrate, the phosphite complex Ni((2-C4F6)[P(O-i-Pr)3]2 (2-1) was prepared from Ni(cod)2 /2 P(O-i-Pr)3 and excess PFB. Reaction of 2.1 with bis(phosphine) dppe [1,2-bis(diphenylphosphine)ethane] proceeded slowly with release of P(O-i-Pr)3 and formation of electron-rich Ni(2-C4F6)(dppe) (2-2) that undergoes fluoride abstraction using TMSOTf. The major product is proposed to be a dienyl complex resulting from ring contraction and cycloreversion. In Chapter 3 we investigate reactions of fluoroalkenes with cobalt hydrides containing phosphine and phosphite ligands in order to see if their reactivity can be controlled by the ligands’ steric and electronic properties. The four cobalt compounds used were CoH[P(OiPr)3]4 (3-1), CoH[P(O-o-tol)3]n (3-2), CoH(triphos)(CO) (3-3); [triphos = bis(diphenylphosphinoethyl)-phenylphosphine], and CoH(PPh3)3(N2) (3-4). In light of previous reports of tetrafluoroethylene insertion into Co carbonyl hydrides, we were surprised that analogous reactivity was not observed except for 3-4. Instead, reactions with hexafluoropropene gave a mixture of alkene cobalt fluoride and cobalt alkenyl complexes. In Chapter 4 we summarize our contributions to knowledge and compare our results to those from the current state of the art.

No description available.

The following work describes the synthesis of compounds carrying a vicinal difluoro motif and the evaluation of this structural element to influence the conformation of organic molecules. The synthesis of erythro and threo 1,2-difluoro-1,2-diphenylethane was achieved by bromofluorination and subsequent halogen exchange from stilbene. Oxidative degradation of the phenyl rings allowed to access erythro and threo 2,3- difluorosuccinic acids and a variety of derivatives thereof. The conformations of these compounds were investigated by means of X-ray analysis and NMR spectroscopy. Conformational analysis of derivatives of 2,3-difluorosuccinic acid was carried out using JHFandJHHNMR coupling constants. A clear preference for the conformations in which the two vicinal C-F bonds are gauche emerged from these calculations, which was confirmed by temperature and solvent dependent NMR analyses. The vicinal difluoro motif was incorporated into small peptide structures. In the solid state, a strong preference to align the vicinal C-F bonds gauche to each other was observed and when adjacent to an amide moiety, the C-F bond was found to prefer an anti periplanar orientation with respect to the carbonyl bond. These effects appeared to override steric and electrostatic interactions. The conformation of these fluorinecontaining peptides showed a clear dependence on the stereochemicaol rientation of the C-F bonds, and this appears to be an effective tool for influencing the secondary and consequently tertiary structure in a predictable manner. In order to access single enantiomerso f peptides having the vicinal difluoro, motif, a stereoselectiver oute to R,R and SS 2,3-difluorosuccinic was developed. This involved nucleophilic fluorination of the cyclic sulfates generated from (R, R)- and (SS)- diethyl tartrates and subsequent deoxofluorination of the intermediate fluorohydrins.

Thesis (M.S.)--Oregon State University, 2008. / Printout. Includes bibliographical references (leaves 56-58). Also available on the World Wide Web.

Thesis (Ph. D.)--Rutgers University, 2010. / "Graduate Program in Chemistry." Includes bibliographical references.

Thesis (Ph.D.) - University of St Andrews, May 2009.

published_or_final_version / Chemistry / Master / Master of Science

No description available.

Photocopy of typescript. / Digitized by Kansas Correctional Industries

Thesis (M. Sc.)--University of Hong Kong, 1966. / Typewritten.