Donor-Stabilized Fluorido Cations and New Tungsten-Based Weakly Coordinating Anions

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The element fluorine is unique in the periodic table because it has the highest electronegativity and it is amongst the smallest in size. While it forms very stable C-F bonds, which are important in organofluorine chemistry, molecular inorganic fluorine compounds are characterized by their high reactivity. As a consequence, inorganic fluorine chemists utilize specialized synthetic methodologies, such as exclusion of moisture and maintaining samples at low temperature. Fluorine enables the synthesis of types of compounds that could not be made with other elements. Hence fluorine compounds have served as model compounds with unique reactivity profiles. Chemistry of the element fluorine has experienced a remarkable renaissance in the last decade, with spectacular discoveries and the outstanding utility of organofluorine compounds in the pharmaceutical and agrochemical industry. However, incorporation of fluorine almost always requires the use of reactive inorganic fluorinating agents. To ensure that the full range of fluorinated products is maintained and to improve safety, efficiency and selectivity, new fluorinating reagents are always needed. The current proposal focuses on inorganic fluorine chemistry and explores fundamental structural and reactivity questions, as well as potential applications of inorganic fluorides. The inorganic fluorine chemistry group in Lethbridge is one of the few groups in the world that can handle highly reactive fluorine chemicals and train students in this important field of chemistry. The proposal explores the preparation of fluorine-containing cations that are stabilized by donor molecules. Without the presence of these donor-molecules the cations would not form. The cations include main group (antimony, arsenic and sulfur) as well as transition metal (molybdenum, tungsten and rhenium) fluorides. These new cations exhibit interesting structures and reactivities that will allow their use as model compounds for high-coordinate geometries. Applications of salts of these cations will be explored as fluoride-ion acceptors, fluorination reagents and as pentafluorosulfanyl (-SF5) transfer agents. The second portion of the proposal targets new weakly coordinating anions, which are big anions where the negative charge is delocalized over a large volume. Weakly coordinating anions have already attracted vast attention in industry. This proposal targets a new class of such anions that could provide advantages to the currently used weakly coordinating anions. Applications of such anions range from lithium ion batteries to ionic liquids. Ionic liquids are important to further develop "green" chemistry since they are recyclable and do not have a vapour pressure and therefore will not cause atmospheric pollution.