Abstract
Calcium fluoride is the ultimate source of all fluorochemicals. Current synthetic approaches rely on the use of HF, generated from naturally occurring fluorspar and sulfuric acid. Methods for constructing E-F bonds directly from CaF(2) have long been frustrated by its high lattice energy, low solubility and impaired fluoride ion nucleophilicity. Little fundamental understanding of the reactivity of Ca-F moieties is available to guide methodology development; well-defined molecular species containing Ca-F bonds are extremely rare, and existing examples are strongly aggregated and evidence no nucleophilic fluoride delivery. Here, by contrast, we show that by targeting anionic systems of the type [L(n)(X)(2)CaF](-), monomeric calcium fluoride complexes containing single Ca-F bonds can be synthesized, including via routes involving fluoride abstraction from existing C-F bonds. Comparative structural and spectroscopic studies of mono- and dinuclear systems allow us to define structure-activity relationships for E-F bond formation from molecular calcium fluorides.