We wanted to pursue a complimentary strategy for the synthesis of well-defined Ca-F complexes based on O-donor ligand scaffolds, and to investigate their capabilities for fluoride anion delivery. In contrast to the diamido NON ligand, which typically adopts a meridional geometry when tridentate, we focused on ligand design which would offer anionic O-ligation, targeting enhanced binding of oxophilic calcium and thus reducing side reactions that involve the ligand as a competing target for electrophilic substrates. Additionally, a greater degree of ligand three-dimensionality and increased denticity were targeted in order to saturate the Ca 2+ centre, and reduce the extent of aggregation. With this in mind, we were attracted to macrocyclic ligand scaffolds, notably 1,4,7-triaza-cyclononane (TACN) derived ligands. Such donors have been shown to encapsulate metal cations such as Al 3+ and Ga 3+ , and allow for fluorination and onward applications which extend to F imaging. Other closely related macrocyclic ligands such as crowns, azacrowns, or DOTA (CH2CH2NCH2CO2H)4 are less suitable for the intended application since they do not provide adequate X-type coordination modes even though they have been shown to encapsulate Ca 2+ cations. To our knowledge there is only one structurally characterized (TACN)Ca complex, and none containing a Ca-F bond. Herein, we report on synthetic approaches for the generation of anionic (TACN)Ca fluoride complexes and on the fluoride delivery chemistry thereof.