, respectively; Figure ). The product, formulated as [TMA]2[{(t-BuTACN-Me)Ca}2(-F)2] (9) was isolated in ca. 50% yield as a white solid, although X-ray quality single crystals could not be obtained to allow for unequivocal structure determination by X-ray crystallography (Scheme 3C). The 1 H NMR spectrum of 9, in line with the measured F chemical shift, is consistent with the presence of a 1:1 Ca:F ratio, on the basis of an equimolar ratio of the intensities of the [NMe4] + and t-BuTACN signals. We also carried out diffusion-ordered spectroscopy (DOSY) F NMR measurements on complexes 7 and 9 in THF-d8. The hydrodynamic radius estimated for complex 7 using the Stokes-Einstein equation (10.7 Å) is comparable to that of complex 9 (9.3 Å) suggesting that 9 is dimeric in the solution state, and that a monomeric species [TMA][{(t-BuTACN-Me)Ca}(F)] is unlikely. Such a species is also viewed as being unlikely on the basis of the F shift measured for 9, since terminal or close-toterminal calcium fluoride complexes have been shown to give rise to significantly higher field signals (e.g. F = -97.8 ppm for [K(NON)Ca(THF)(F)]2). As such, while other isomeric forms of complex 9 are plausible, the available data and structural precedent points to a dimeric species containing a central Ca(-F)2Ca unit. The fluoride anion delivery capabilities of the newly synthesized [{(t-BuTACN-Me)Ca}2(-F)] -systems have been evaluated under very mild conditions (room temperature, benzene solution; Scheme 4). These studies focused on cryptstabilized system [K(2.2.2-crypt)][{(t-BuTACN-Me)Ca}2(-F)] 6 because of its facile synthesis and isolation compared to 7 -9. In particular, we wished to compare the capabilities of 6 in nucleophilic fluoride delivery to recently reported NON-stabilized systems. The reaction with 1-adamantanecarbonyl chloride in C6D6 at room temperature affords 1-adamantane-carbonyl fluoride (F = 23.2 ppm) in the same yield as for [K(2.2.2crypt)][{(NON)Ca(THF)}2(-F)] (both 58%). In a similar yield, triphenylcarbenium tetrakis(pentafluorophenyl)borate ([Ph3C] [B(C6F5)4]) also reacts with 6 in C6D6 at room temperature, in this case to furnish a quaternary C-F centre (Ph3CF: F = -125.6 ppm). With a view to probing if this reactivity could be expanded to construct other fluorine-heteroatom bonds, silicon-and sulfurbased electrophiles were also trialed. Treatment of complex 6 with chlorotriphenylsilane in C6D6 at room temperature generates fluorotriphenylsilane (F = -168.9 ppm) in excellent (92%) yield after 72 h, in contrast to [K(2.2.2-crypt)][{(NON)Ca(THF)}2(-F)], which plateaus at a more moderate yield (62%) after ~15 min. Finally, we exposed complex 6 to tosyl chloride in C6D6 at room temperature, generating tosyl fluoride (F = 66.6 ppm) in good/excellent yield after 30 min/72 h (68%/93%). The corresponding reaction with [K(2.2.2-crypt)][{(NON)Ca(THF)}2(-F)] gives only 17% conversion to tosyl fluoride after 15 min, and does not improve with longer reaction times. It is worth noting that even the most effective NON-derived system ([(NON)Ca(THF)(-F)K(18-crown-6)]) affords only a 35% yield of the S-F bonded product under comparable conditions (benzene, room temperature, 24 h).