Tetra-n-butylammonium μ-fluorido-bis-{tris[2,2,2-trifluoro-1,1-bis(trifluoromethyl)ethanolato-κO]aluminate(III)}

The metathesis reaction of Ag[(RO)(3)Al-F-Al(OR)(3)] and n-BU4NBr in CH2CI2 yields nearly quantitatively n-BU4N+center dot-[(RO)(3)Al-F-Al(OR)(3)](-) [with R = C(CF3)(3))] or (C16H36N)-[Al-2(C4F9O)(6)F]. In the asymmetric unit, two entire cations and four half-anions (one is disordered over two positions) are found. The intramolecular distances are comparable to those found in other n-BU4N+ or [(RO)(3)Al-F-Al(OR)(3)](-`) salts. Only weak interactions outside the sum of the van der Waals radii [r(F + H) = 2.6 angstrom] are found between the cations and anions. The title compound is considerably soluble in CH2CI2, which makes this salt a possible candidate as supporting electrolyte for electrochemical applications in nonpolar solvents. In addition, the [(RO)(3)Al-F-Al(OR)(3)](-) anion is very stable against oxidation. Two CF3 groups of one anion are disordered over two positions; the site occupancy ratios are 0.64:0.36 and 0.78:0.22.