Acta Cryst. (2007). E63, m2144  [ doi:10.1107/S1600536807033533 ]

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

I. Krossing and I. Raabe

Abstract: The metathesis reaction of Ag[(RO)₃Al-F-Al(OR)₃] and n-Bu₄NBr in CH₂Cl₂ yields nearly quantitatively n-Bu₄N⁺.[(RO)₃Al-F-Al(OR)₃]^- [with R = C(CF₃)₃)] or (C₁₆H₃₆N)[Al₂(C₄F₉O)₆F]. 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)₃Al-F-Al(OR)₃]^- salts. Only weak interactions outside the sum of the van der Waals radii [r(F + H) = 2.6 Å] are found between the cations and anions. The title compound is considerably soluble in CH₂Cl₂, which makes this salt a possible candidate as supporting electrolyte for electrochemical applications in nonpolar solvents. In addition, the [(RO)₃Al-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.

Online 18 July 2007

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