Tetrabutylammonium salt of the B 24 F 22 4− anion. Two B 12 F 11 2− icosahedra linked by a 2c–2e BB bond and surrounded by a sheath of CH· · ·FB hydrogen bonds

Abstract The B 24 F 22 4− anion, which was formed as a minor by‐product when the B 12 H 12 2− anion was treated with F 2 in liquid HF, has been isolated as its N(n‐Bu) 4 + salt and characterized by 10 B, 11 B, and 19 F NMR spectroscopy, electrospray mass spectrometry, cyclic voltammetry, single‐crystal X‐ray diffraction, and calculations at the DFT level of theory. The B 24 F 22 4− anion has idealized D 5 symmetry and consists of two B 12 F 11 2− icosahedra linked by a 2c–2e boron–boron single bond with a BB distance of 1.725(4) Å. In the solid state, the anion interacts with eight N(n‐Bu) 4 + cations via a network of 34 CH···FB hydrogen bonds with H· · ·F distances that range from 2.26 to 2.55 Å. These hydrogen bonds were successfully modeled by DFT calculations, which showed that the hydrogen bonds probably have a measurable, albeit subtle, effect on the structure of the B 24 F 22 4− . © 2006 Wiley Periodicals, Inc. Heteroatom Chem 17:181–187, 2006; Published online in Wiley InterScience ( www.interscience.wiley.com ). DOI 10.1002/hc.20220