Reactions of Carbaalanes with HBF4 and HCl: A μ3-Bridging Fluorine Atom in (AlEt)7(CCHPh)2(CCH2Ph)3(μ3-F) versus a Terminal Chlorine Atom in (AlMe)7(AlCl)(CCH2Ph)5H

The carbaalane cluster (AlEt) 7 (C CHC 6 H 5 ) 2 (CCH 2 C 6 H 5 ) 3 H ( 2 ) reacted with HBF 4 ·OEt 2 to yield the fluorine derivative (AlEt) 7 (C CHC 6 H 5 ) 2 (CCH 2 C 6 H 5 ) 3 (μ 3 -F) ( 4 ) by the replacement of its bridging hydrogen atom and the cleavage of a B−F bond. The fluorine atom bridges three aluminum atoms with the Al−F distances in a narrow range between 1.97 and 2.00 Å. A similar reaction was observed with the arachno -carbaalane (AlMe) 8 (CCH 2 C 6 H 5 ) 5 H ( 1 ). However, an impure product was isolated which could not be purified by repeated recrystallization. In contrast, use of HCl instead of HBF 4 ·OEt 2 as a proton donor did not result in substitution of the bridging hydrogen atom of 1, but a methyl group at the bottom of the cluster was replaced by release of methane. The compound (AlMe) 7 (AlCl)(CCH 2 C 6 H 5 ) 5 (μ-H) ( 6 ), which possesses a terminally bonded chlorine atom, was formed.