Synthesis and Reactivity of Fluorinated Triaryl Aluminum Complexes

The addition of the Grignard 3,4,5-Ar^FMgBr to aluminum­(III) chloride in ether generates the novel triarylalane Al­(3,4,5-Ar^F)₃·OEt₂. Attempts to synthesize this alane via transmetalation from the parent borane with trimethylaluminum gave a dimeric structure with bridging methyl groups, a product of partial transmetalation. On the other hand, the novel alane Al­(2,3,4-Ar^F)₃ was synthesized from the parent borane and trimethylaluminum. Interestingly, the solid-state structure of Al­(2,3,4-Ar^F)₃ shows an extended chain structure resulting from neighboring Al···F contacts. Al­(3,4,5-Ar^F)₃·OEt₂ was then found to be an effective catalyst for the hydroboration of carbonyls, imines, and alkynes with pinacolborane.