Synthesis and Reactivity of Fluorinated Triaryl Aluminum Complexes.

The addition of the Grignard 3,4,5-ArMgBr to aluminum(III) chloride in ether generates the novel triarylalane Al(3,4,5-Ar)·OEt. 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) was synthesized from the parent borane and trimethylaluminum. Interestingly, the solid-state structure of Al(2,3,4-Ar) shows an extended chain structure resulting from neighboring Al···F contacts. Al(3,4,5-Ar)·OEt was then found to be an effective catalyst for the hydroboration of carbonyls, imines, and alkynes with pinacolborane.