A N3-geminal Al/P-Based Intramolecular Lewis Pair: Synthesis, Characterization and Reactivity

Frustrated Lewis pairs (FLPs) play a crucial role in main-group chemistry due to the diverse reactivities towards small molecules and extensive applications in organic transformations. The intramolecular FLP systems known in the literature are mainly consisted of boron-containing Lewis acids and the linkers are almost exclusively based on carbon. Herein, the nitrogen-linked geminal Al/P Lewis pair 1 was readily prepared by salt metathesis reaction between AlBr3 and N[CH2CH2NLi-PtBu2]3 in toluene at room temperature. Further studies confirmed that 1 exhibited typical FLP-type reactivity towards heterocumulenes, isocyanide and transition metal precursors. Single-crystal X-ray diffraction analysis revealed that all the addition products contained a penta-coordinated aluminum atom which was less common in FLP chemistry. This study demonstrated that the resulting Al/P-based system represented an efficient alternative class of FLPs and enriched the linker motifs of intramolecular FLPs.