Surprising Stability of an Al/P-Based Frustrated Lewis-Pair Towards Protolysis: HX Adducts (X = F, Cl) with Intramolecular H•••X Hydrogen Bonds

The Al/P-based Frustrated Lewis Pair (FLP) Mes(2)P-C(=CH-Ph)-Al(CMe3)(2) (1) reacted with anhydrous HF and HCl as an ion pair receptor by coordination of the proton to phosphorus and the halide anion to aluminum. Short intramolecular distances and the molecular conformation indicate the presence P-H center dot center dot center dot X-Al hydrogen bonds (X = F, Cl) and an approach of the phosphorus and halogen atoms with a possible weak P center dot center dot center dot X interaction.