Supplementary information 1 from Structure and reactivity of an Al/P-based frustrated Lewis pair bearing relatively small substituents at aluminium

Reaction of Mes<sub>2</sub>P-C≡C-Ph (Mes = mesityl) with dineopentylaluminium hydride afforded by hydroalumination a geminal Al/P-based frustrated Lewis pair (FLP; <b>4</b>). Its steric shielding is relatively low, and its reactivity in various secondary reactions is less hindered by steric repulsion than observed for related compounds having bulkier groups attached to aluminium. <b>4</b> yielded adducts (<b>5</b> and <b>6</b>) with Me<sub>3</sub>C-NCO or benzaldehyde via the formation of Al–O and P–C bonds. Trimetylsilyl azide reacted with <b>4</b> under surprisingly mild conditions to afford a nitrene complex by spontaneous N<sub>2</sub> elimination below room temperature. A carbodiimide molecule was coordinated via one of the C=N bonds to form a five-membered AlCPNC heterocycle with an intact C=N bond in an exocyclic position. A very large molecule was obtained by the reaction of two equivalents of <b>4</b> with a bifunctional methylene-bridged phenylene isocyanate precursor.