Reactivity of Oxygen‐Bridged Geminal Al/P and Si/P Frustrated Lewis Pairs towards Heterocumulenes

Abstract

AbstractThe two oxygen‐bridged geminal frustrated Lewis pairs (FLP) tBu2P−O−AlBis2 (Bis=CH(SiMe3)2; 1) and tBu2P−O−Si(C2F5)3 (2) were reacted with the heterocumulenes PhNCO, PhOCN, PhNCS, CS2 and PhNSO as well as SO2. With isocyanate and cyanate, both 1 and 2, form addition products under formation of five‐membered rings. With CS2, isothiocyanate and sulfinylaniline, only 1 forms stable adducts, whereas 2 shows reactivity towards sulfinylaniline, but the product decomposed after a few minutes. The reaction of 1 with SO2 led to partial cleavage of the P−O−Al and Al−C units, as confirmed by X‐ray diffraction studies of a complex aggregate. The reaction of 2 with SO2 affords the 1,2‐addition product. All adducts were characterized by means of multinuclear NMR spectroscopy, X‐ray crystallography and CHN analyses.