Photochemically and Thermally Generated BN-Doped Borafluorenate Heterocycles via Intramolecular Staudinger-Type Reactions.

A series of BN-incorporated borafluorenate heterocycles, bis(borafluorene-phosphinimine)s ( 11 - 15 ), have been formed via intra molecular Staudinger-type reactions. The reactions were promoted by light or heat using monodentate phosphine-stabilized 9-azido-9-borafluorenes (R 3 P-BF-N 3 ; 6 - 10 ) and involve the release of dinitrogen (N 2 ), migration of phosphine from boron to nitrogen, and oxidation of the phosphorus center (P III to P V ). Density functional theory (DFT) calculations provide mechanistic insight into the formation of these compounds. Compounds 11 - 15 are blue emissive in the solution and solid states with absolute quantum yields (Φ F ) ranging from 12 to 68%.