Halogenation of Dibenzoselenophene and Dibenzo[1,2]diselenine

The syntheses of the selenium containing heterocycles dibenzoselenophene ( 1 ≡ biphenSe) and dibenzo[1,2]diselenine ( 2 ≡ biphenSe 2 ) were optimized. The halogenation reactions of 1 and 2 with XeF 2 , SO 2 Cl 2 , Br 2 and I 2 were performed and the corresponding products characterized. In the case of 1 , the selenium(IV) dihalogenides, biphenSeF 2 ( 3 ), biphenSeCl 2 ( 4 ), biphenSeBr 2 ( 5 ), and the adduct biphenSe·I 2 ( 6 ), were isolated and identified. The extremely sensitive selenium(IV) difluoride 3 slowly formed significant amounts of an adduct with HF of the corresponding selenium(IV) oxide biphenSeO·HF ( 3a ) upon storage in glass vessels at low temperatures. In the case of 2 , the selenium(IV) trihalogenides, biphen(Se Hal 3 ) 2 ( Hal = F, Cl, Br), were found to be extremely labile ( Hal = F) or not detectable ( Hal = Cl, Br). Instead, as decomposition products, the selenium chloride species Se 2 Cl 2 , SeCl 4 and 1 were detected. In the case of Hal = I, the stable adduct biphenSe 2 ·I 2 ( 7 ) was isolated. In addition to characterization by multinuclear NMR spectroscopy, several molecular structures of biphen‐selenium substituted halogenides were determined.