Halogenation of Dibenzoselenophene and Dibenzo[1,2]diselenine

The syntheses of the selenium containing heterocycles di-benzoselenophene (1 = biphenSe) and dibenzo[1,2] diselenine (2 = biphenSe(2)) were optimized. The halogenation reactions of 1 and 2 with XeF2, SO2Cl2, 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 center dot 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 biphen-SeO center dot HF (3a) upon storage in glass vessels at low temperatures. In the case of 2, the selenium(IV) trihalogenides, biphen(SeHal(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 Se2Cl2, SeCl4 and 1 were detected. In the case of Hal = I, the stable adduct biphenSe(2)center dot I-2 (7) was isolated. In addition to characterization by multinuclear NMR spectroscopy, several molecular structures of biphen-selenium substituted halogenides were determined.