SELENIUM SULFUR DIHALIDES, CHNX2 (N = 1, 2, 3 CH = SE, S X = BR, CL) - RAMAN AND SE-77 NMR SPECTROSCOPIC CHARACTERIZATION

Solutions of Se2Cl2 in S2Cl2, Se2Br2 in S2Cl2, Se in S2Cl2, and S in Se2Cl2 have been studied by Raman and Se-77 NMR spectroscopy. Selenium sulfur dihalides, SeSC12, SeSBr2, and SeSBrCl, formed in these solutions, have been shown by Raman and Se-77 NMR spectroscopy to have chain structures. Solutions of Se2Cl2 in S2Cl2, S in Se2Cl2, and Se in S2Cl2 have been shown to contain, in addition to Se2Cl2, S2Cl2, SeSCl2, Se3Cl2, and S8, trichalcogen dichlorides Se2SCl2 and SeS2Cl2. Selenium-77 signals corresponding to all seven chain isomers of the expected Se-containing dichalcogen dihalides, Se2Br2, Se2Cl2, Se2BrCl, SeSCl2, SeSBr2, BrSeSCl, and ClSeSBr, have been observed in the spectrum of a 1:1 molar mixture Of S2Cl2 and Se2Br2. The disulfur dichloride and dibromide, as well as the bromide chloride, are also present. Selenium-bromine and sulfur-chlorine linkages are observed-to be preferred over selenium-chlorine and sulfur-bromine bonding in these mixtures. The Se-77 chemical shifts correlate well with the electronegativity of the directly bonded neighbour but inversely with that of the next-nearest neighbour.