Sulphur chloride pentafluoride adds to certain olefins and chloro-olefins to give 2-chloroalkylsulphur pentafluorides ; acetylene and propyne give 2-chlorovinyl-and 2-chloropropenyl-sulphur pentafluoride, respectively. These products eliminate hydrogen chloride on treatment with potassium hydroxide, to give pentafluorosulphur-substituted olefins and acetylenes. SULPHUR CHLORIDE PENTAFLUORIDE does not react with paraffin hydrocarbons, but when heated under moderate pressures with certain olefins and chloro-olefins it adds to the double bond, giving 2-chloroalkylsulphur pentafluorides :This reaction has been carried out with ethylene, propene, cyclohexene, butadiene, and vinyl chloride; it failed with isobutene and styrene because these olefins polymerised very rapidly in the presence of sulphur chloride pentafluoride. Ethylene and vinyl chloride also showed a tendency to polymerise, for the simple addition compounds were accompanied by smaller amounts of higher-boiling fractions from which compounds were isolated which were evidently telomers containing two molecules of the olefin. The 2-chloroalkylsulphur pentafluorides eliminated hydrogen chloride on treatment with potassium hydroxide, to give the corresponding unsaturated pentafluorosulphur compounds; however, it was not possible to remove more than one molecule of hydrogen chloride from 2,2-dichloroethylsulphur pentafluoride, and attempts to prepare the substituted acetylene from this compound only resulted in complete decomposition.Addition of sulphur chloride pentafluoride to propene gave a high yield of 2-chloropropylsulphur pentafluoride, the structure of which was established by showing that two isomeric pentafluorosulphur-substituted propenes were formed by elimination of hydrogen chloride whereas 2-chloro-l-methylethylsulphur pentafluoride could only give one compound :

The Raman spectrum of liquid osmium tetroxide at 60" C shows three frequencies : 335 cm-1 (broad, strong, depolarized) ; 954 (diffuse, weak, depolarized) ; and 965 (sharp, very strong, polarized). The infra-red absorption spectrum of the solid shows absorptions at 325 and 955cm-1. It is concluded that the shape of the OsO4 molecule is regular tetrahedral and the following assignments are made : vl(A1), 965 cm-1; vz(E) and V4(F2), approximately 335 cm-1; v3(F2), 954 cm-1. Reasons are given for the fortuitous nearequality of v2 and v4. The Raman spectra of the perrhenate and tungstate ions in aqueous solution are closely similar to that of liquid Os04, whence it is concluded that the ions in solution are tetrahedral (ReO4-and WO42-respectively) and not, as had been previously suggested, octahedral due to co-ordination of water molecules.

The Raman spectrum of sulphur tetrafluoride in the liquid state at -60" C is photographed and the infra-red absorption of the gas at room temperature is recorded for the range 400-5O0Ocm-1. Considerations based upon selection rules, states of polarization of Raman lines and infra-red band contours exclude highly symmetrical models and support the conclusion that the point group is C2v. An assignment of frequencies on the basis of C20 symmetry is proposed. TABLE RA RAM AN AND INFRA-RED SPECTRA OF SULPHUR TETRAFLUORIDE Raman Av (cm-1) 239 w. 401 V.W. 463 m. depol. 536 V.S. depol. '/? )w., v. br. 760 858 m. depol. 898 V.S. pol. infra-red v (cm-1) (-235)* -463 V.W. 532 s. PQR 557 m. PQR (-645)* 715 m. 728 V.S. PQQR 768 867 v.s.PQR 889 V.S. PQR 961 V.W. 1070 V.W. 1091 w. 1098 w. 1114 w. 1125 V.W. 1177 V.W. 1281 m. PQR 1369 V.W. 1421 w.

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