Spectroscopic studies on matrix isolated tungsten chlorides and bromides

Abstract

Tungsten pentachloride has been heated in high vacuum, and the vapour species isolated in inert matrices at ca. 12 K. Subsequent i.r. spectra showed intense features at 410 and 365 cm^–1 which are assigned as the A₂″ and E′ stretching modes respectively of monomeric D_3h WCl₅. Corresponding studies on the hexachloride showed that monomeric WCl₆ could similarly be isolated, and for this species, the u.v.–visible spectrum was also obtained and analysed in detail. The vaporisation of tungsten bromide samples of typical stoicheiometry WBr_5.3 yielded a new spectroscopic feature in the matrix i.r. spectrum at ca. 305 cm^–1 which is assigned to molecular WBr₆. At higher temperatures, the vaporisation of the solid pentabromide resulted in bands at 280 and 245 cm^–1 which are assigned as the A₂″ and E′ stretching modes in D_3h WBr₅.