A spectroscopic examination of phenyltellurium trihalides

Abstract

The far-i.r. spectra, and where possible the Raman spectra, of RTeX₃ are presented and assigments of tellurium–halogen modes are made (R = Ph, p-Me·C₆H₄, p-MeO·C₆H₄, p-EtO·C₆H₄, p-PhO·C₆H₄; X = Cl, Br, or I). Consideration of the low-frequency vibrational data and other physical evidence suggests the compounds are associated to some degree with dimeric structures involving five-co-ordinate tellurium atoms the most probable for chlorides and iodides. There is evidence to suggest that some bromides notably PhTeBr₃, (p-Me·C₆H₄)TeBr₃, and (p-PhO·C₆H₄) TeBr₃ are more associated. It is suggested that the variety of structural possibilities are best understood in terms of donor–acceptor interactions between X^– and RTeX₂⁺.