Matrix-isolation infrared and ultraviolet–visible studies on some transition-metal pentachlorides and pentabromides

Abstract

Samples of the solids NbCl₅, NbBr₅, TaCl₅, TaBr₅, ReCl₅, ReBr₅ and OsCl₅ have been vaporised in vacuo, and the products characterised by mass spectrometry and IR and UV/VIS spectroscopy in low-temperature argon and nitrogen matrices. In particular it is shown that vaporisation of the d⁰ species leads to the production of simple monomers, which adopt a square-pyramidal shape in nitrogen and a variety of conformers in argon. Rhenium pentachloride vaporises as a monomer which exhibits D_3h symmetry in both argon and nitrogen, but ReBr₅ and OsCl₅ decompose, the former to yield molecular Re₃Br₉.