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 D3h symmetry in both argon and nitrogen, but ReBr5 and OsCl5 decompose, the former to yield molecular Re3Br9.