Rhenium(III) chloride vaporisation and vapor complexation in the rhenium(III) chloride–aluminium(III) chloride systemElectronic Supplementary Information available. See http://www.rsc.org/suppdata/cp/b1/b106326j/

Abstract

The colored vapors over solid rhenium(III) chloride, Re3Cl9(s), have been investigated spectrophotometrically at temperatures up to 825 K. The data obtained were used: (a) to measure the molar absorptivity of Re3Cl9 vapors; (b) to determine the vapor pressure of solid rhenium(III) chloride in the temperature range 675–825 K and (c) to establish the thermodynamic functions of the vaporization Re3Cl9(s)↔Re3Cl9(g): ΔHo=199±9 kJ mol−1, ΔSo=221±13 J mol−1 K−1. Raman spectra of Re3Cl9 vapors and vapors of the binary system Re3Cl9–Al2Cl6 were recorded at temperatures up to 825 K in order to study the structural and vibrational properties of the rhenium(III) containing gaseous species. The existence of a Re3 cluster can be inferred from the Raman spectra for both Re3Cl9(g) and the Re–Al–Cl vapor complex formed in the binary system. Raman bands for the Re–Re stretching vibration are observed at 260 cm−1 for gaseous Re3Cl9 and 264 cm−1 for the Re–Al–Cl vapor complex. The Raman spectral features indicate that the vapor complex is formed according to the reaction: Re3Cl9(s)+3/2Al2Cl6(g)↔Re3Cl9(AlCl3)3(g).