Solubility of I2 and formation of I2-arene charge-transfer complexes in supercritical SF6

The solubility of I-2(s) has been measured spectrophotometrically in supercritical SF6 with and without the addition of benzene and mesitylene at temperatures, T = 323.95, 330.00 and 340.55 K over the pressure range 2-10 MPa. It was possible to obtain the solubility of iodine and the concentration of the charge-transfer complex from the visible and UV bands of the spectra over the fluid density range 1.0-9.1 mol dm(-3). The results support the view that interactions between iodine and the arene molecules are restricted to Lennard-Jones plus multipole interactions. The observed variation with fluid density of the equilibrium concentration quotient for charge-transfer complex formation may be correlated with the density dependence of the excess number of I-2-arene collisions. No evidence for the existence of critical clustering has been found.