“…The vacuum lines, handling techniques, and spectrometers used in this study have been described elsewhere [4,5,7]. All solvents were commercial materials and were dried and purified by condensation prior to use (CH 2 Cl 2 , Fissons, P 4 O 10 ; THF, Fissons, Na; SO 2 , BOC, CaH 2 ; SO 2 ClF, Aldrich, CaH 2 ; HF, Merck, BiF 5 ).…”