(m), -137.3 (m)), which was assigned as [(C6F5CF3)P n Bu3] + ([16] + ). Also, when bromopentafluorobenzene was used as a substrate, the formation of the phosphonium salt [C6F5P n Bu3]Br ([14]Br) was observed under catalytic conditions, and its concentration could be increased by addition of an extra 0.9 equiv. of P n Bu3, as described above and shown in Scheme 3.