The fluoro(perfluoropyridine)xenon( II ) cations, C 5 F 5 N–XeF + and 4-CF 3 C 5 F 4 N–XeF + ; novel examples of xenon as an aromatic substituent and of xenon–nitrogen bonding

The fluoro(perfluoropyridine)xenon(II) cations, 4-RC5F4N–XeF+(R = F or CF3), have been observed in HF and BrF5 solutions (stable up to –30°C) and their AsF6– salts have been isolated from BrF5 solutions; low temperature Raman and 129Xe, 19F, and 14N n.m.r. spectroscopic results are consistent with planar cations in which the xenon atom is co-ordinated to the aromatic ring through the lone pair of electrons on the nitrogen.