Direct IR spectroscopic study of the cyclopentadienyl radical

The products of vacuum pyrolysis of bis(cyclopentadienyl)nickel have been studied by matrix isolation infrared spetroscopy. Three IR bands at 3079, 1383 and 661 cm^–1 corresponding to the cyclopentadienyl radical have been observed. A comparison of the IR spectrum of the radical C₅H₅ with those of the ligand -C₅H₅ and free anion^–C₅H₅ has been performed.These results were presented for the first time in O. M. Nefedov's plenary lecture at X IUPAC Conference on Physical Organic Chemistry (Haifa, Israel, August 1990) (see ref. 1 and literature cited therein).Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 8, pp. 1497–1499, August, 1993.