Compounds bearing a heterosubstituted double or triple bond such as ethenol, ethynol, ethenamine, or ethynamine have been the subject of extensive theoretical investigations.2 However, due to the high instability of these compounds, the experimental characterizations of the unsubstituted parent molecules have been performed either in matrix3 or in the gas phase by mass or photoelectron spectroscopy4 (PES). To our knowledge similar studies on phosphorus compounds are limited to ethenylphos-phinesS5 We report here our results on the gas-phase structure and reactivity of alkynyl-and allenylphosphines monitored by photoelectron spectroscopy.
PE Spectra of Akyayland AllenylpbosphinesAlkynyl-and allenylphosphines are cleanly produced by mild reduction with dichloroalane (AlHCh) in tetraglyme of the corresponding alkynyl-or allenylphosphonates, respectivelye6 The reductions are performed on a vacuum line directly connected, via a cryogenic trap, to the PES inlet. In this way the volatile phosphines are continuously distilled,from the reaction mixture to the cryogenic trap (100 K). After subsequent heating of the trap to the suitable temperature, the analysis of the phosphines is completed by recording the PE spectra of the gaseous flow. This gaseous flow may also be trapped on a cold finger fitted to an NMR tube, bypassing the PES inlet. The NMR spectra of (1) Application of Photoelectron Spectroscopy to Molecular Properties. 46. Part 45: Chuburu, F.; Lacombc, S.; Wster-Guillouzo, G.; Ben Cheik, A,; Chuche, J.; Pommelet, J. C.