GAS-PHASE CHARACTERIZATION BY PHOTOELECTRON-SPECTROSCOPY OF UNSTABILIZED ALPHA-UNSATURATED ARSINES - ETHYLIDENEARSINES AND ETHYLIDYNEARSINES

Primary unsaturated arsines, vinylarsine (1), prop-1-enylarsine (2), a nd ethynylarsine (3), prepared by a chemoselective reduction of the co rresponding dichloroarsines, have been characterized in the gas phase by their photoelectron (PE) spectra. Their base-induced rearrangements on solid K2CO3, in vacuum gas-solid reactions (VGSR) conditions, led, respectively, to ethylidenearsine (4), propylidenearsine (5), and eth ylidynearsine (6). For the first time, electronic structures of primar y alpha-unsaturated arsines and low-coordinate arsenic compounds are e videnced and the coherence with phosphorus analogues is confirmed. In particular, six narrow and well-resolved bands at 9.6, 10.6, 11.9, 12. 7, 14.0, and 15.4 eV are observed in the PE spectra of 1, and the spec trum of 3 exhibits three ionizations at 9.9, 10.6, and 11.6 eV. The sp ectra attributed to 4 and 5 display a broad band with a shoulder at 9. 6 and 10.3 eV and at 9.5 and 10.2 eV, respectively. Two well-resolved bands at 9.6 and 12.1 eV are observed for 6.