Properties and reactions of uranium(IV) tetrahydroborate by ion cyclotron mass spectrometry

The gas-phase ion chemistry of U(BH4)4 is studied with the techniques of ion cyclotron resonance spectrometry. An electron impact ionization energy of 9.0 +- 0.5 eV is determined, and appearance energies for several positive fragment ions are reported. These data are analyzed to give ΔH/sub f/[U(BH4)4] = -7 +- 14 kcal/mol as well as several bond dissociation energies for the parent neutral and its fragment ions. U(BH4)4 attaches thermal electrons to form the molecular anion. Fragment negative ions are observed with higher energy electrons. The reactions of both positive and negative ions in U(BH4)4 alone and with other gases are reported. The trapped-electron spectrum is obtained and compared with previous optical spectroscopic studies of U(BH4)4. Irradiation of major positive ions by a low-power CW CO2 laser produced no evidence of photochemistry