Flash vacuum thermolysis of 3,4-dimethyl-1-germacyclopent-3-enes: UV photoelectron spectroscopic characterization of GeH2 and GeMe2

Gas‐phase UV photoelectron spectra of germylene (GeH2) and its dimethyl analogue (GeMe2) have been recorded, using flash vacuum thermolysis of 3,4‐dimethyl‐ and 1,1,3,4‐tetramethyl‐germacyclopent‐3‐ene to generate these reactive species in the inlet of the photoelectron spectrometer. The lowest vertical ionization bands for GeH2 (9.4 eV) and GeMe2 (8.2 and 10.0 eV) have been located with the aid of time‐dependent density functional theory calculations carried out at the B3LYP/6‐311G(d,p) level of theory. Similar experiments carried out with 3,4‐dimethyl‐1,1‐diphenylgermacyclopent‐3‐ene, in an attempt to record the photoelectron spectrum of diphenylgermylene (GePh2), were less conclusive, but are consistent with the theoretically predicted lowest lonization potential of 8.0–8.2 eV for GePh2. Photoelectron spectra of the three germacyclopentene derivatives are also reported. Copyright © 2004 John Wiley & Sons, Ltd.