Probing hypervalent radicals by neutralization - Laser photoionization mass spectrometry

The metastability of hypervalent dimethyldeuteroxonium radicals (1a(.)), generated by fast collisional electron transfer from organic targets in the gas phase, is probed by laser photoionization at 488 and 514.5 nm. A fraction of 1a(.) is photoionized at these wavelengths, indicating formation of metastable 1a(.) with vertical ionization energies of <2.5 eV. Ab initio calculations find a bound (2)A'' state for dimethylhydroxonium 1b(.), which is characterized as a 3p Rydberg state of 2.22 eV vertical ionization energy. No potential energy minimum is found for the (2)A' ground electronic state of 1a,b(.), which is predicted to dissociate exothermically by O-H bond cleavage.