Photoelectron Spectroscopy and High-Level Ab Initio Calculations of the Iodide–Methylperoxy Radical Complex

Abstract

Anion photoelectron spectroscopy has been used to investigate the structure and dynamics of CH₃OOI^– van der Waals complexes. Peaks within the photoelectron spectrum are attributed to photodetachment to the perturbed ²P_3/2 state of I$\cdots$CH₃OO (3.46 eV) and the two ²P states of bare iodine. A broad feature at 1.7–2.4 eV is attributed to detachment to the excited singlet states from two O₂^–$\cdots$CH₃I complexes. This represents the first anion photoelectron spectroscopy of a halide-bound methylperoxy radical species. Complex structures have been optimized using MP2/aug-cc-pVQZ with single-point energies at W1w theory for ground-state complexes and NEVPT2 for photodetachment to excited O₂. Interactions are dominated by electrostatics, with the anion species interacting with the methyl pocket of the solvating molecule, suggesting conversion via an S_N2 mechanism, and excess energy leading to complex dissociation within the timescale of mass spectrometry. The calculated W1w Gibbs energies suggest that while an electron transfer (ET) pathway to conversion is available, it is comparatively unfavored.

Peter Watson

Forrest Fellow, Lecturer

My research interests include distributed robotics, mobile computing and programmable matter.