Watson Peter D, McKinley Allan J, Wild Duncan A
School of Molecular Sciences, The University of Western Australia, Crawley, Western Australia 6009, Australia.
J Phys Chem A. 2022 May 26;126(20):3072-3079. doi: 10.1021/acs.jpca.2c00299. Epub 2022 May 12.
Anion photoelectron spectroscopy has been used to investigate the structure and dynamics of CHOOI van der Waals complexes. Peaks within the photoelectron spectrum are attributed to photodetachment to the perturbed P state of I···CHOO (3.46 eV) and the two P states of bare iodine. A broad feature at 1.7-2.4 eV is attributed to detachment to the excited singlet states from two O···CHI 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 O. Interactions are dominated by electrostatics, with the anion species interacting with the methyl pocket of the solvating molecule, suggesting conversion via an 2 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.
阴离子光电子能谱已被用于研究CHOOI范德华复合物的结构和动力学。光电子能谱中的峰归因于光剥离到I···CHOO的受扰P态（3.46电子伏特）和裸碘的两个P态。1.7 - 2.4电子伏特处的一个宽峰归因于从两个O···CHI复合物光剥离到激发单重态。这是卤化物结合的甲基过氧自由基物种的首次阴离子光电子能谱研究。使用MP2/aug - cc - pVQZ对复合物结构进行了优化，对于基态复合物，在W1w理论下计算单点能量，对于光剥离到激发态O则使用NEVPT2。相互作用主要由静电作用主导，阴离子物种与溶剂化分子的甲基口袋相互作用，表明通过一种2机制进行转化，并且过量能量导致在质谱时间尺度内复合物解离。计算得到的W1w吉布斯自由能表明，虽然存在电子转移（ET）转化途径，但相对不利。
