Affiliation:
1. Paul Scherrer Institute: Paul Scherrer Institut PSI Photon Science SWITZERLAND
2. Tohoku University - Katahira Campus: Tohoku Daigaku Institute of Fluid Science JAPAN
3. Paul Scherrer Institut Molecular Dynamics WSLA/028 5232 Villigen PSI SWITZERLAND
Abstract
Understanding how isomerism influences photoelectron spectra helps in the assignment and analysis of reactive mixtures, especially for heterocycles with numerous isomers. Threshold photoelectron spectra of lutidyl radical isomers, i.e., benzyl derivatives with a nitrogen heteroatom and a methyl substituent, are recorded using vacuum ultraviolet synchrotron radiation. The radicals are produced by flash pyrolysis from aminomethyl methylpyridine precursors. Experimental ionization energies are determined to be 7.54, 7.50, and 7.45 eV for 2,4‐, 2,6‐ and 3,5‐lutidyl, respectively, in excellent agreement with composite method calculations. Franck– Condon simulations aid the TPES assignment but are also shown to exhibit artifacts if large‐amplitude motions, notably the methyl internal rotation are assumed to be active in the double harmonic approximation. Based on calculated adiabatic ionization energies (AIE) of benzyl, picolyl, and xylyl radicals, the N and CH3 substituent effects are found to be additive, position‐dependent and decrease in the para > ortho ≳ meta order in magnitude with the nitrogen heteroatom increasing and the methyl substituent decreasing the AIE. These effects are discussed in light of the charge distribution upon ionization. The additivity of the substituent effects also helps predict the influence of substituents on the binding energy of the unpaired electron in analogous radicals.
Subject
Physical and Theoretical Chemistry,Atomic and Molecular Physics, and Optics
Cited by
1 articles.
订阅此论文施引文献
订阅此论文施引文献,注册后可以免费订阅5篇论文的施引文献,订阅后可以查看论文全部施引文献