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How large a 3 J HCCH coupling can be? Prediction of giant vicinal couplings in quinonoid systems
Author(s) -
NavarroVázquez Armando
Publication year - 2020
Publication title -
magnetic resonance in chemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.483
H-Index - 72
eISSN - 1097-458X
pISSN - 0749-1581
DOI - 10.1002/mrc.5037
Subject(s) - chemistry , vicinal , propagator , polarization (electrochemistry) , atomic orbital , density functional theory , computation , computational chemistry , coupling (piping) , molecular physics , chemical physics , quantum mechanics , physics , electron , mechanical engineering , organic chemistry , algorithm , computer science , engineering
Second‐order polarization propagator approximation (SOPPA) and density functional theory (DFT) B3LYP computations revealed the presence of giant 3 J HCCH couplings, up to more than 60 Hz, in conjugated quinonoid systems, very far above the typical limit of ~15 Hz. Strong hyperconjugative interactions of the C–H σ orbitals with the quinonoid 8‐e − π system, which allows effective propagation of the spin polarization, seem to be responsible for those extraordinarily large couplings. Computation on several model systems showed the additive nature of the contributions from the available coupling paths to the total coupling.