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Title: The one-electron oxidation of a dithiolate molecule: The importance of chemical intuition

A series of nine commonly used density functional methods were assessed to accurately predict the oxidation potential of the (C{sub 2}H{sub 2}S{sub 2}{sup −2}/C{sub 2}H{sub 2}S{sub 2}{sup •−}) redox couple. It was found that due to their greater tendency for charge delocalization the GGA functionals predict a structure where the radical electron is delocalized within the alkene backbone of C{sub 2}H{sub 2}S{sub 2}{sup •−}, whereas the hybrid functionals and the reference QCISD/cc-pVTZ predict that the radical electron remains localized on the sulfurs. However, chemical intuition suggests that the results obtained with the GGA functionals should be correct. Indeed, with the use of the geometries obtained at the HCTH/6-311++G(3df,3pd) level of theory both the QCISD and hybrid DFT methods yield a molecule with a delocalized electron. Notably, this new molecule lies at least 53 kJ mol{sup −1} lower in energy than the previously optimized one that had a localized radical. Using these new structures the calculated oxidation potential was found to be 2.71–2.97 V for the nine DFT functionals tested. The M06-L functional provided the best agreement with the QCISD/cc-pVTZ reference oxidation potential of 3.28 V.
Authors:
; ;  [1]
  1. Department of Chemistry, Dalhousie University, Halifax, Nova Scotia B3H 4R2 (Canada)
Publication Date:
OSTI Identifier:
22253467
Resource Type:
Journal Article
Resource Relation:
Journal Name: Journal of Chemical Physics; Journal Volume: 140; Journal Issue: 18; Other Information: (c) 2014 AIP Publishing LLC; Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
37 INORGANIC, ORGANIC, PHYSICAL AND ANALYTICAL CHEMISTRY; DENSITY FUNCTIONAL METHOD; ELECTRONS; FUNCTIONALS; HYBRIDIZATION; MOLECULES; OXIDATION