Hydrogen-bonding effects on electronic g-tensors of semiquinone anion radicals : relativistic density functional investigation

• we report results of systematic g-tensor calculations of hydrogen-bonded complexes of two benchmark semiquinone anion radicals, 1,4-benzoquinone and tetramethyl-1,4-benzoquinone (duroquinone), with water and methanol molecules, The calculations have been carried out with the help of a recently developed g-tensor module that is based on a relativistic density functional method that takes spin-orbit interaction self-consistently into account. We demonstrate the applicability of this new computational scheme to describe quantitatively delicate effects, of hydrogen bonding on electronic g-tensor values. Also, we explored general trends of how g-tensors depend on the structure and stoichiometry of hydrogen-bonded semiquinone complexes. Complexes exhibiting one hydrogen bond per oxygen atom of the quinones with a linear arrangement of the C=(OH)-H-... moieties were. shown to feature g-shifts induced by these hydrogen bonds that are in close agreement with measured electron paramagnetic resonance data. Based on deviations of calculated and measured g-components, we classify all other model complexes Studied as less probable Under the experimental conditions.

Nyckelord

g-tensors

hydrogen bonding

semiquinone anion radicals

EPR spectroscopy

molecular g-tensors

hyperfine couplings

ab-initio

approximation

energy

resolution

behavior

orbitals

epr

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