Finite-field calculations of non-linear induced current density in representative [4n + 2] and [4n] π systems, benzene and flat cyclooctatetraene (COT), show that a strong uniform perpendicular magnetic field enhances benzene π-diatropicity and decreases COT π-paratropicity. The non-linear current is stronger by two orders of magnitude in COT, but still small: at 1a 0 height and in a field of 25 T, third-order effects contribute -5 ppm to the first-order π ring current. Classical arguments based on radial contraction of charge density rationalise the non-linear response of benzene, but that of COT depends on a specific orbital-rotation effect, characteristic of paratropic π systems. © 2004 Elsevier B.V. All rights reserved.
Non-linear ring currents: Effect of strong magnetic fields on π-electron circulation
Soncini A.;
2004
Abstract
Finite-field calculations of non-linear induced current density in representative [4n + 2] and [4n] π systems, benzene and flat cyclooctatetraene (COT), show that a strong uniform perpendicular magnetic field enhances benzene π-diatropicity and decreases COT π-paratropicity. The non-linear current is stronger by two orders of magnitude in COT, but still small: at 1a 0 height and in a field of 25 T, third-order effects contribute -5 ppm to the first-order π ring current. Classical arguments based on radial contraction of charge density rationalise the non-linear response of benzene, but that of COT depends on a specific orbital-rotation effect, characteristic of paratropic π systems. © 2004 Elsevier B.V. All rights reserved.Pubblicazioni consigliate
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