Shielding-density functions interpret nuclear magnetic shieldings point-wise, through the Biot–Savart law. For aromatic, antiaromatic, and non-aromatic p-systems (benzene, cyclooctatetraene, borazine), the characteristic pattern of current density leads to a distinctive map for the p-contribution to the perpendicular components of 1H shielding-density. Hence, global and localised currents have distinguishable signatures, dependent on separation between outward and return circulations in the current–density map. Aromatic, diatropic p-current produces an intense deshielding ipso spike, weakly cancelled by a remote shielding ridge; paratropic anti-aromatic p-current inverts these features; localised p-currents produce cancelling shielding/deshielding spikes. Ringcurrents also contribute characteristically to out-of-plane carbon shieldings.
Ring-current signatures in shielding-density maps
ZANASI, Riccardo
2005
Abstract
Shielding-density functions interpret nuclear magnetic shieldings point-wise, through the Biot–Savart law. For aromatic, antiaromatic, and non-aromatic p-systems (benzene, cyclooctatetraene, borazine), the characteristic pattern of current density leads to a distinctive map for the p-contribution to the perpendicular components of 1H shielding-density. Hence, global and localised currents have distinguishable signatures, dependent on separation between outward and return circulations in the current–density map. Aromatic, diatropic p-current produces an intense deshielding ipso spike, weakly cancelled by a remote shielding ridge; paratropic anti-aromatic p-current inverts these features; localised p-currents produce cancelling shielding/deshielding spikes. Ringcurrents also contribute characteristically to out-of-plane carbon shieldings.I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
