The NICS (Nucleus-Independent Chemical Shift) as a probe of the relative stability of beta-chalcogenovinylaldehydes stabilized through intramolecular chalcogen-chalcogen interactions

摘要

Density functional calculations, at the B3LYP/6-311+G(3df,2p) level, have been carried out for the complete series of beta-chalcogenovinylaidehydes, CH(X)-CH=CH-YH (X, Y=O, S, Se, Te), to estimate the strength of H-X center dot center dot center dot Y or X center dot center dot center dot Y-H intramolecular chalcogen-chalcogen interactions, through the use of appropriate homodesmotic reactions. For the same set of compounds the value of the nucleus-independent chemical shift (NICS), on points I A above the corresponding ring critical point, has been obtained at the B3LYP/6-311 + G(3df,2p) level. For non-stabilizing chalcogen-chalcogen interactions the NICS value is positive, while the opposite is found when the interaction is stabilizing. In general, there is a good linear correlation between both magnitudes and therefore, we can conclude that NICS value is a reliable probe of the strength of intramolecular chalcogen-chalcogen interactions in this set of compounds. (c) 2005 Elsevier B.V. All rights reserved.