Regioselectivity in azahydro[60]fullerene derivatives: application of general-purpose reactivity indicators.
To attempt theoretical predictions of the regioselectivity pattern in molecules with multiple reactive sites, the energies of formation of all possible isomers are usually considered. This means that the computing becomes highly demanding if high theoretical levels are used. The study objective was to predict the regioselectivity in the reaction of hydrogen addition onto azahydro[60]fullerene C 59H n+1 N ( n = 0-4) systems using a new reactivity indicator termed general-purpose reactivity indicator, Xi Delta N<or=0,alpha (kappa), proposed by Anderson et al. ( J. Chem. Theory Comput. 2007, 3, 358). Because Xi Delta N<or=0,alpha (kappa) combines the information from the electrostatic potential and the Fukui function, this indicator is a two-parameter model that depends on the atomic charges and Fukui values calculated. We used the gradient-corrected BLYP and BOP functionals to approximate the electronic density of the systems, and these densities were employed to determinate the parameters. In terms of regioselectivity, the preferential addition sites at every hydrogenation step on C 59H n+1 N ( n = 0-4) shows that 1,4-adducts are more stable than 1,2-adducts. However, we show that the multiple additions are only feasible up to a C 59H 5N (tetraddition) product. Consequently, the application of this indicator not only helps to avoid systematic computational studies by comparing energies of formation in several isomersmany of which are not currently supported by experimental resultsbut also provides an insight of how the pattern of addition is achieved. Comparisons with traditional indicators show that the application of Xi Delta N<or=0,alpha (kappa) performs much better for predicting reactivity in the aza[60]fullerene derivatives studied.
Contreras-Torres
Flavio F
FF
Centro de Ciencias Aplicadas y Desarrollo Tecnologico, Universidad Nacional Autonoma de Mexico, Circuito Exterior C. U., 04510 Mexico D.F., Mexico. flavioc@nucleares.unam.mx
Basiuk
Vladimir A
VA
Basiuk
Elena V
EV