Exploring Electronic Properties of Si_20-nH_20-nP_n Heterofullerenes (N = 1, 2, 5, and 10) Based on NMR and NBO Analysis: A DFT Study

Abstract

Density functional theory (DFT) calculations are performed to characterize Si_20-nH_20-nP_nheterofullerenes (n = 1, 2, 5, and 10), and to examine the stability of encapsulated X@Si_20-nH_20-nP_nwhere X = Li, Na, and K. To this aim, ²⁹Si, ³¹P, and ¹H chemical shielding (CS) tensors as well as natural charges are calculated for the optimized structures. The local structures around silicon as well as phosphorus nuclei are found to show a good correlation with CSs. However, the similar values of ¹H calculated CSs (26–28 ppm) obtained for all the heterofullerenes mean hydrogen atoms do not detect the local structure around the adjacent silicon and also do not distinguish between isomers of heterofullerenes and the number of P dopants. According to calculated endo-hedral inclusion energies (E_inc), formation of the Li@Si_20-nH_20-nP_ncomplexes, unlike the K@Si_20-nH_20-nP_nones, are exothermic while E_incof the Na@Si_20-nH_20-nP_ncomplexes strongly depends on the position and number of P dopants. Moreover, binding energies for the considered models are found to be in the order of Si_20-nH_20-nP_n> Li@Si_20-nH_20-nP_n> Na@Si_20-nH_20-nP_n> K@Si_20-nH_20-nP_nwhile strongly depending on the pattern of P dopants on the surface of the cage.

Supplemental materials are available for this article. Go to the publisher's online edition of Phosphorus, Sulfur, and Silicon and the Related Elements to view the following free supplemental files: Additional figures and tables]

GRAPHICAL ABSTRACT

Keywords:

• Si_20-n H_20-n P _n heterofullerenes
• chemical shielding (CS) parameters
• nuclear magnetic resonance (NMR)
• Natural Bond Orbital (NBO)
• density functional theory (DFT)