Bingel–Hirsch reaction mechanisms on TiSc2N@Ih-C80: the role of endohedral titanium nitride

Abstract

Recently, two unconventional singly bonded monoadducts of mixed-metal nitride clusterfullerene TiSc₂N@I_h-C₈₀ have been synthesized. Herein, the site-selectivity and kinetic processes of Bingel–Hirsch reactions are explored by density functional theory calculations. Because of the rotation of the inner TiSc₂N unit, two different types of singly bonded monoadducts (named 666 and 566 adducts) are clarified. Meanwhile, the two functionalized sites are situated above the Ti–Sc edge of the inner cluster in singly bonded adducts. Addition on the triple-fused-hexagon site (6–6–6 site) is found to be kinetically preferred, which can be attributed to the more positive charge of the carbon in the 6–6–6 site. In addition, we investigated the formation process of two conventional cycloadducts. A preference for the addition on the bridged hexagon–hexagon bond is concluded in theory, furthermore, one Sc atom instead of the Ti atom is pointing to the functionalized bond for the lowest-energy orientational product.