Unmasking the Optimal Isomers of Ti₂C₈₄: Ti₂C₂@C₈₂ Instead of Ti₂@C₈₄

Abstract

Up to now, the controversies over the stable structures of endohedral di-metallofullerenes M2Cn, whether M2@Cn or M2C2@Cn–2, have continued ceaselessly. Herein, to disclose the optimal structures of Ti2C84, density functional theory combined with statistical thermodynamic analysis is performed in detail and it turns out that isolated pentagon rule C82 with Ti2C2 inserted wins overwhelmingly and performs close-shell electronic structure after our detailed analysis. Furthermore, the stimulation of UV–vis–NIR absorption spectra of thermodynamics preferred isomers under polarizable continuum models shows better accordance to the experimental spectra to reconfirm our result again. And 13C NMR spectra of three more stable isomers are performed for further investigations on geometry structures. Last but not least, the electronic structures and various interactions of thermodynamically optimum structures are further revealed.