Decisive investigations on stabilities of Sc2O@C-86 and Sc2S@C-86 isomers were carried out via density functional theory with statistical thermodynamic method. Sc-2 X@C-2v(63751)-C-86 and Sc2X@C-1(63755)-C-86(X = O and S), observing isolated pentagon rules, were confirmed as thermodynamically preferred isomers within fullerene-formation temperature. Particularly, it is the first time to acknowledge C1( )63755)-C(86 )as host for encapsulating Sc2X (X = 0 and S), herein. Interactions between Sc and nonmetal atoms in Sc2X@C-2v (63751)-C-86 and Sc2X@C-1(63755)-C-86(X = O and S) were specifically explored. Importantly, characteristics and electron density ellipticity for independent X-Sc (X = O and S) bonds and their bonding paths performed clear distinction due to weak intramolecular interaction. (C) 2018 Elsevier B.V. All rights reserved.