Quantum Chemical Insight into La2C96: Metal Carbide Fullerene La2C2@C94 versus Dimetallofullerene La2@C96.

A family of dilanthanum-containing endohedral metallofullerene La2C2n (n = 46-51) was synthesized recently. In the present work, a systematical investigation on La2C96 series including the carbide clusterfullerene form La2C2@C94 and the conventional dimetallofullerene form La2@C96 was implemented by density functional theory, combined with statistical mechanics. Three isomers, i.e., La2@D2(191838)-C96, La2C2@Cs(153479)-C94, and La2C2@C1(153491)-C94 were disclosed to be thermodynamically stable at the temperature region of endohedral metallofullerene formation. La2@D2(191838)-C96 is the prevailing isomer at low temperature, while La2C2@Cs(153479)-C94 and La2C2@C1(153491)-C94 are the most and second-most abundant isomers at high temperature. Interestingly, the highest occupied molecular orbital (HOMO) of La2C2@C1(153491)-C94 is distributed on one pole of the cage, and the lowest unoccupied molecular orbital (LUMO) of this isomer is mainly located on the equator of the cage, which can facilitate synthesis of regioselective derivatives. This work will provide useful information for further experimental identification and application of La2C96.