Quantum-Chemical Study of Yb@C60, Yb@B2C58, and Gd@B3C57 Molecules

Using the DFT PBE0/SDD method, the structural parameters of the Yb@η2-C60, Yb@η6-C60, Yb@η6-B2C58, and Gd@η6-B3C57 molecules, of corresponding anions (1,4-B2C58)2–, (1,3,5-B3C57)3–, and free radicals BkC60–k were calculated. Ytterbium is coordinated by the degraded C=C bond in the Yb@η2-C60 molecule and by the 1,4-diboratacyclohexa-1,3,5-triene fragment, in Yb@η6-B2C58. Symmetric substitution of three atoms of the cyclohexa-1,3,5-triene fragment leads to the formation of cyclopropane fragment, three 1,4-diboratacycloocta-1,3,5,7-tetraene fragments, and three boratacyclobutane fragments. The dipole moment μ(Yb@C60) is directed from the cavity center to Yb; the dipole moment μ(Gd@η6-B3C57) is greater and has the opposite direction (from B3 to Gd). The populations of the 4f-shells of the Yb and Gd atoms are conserved. The binding energy of the endoatom in Ln@BkC60–k is significantly higher than that in Yb@C60.