Theoretical studies on the BN substituted fullerenes C70-2x(BN)x (x=1-3) -: isoelectronic equivalents of C70

The equilibrium structures and relative stabilities of BN-doped fullerenes C70-2x(BN)(x) (x = 1-3) have been studied at the AM1 and MNDO level. The most stable isomers of C70-2x(BN)x have been found out and their electronic properties have been predicted. The calculation results show that the BN substituted fullerenes C70-2x(BN)(x) have considerable stabilities, though they are less stable than their all carbon analog. For C68BN, the isomers whose BN is located in the most chemically active bonds of C-70 (namely B and A) are among the most stable species, of which B is predicted to be the ground state. The stabilities of C68BN decrease and the dipole moments increase with increasing the distance between the heteroatoms. For C-66(BN)(2), the lowest energy species is the isomer in which the B-N-B-N bond is formed; For C-64(BN)(3), the most stable species should have three BN units located in the same hexagon to form B-N-B-N-B-N ring. The ionization potentials and the affinity energies of the most stable species of BN-doped C-70 are almost the same as those of C-70 because of the isoelectronic relationship. The ionization potentials and affinity energies depend on the relative position of the heteroatoms in C68BN, the chemical reactivities of the isomers whose heteroatoms are well separated should differ significantly from their all carbon analog. (C) 1999 Elsevier Science B.V. All rights reserved.