Theoretical studies on the BN substituted fullerenes C70-2x(BN)(x) (x=1-3)- isoelectronic equivalents of C-70

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 mo st stable isomers of C70-2x(BN)x have been found out and their electronic p roperties have been predicted. The calculation results show that the BN sub stituted fullerenes C70-2x(BN)(x) have considerable stabilities, though the y are less stable than their all carbon analog. For C68BN, the isomers whos e 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 grou nd 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; F or 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 almo st the same as those of C-70 because of the isoelectronic relationship. The ionization potentials and affinity energies depend on the relative positio n of the heteroatoms in C68BN, the chemical reactivities of the isomers who se heteroatoms are well separated should differ significantly from their al l carbon analog. (C) 1999 Elsevier Science B.V. All rights reserved.