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

摘要

The equilibrium structures and relative stabilities of BN-doped fullerenes C_(70-2x)(BN)_x (x = 1 - 3) have studied at the AM1 and MNDO level. The most stable isomers of C_(70-2x)(BN)_x have been found out and their electronic properties have been predicted. The calculation results show that the BN substituted fullerenes C_(70 - 2x)(BN)_x have considerable stabilities, though they are less stable than their all carbon analog. For C_(68)BN, 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 C_(68)BN 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 C_(68)BN, the chemical reactivities of the isomers whose heteroatoms are well separated should differ significantly from their all carbon analog.