Structures and magnetic properties of mono-doped fullerenes C59Xn and C59X(6-n)- (X = B-, N+, P+, As+, Si):: isoelectronic analogues of C60 and C606-

Structures of mono-doped fullerenes, C59Xn and C59X(6-n)- (X=B-, N+, P+, As+, Si), the isoelectronic analogues to C-60 and C-60(6-) with 60 and 66 pi-electrons, have been investigated at the B3LYP/6-31G* level of density functional theory. On the basis of the computed nucleus independent chemical shifts (NICS) at the cage center and also at the center of individual rings as magnetic criteria, heterofullerenes with 60 pi-electrons are as aromatic as the parent C-60, while those with 66 pi-electrons are much less aromatic than C-60(6-). The very distinct endohedral chemical shifts of the 66 pi-electron systems may be useful to identify the heterofullerenes through their endohedral He-3 NMR chemical shifts.