ELECTRONIC-STRUCTURES OF 1,2-C60X2N AND 1,4-C60X2N DERIVATIVES WITH N = 1, 2, 4, 6, 8, 10, 12, 18, 24, AND 30

Addition to C60 has been predicted to occur at the 1,2- and 1,4-positions of a cyclohexatriene moiety. The geometric and electronic structures of 1,2- and 1,4-C60X2n's (X = H, F, Cl, Br and I; n = 1, 2, 4, 6, 8, 10, 12, 18, 24, and 30) were calculated with the semiempirical MNDO/AM1 method. The calculated geometries for the 1,2-C60X2n'S show that for 12 greater-than-or-equal-to n greater-than-or-equal-to 6, nonbonded interactions due to addition to neighboring double bonds lead to destabilized structures. The effect of these interactions on the geometry is limited to the local area where addition occurs. For n > 12, the nonbonded interactions lead to deformation of the C60 framework. For C60X60, a simple geometrical model shows that all such structures will have significant steric interactions leading to destabilization. The differences in 1,2- and 1,4-addition are also discussed as a function of n.