Abstract: Using INDO series of methods, we have performed the theoretical studies on the structure of the intermediate C₆₀(CH₃)^-resulting from the reaction between C₆₀^2-and CH₃, and obtained the Cs geometry. It is indicated from the studies that the net charge and spin density on the atom C₃₀which is adjacent to C₁₅and locates on the double bond reach the maxima when CH₃is added to C₁₅, and thus the most reactive site is on C₃₀when C₆₀(CH₃)^-reacts with second CH₃ In addition, the opposite location of C₁₆ that is C₁₂or C₂₇is easier to react than any other one except for C₃₀, moreover there are double location in this way;therefore the product C₆₀(CH₃)₂may be the mixture of the two isomers which are products of 1,2-addition and 1,4-addition on the six-membered ring. In the paper,we have made the theoretical exploration on the structure and the electronic spectrum of the product C₆₀(CH₃)₂and assigned the partial electronic transition, meanwhile discussed the reason about the redshift of its spectrum compared with C₆₀.

Key words: C₆₀(CH₃)^-, C₆₀(CH₃)₂, INDO,Electronic spectrum