Regiospecific Addition of La@C82 with Alkylidene, Alkyl Radical and Carbanion: Prediction of Regioisomers by Using "Paired Interacting Orbitals" (PIO) Analysis

Akinobu SHIGAa*, Midori O. ISHITSUKAb and Takeshi AKASAKAb

aLUMMOX Labo.Takezono
2-18-4-302, Tsukuba, Ibaraki 305-0032, Japan
bCenter for Tsukuba Advanced Research Alliance, Univ. of Tsukuba
Ibaraki 305-8577, Japan

(Received: April 23, 2009; Accepted for publication: July 7, 2009; Advance publication: August 25, 2009)

  Endohedral metallofullerenes (EMFs) are expected to have a wide range of potential applications in nanomaterials science. Chemical modification of EMFs is very important for their applications. La@C82 possesses 24 non-equivalent carbon atoms. Regioselectivies of reactions of La@C82 is a specially important problem. We applied the Paired Interacting Obitals (PIO) analysis for addition of adamantylidene(Ad), methyl anion(CH3-), diethyl bromomalonate anion(DBEM-) and methyl radical(.CH3) to La@C82. PIO calculation, proposed by Fujimoto et al., is a method for unequivocally determining the orbitals which should play dominant roles in chemical interactions between two systems, here, La@C82 and each of the above reagents. Eigen values of PIOs, which mean the contribution of PIOs, tell us that the interaction between the reagent and the La@C82 is mainly expressed in only one PIO, PIO-1, in each addition. Considering simultaneously the overlap population(OP) of the PIO-1 and the localization ratio of the PIO-1 of each atom, the most reactive carbons are the carbon(7) in Ad addition, the carbon(23) in DBEM- addition and carbon(9) or carbon(10) in .CH3 addition, respectively,. These results are coincident with the experimental results. A combination of OP and the localization ratio of the PIO-1 is a good reactivity index of each regioselective addition.

キーワード: La@C82, Alkyl, Alkylidene, Addition, PIO

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