Highly Regioselective Derivatization Of Trimetallic Nitridetemplated Endohedral Metallofullerenes Via A Facilernphotochemical Reaction

摘要

Photochemically generated benzyl radicals react with Sc_3N@C_(80)-I_h to produce a dibenzyl adduct [Sc_3N@C_(80)(CH_2C_6H_5)_2] in 82% yield and high regioselectivity. The adduct's ~1H spectrum revealed high symmetry: only one AB pattern was observed for the methylene protons. The ~(13)C NMR spectrum suggested a C_2-symmetrical structure. DFT calculations reveal that a 1,4-adduct is more favorable than a 1,2-adduct by >10 kcal/mol. The 1,4-structure on [566] ring junctions was unambiguously confirmed by X-ray crystallographic analysis. UV-vis spectra revealed that the removal of two p orbitals from the π system of the cage together with the benzylic substituents change the electronic properties of the metallofullerene in a manner similar to those reported for disilirane and trifluoromethyl moieties. Under the same conditions from Lu_3N@C_(80)-I_h we prepared (63% yield) Lu_3N@C_(80)(CH_2C_6H_5)_2, which demonstrated properties similar to the 1,4-dibenzyl adduct of Sc_3N@C_(80)-I_h.