Unexpected formation of 1,2- and 1,4-bismethoxyl Sc(3)N@I(h)-C(80) derivatives via regioselective anion addition: an unambiguous structural identification and mechanism study

An attempt to achieve heterocyclic cycloadducts of Sc(3)N@I(h)-C(80)via reaction with Ph(2)C[double bond, length as m-dash]O, PhC[triple bond, length as m-dash]CPh or PhC[triple bond, length as m-dash]N in the presence of tetrabutylammonium hydroxide (TBAOH) stored in CH(3)OH led to the formation of the unexpected bismethoxyl adducts of Sc(3)N@I(h)-C(80) (1 and 2). Further studies reveal that TBAOH in CH(3)OH can boost the CH(3)O(−) addition efficiently, regardless of the presence of other reagents. Single-crystal X-ray diffraction results firmly assign the molecular structures of 1 and 2 as respective 1,4- and 1,2-bismethoxyl adducts, and reveal unusual relationships between the internal Sc(3)N cluster and the addition modes, in addition to the unusual packing mode in view of the orientation of the methoxyl groups. Electrochemical results demonstrate smaller electrochemical gaps for 1 and 2, relative to that of Sc(3)N@I(h)-C(80), confirming their better electroactive properties. Finally, a plausible reaction mechanism involving anion addition and a radical reaction was proposed, presenting new insights into the highly selective reactions between the methoxyl anion and metallofullerenes. 1 and 2 represent the first examples of methoxyl derivatives of metallofullerenes. This work not only presents a novel and facile strategy for the controllable synthesis of alkoxylated metallofullerene derivatives, but also provides new non-cycloadducts for the potential applications of EMFs.