Adamantylidene Addition to M3N@Ih-C80 (M=Sc, Lu) and Sc3N@D5h-C80: Synthesis and Crystallographic Characterization of the [5,6]-Open and [6,6]-Open Adducts
Abstract
Additions of adamantylidene (Ad) to M3N@I(h)-C-80 (M=Sc, Lu) and Sc3N@D(5h)-C-80 have been accomplished by photochemical reactions with 2-adamantyl-2,3-[3H]-diazirine (1). In M3N@I(h)-C-80, the addition led to rupture of the [6,6]- or [5,6]-bonds of the I(h)-C-80 cage, forming the [6,6]-open fulleroid as the major isomer and the [5,6]-open fulleroid as the minor isomer.
In Sc3N@D(5h)-C-80, the addition also proceeded regioselectively to yield three major isomeric Ad mono-adducts, despite the fact that there are nine types of C-C bonds in the D(5h)-C-80 cage. The molecular structures of the seven Ad mono-adducts, including the positions of the encaged trimetallic nitride clusters, have been unambiguously determined through single-crystal XRD analyses.
Furthermore, results have shown that stepwise addition of Ad to Lu3N@I(h)-C-80 affords several Ad bis-adducts, two of which have been isolated and characterized. The X-ray structure of one bis-adduct clearly revealed that the second Ad addition took place at a [6,6]-bond close to an endohedral metal atom.
Theoretical calculations have also been performed to rationalize the regioselectivity.