Synthesis of Stable Derivatives of C₆₂:  The First Nonclassical Fullerene Incorporating a Four-Membered Ring

Abstract

A rational synthetic approach to the first four-membered ring-containing derivatives of C(62) is reported. They were synthesized by an inverse electron demand Diels-Alder reaction of 3,6-diaryl-1,2,4,5-tetrazines with C(60) in o-dichlorobenzene, followed by visible light irradiation at reflux. The structure of these nonclassical fullerenes derivatives was determined by X-ray single-crystal diffraction.

Novel Enhanced Sampling Strategies for Transitions Between Ordered and Disordered Structures

“…Among them, the zipping of a planar flake into a nanocone, the passage from a "bowl" to a cage with the help of carbon chains, and the formation of a pair of pentagons embedded into hexagons (the pyracylene unit, typical of fullerenes) by expelling a dimer from a four-membered ring. The latter transformation, in particular, is highly nontrivial, pointing to the exploration power of this technique, and is fully compatible with available experiments, being the inverse process of a well-known synthetic route to C 62 from the C 60 fullerene (Qian et al 2003).…”

Carbon polyhedrons formed by squares and hexagons obeying isolated square rule

“…But these polyhedrons can be stabilized via changing the carbon from sp 2 to sp 3 hybridization. Although few non-classical derivatives with square have been reported [28] , the considered F 4 F 6 polyhedrons and their derivatives are generally not favored in thermodynamics. Therefore, the F 4 F 6 polyhedrons of carbon and their derivatives are much more difficult to synthesize than classical fullerenes.…”

Six‐Membered Heterocycles: Triazines, Tetrazines and Other Polyaza Systems

“…Thermal Diels-Alder reactions between C 60 and electron-deficient 3,6-diaryl-1,2,4,5-tetrazines yielded monoadducts possessing a diaryldihydropyridazine function nested atop the fullerene [804]. However, when 3,6-diaryl-1,2,4,5-tetrazines and C 60 react upon irradiation with visible light, the four membered ring-containing C 62 derivatives were obtained [805]. 20.5.5.3 Reactions with Oxidizing Reagents 1,4-Dihydrotetrazines have been aromatized to tetrazines by exposure to nitrous gases [784].…”