Hydro‐aza‐(C₅₉N)fullerenes: Formation Mechanism and Hydrogen Substitution

Abstract

Azafullerenes are as yet the only synthetically available heterofullerenes. Herein, we present plausible reaction pathways towards pentaaryl azafullerenes, focusing on the reactivity of hydro-azafullerene intermediates and their regiochemistry. The X-ray structure of a β'-hydro-tetraaryl adduct is presented for the first time. The reactivity of dihydro-azafullerene adducts is demonstrated here through H-abstraction in mass spectrometric experiments. Moreover, hydride abstraction and subsequent hydroxylation is possible, as well as deprotonation followed by alkylation.

Synthesis, Structural Characterization, and Crystal Packing of the Elusive Pentachlorinated Azafullerene C59NCl5

“…A similar pentaaddition pattern was observed upon multiple trifluoromethyl radical additions to (C 59 N) 2 . Recently, several pentaadducts of C 59 N with various combination of hydrogen‐ and aryl addends were synthesized by electrophilic aromatic substitution reactions and were unambiguously characterized by means of single crystal X‐ray analysis . A very interesting aspect of such pentaaddition patterns is that the corresponding derivatives tend to adopt columnar stacking motifs in the solid state by nestling the ball‐shaped subunit into the cavity formed by five addends of an adjacent molecule .…”

“…Upon bromine addition to the solution of (C 59 N) 2 in anhydrous o ‐DCB (Figure ), the colour of the reaction mixture changed immediately from green to orange, which is typical for the C 59 N pentaadducts. The absorption spectrum was found to be similar to that previously reported for C 59 NArCl 4 and pentaarylated adducts (see the Supporting Information). The addition pattern that agrees with the spectroscopic data features an integral pyrrole moiety in the fullerene core.…”

“…[6] Recently,s everalp entaadducts of C 59 Nw ith various combination of hydrogen-and aryl addends were synthesized by electrophilic aromatics ubstitution reactions and were unambiguously characterizedb ym eans of single crystal X-ray analysis. [7,8] Av ery interesting aspect of such pentaaddition patterns is that the corresponding derivatives tend to adopt columnar stacking motifs in the solid state by nestling the ballshaped subunit into the cavity formed by five addends of an adjacent molecule. [6] Although chlorination is one of the first reactions in azafullerene chemistry, [5] the pentachloride C 59 NCl 5 ( Figure 1) remains elusive.…”

Solution-phase molecular recognition of an azafullerene-quinoline dyad by a face-to-face porphyrin-dimer tweezer

“…Apart from the mono-adducts, C 59 N has also a rich chemistry towards multi-addition patterns. [12][13][14][15][16][17] Notably, we recently reported the tether-directed regioselective synthesis of an equatorial-face bis-adduct of C 59 N, as single isomer, based on a two-step mono-addition reaction sequence employing cyclo- [2]-octylmalonate. 18 In contrast, the supramolecular chemistry of C 59 N is less explored.…”

Tether‐Directed Regioselective Synthesis of an Equatorialface Bisadduct of Azafullerene Using Cyclo‐[2]‐octylmalonate

“…A similar penta‐addition pattern (Figure b) was obtained by addition of trifluoromethyl radicals to (C 59 N) 2 , and the pentachloride C 59 NCl 5 was synthesized by high‐temperature chlorination of (C 59 N) 2 . Furthermore, electrophilic aromatic substitution reactions have been successfully employed for the synthesis of penta‐adducts of C 59 N bearing aryl addends with the same penta‐addition pattern, akin to C 60 adducts with an isolated cyclopentadiene substructure within the fullerene framework . Finally, multiple functionalization of azafullerene derivatives RC 59 N with diethyl bromomalonate in the presence of dimethylanthracene afforded C s ‐symmetrical pentakis‐adducts with an octahedral arrangement of the malonate addends (Figure c) …”