Connectivity of the Chiral D₂‐Symmetric Isomer of C₇₆ through a Crystal‐Structure Determination of C₇₆Cl₁₈⋅TiCl₄

Abstract

Ein chirales Fulleren: Die erste geordnete Kristallstruktur eines Derivats des D2‐symmetrischen C76‐Fullerens, C76Cl18, wurde bestimmt. Das verzerrte Kohlenstoffgerüst von C76Cl18 enthält verlängerte C‐C‐Bindungen und ein in dieser Form einzigartiges π‐System. Der C76‐Käfig (siehe Bild; grün) ist durch zwei helicale Gürtel von Chloratomen umgeben (orange).

C80Cl12: A Chlorine Derivative of the Chiral D2‐C80 Isomer—Empirical Rationale of Halogen‐Atom Addition Pattern

“…The tendency of generating ribbons of 1,4-addition exclusively was first reported by Strauss et al, [10] proposing by this a principle of higher fullerene reactivity. However, the violation of this principle in the case of C 76 Cl 18 in which ten out of eighteen chlorine atoms bind to ICCB carbon atoms, thus at 1,2-positions in hexagons, [5] needs to be discussed.…”

“…[1] Two of them, D 5d -C 80 (1) and D 2 -C 80 (2) (fullerene nomenclature according to reference [1]), have been found in fullerene extracts and isolated by means of HPLC techniques. [2,3] Recently, a third representative of the family, C 2v -C 80 (5), was identified and its constitution pattern confirmed by 19 3 ) 12 . [4] Although the relative abundance of C 80 (2) to C 80 (1) of about 30:1, [2] as well as the simple isolation procedure for C 80 (2), provide ground for investigating the chemical reactivity of this species, no exohedral derivative of it has ever been synthesized.…”

“…Probing the reactivity of this isomer appears particularly worthwhile when taking into consideration that it represents another chiral fullerene after D 2 -C 76 (1), the constitution pattern of which has recently been confirmed through its chlorine derivative C 76 Cl 18 . [5] Herein we report the synthesis and single-crystal structure analysis of C 80 Cl 12 , the first exohedral derivative of C 80 (2). The synthetic method, employing a mixture of TiCl 4 and Br 2 , is adopted from the procedure used for chlorinating C 76 (1), which has proven highly selective resulting in wellcrystallized enantiomorphs of C 76 (1).…”

“…The synthetic method, employing a mixture of TiCl 4 and Br 2 , is adopted from the procedure used for chlorinating C 76 (1), which has proven highly selective resulting in wellcrystallized enantiomorphs of C 76 (1). [5] The quality of C 80 Cl 12 crystals has allowed structure determination of high accuracy, presenting all atoms in ordered and fixed positions (Figure 1). [6] The solvent-free crystals of C 80 Cl 12 consist of the two enantiomers of this fullerene species with the connectivity pattern of carbon atoms preserved as suggested for the pristine C 80 (2) enantiomorphs.…”

Chlorinated Derivatives of C78‐Fullerene Isomers with Unusually Short Intermolecular Halogen–Halogen Contacts

“…[3] The next recoverable from soot fullerene, C 78 , has five IPR isomers. [4] Although separation techniques applicable to the soluble C 78 isomers (C 78 (1), C 78 (2), and C 78 (3)) are commonly available, [5,6] only two crystal structures including soluble C 78 isomers as halogenated derivatives were reported thus far. [7] However, in these cases, different structural isomers occupy the fullerene site, which are presumably C 78 (2) and C 78 (3).…”