A crystalline anionic complex of scandium nitride endometallofullerene: experimental observation of single-bonded (Sc₃N@I_h-C₈₀⁻)₂ dimers

Abstract

Reduction of scandium nitride clusterfullerene, Sc3N@Ih-C80, by sodium fluorenone ketyl in the presence of cryptand[2,2,2] allows the crystallization of the {cryptand[2,2,2](Na+)}2(Sc3N@Ih-C80−)2·2.5C6H4Cl2 (1) salt. The Sc3N@Ih-C80•− radical anions are dimerized to form single-bonded (Sc3N@Ih-C80−)2 dimers.

Dimerization of Endohedral Fullerene in a Superatomic Crystal

“…THJ–THJ, PHHJ–PHHJ and THJ–PHHJ dimers shown in Figure ) to understand why, unlike what has been reported for [(Sc 3 N@C 80 ) 2 ] 2− , the [(Lu 3 N@C 80 ) 2 ] 2− dimer forms exclusively through the THJ junctions. As previously pointed out by Konarev and Popov, the energy differences between the THJ, PHHJ, and mixed THJ–PHHJ for the [(Sc 3 N@C 80 ) 2 ] 2− dimers computed with the PBE functional and using a continuum model solvent are small . At an analogous computational level, similar results are obtained for [(Lu 3 N@C 80 ) 2 ] 2− : the three dimers are found within a range of only 1.1 kcal mol −1 , (see Figure and Table S2).…”

“…The triangular planar Lu 3 N clusters inside the dimerized C 80 cages are coplanar and collinear with the bridging C−C single bond, and point at each other. This observation contrasts with theoretical calculations and a recent experimental report of [(Sc 3 N@C 80 ) 2 ] 2− dimers in which the clusters point away from each other . To understand this unusual orientation, we complement our experimental results with density functional theory (DFT) calculations.…”

“…Single‐bonded dimers have been observed for reduced C 60 and C 70 , and suggested both theoretically and spectroscopically for endohedral fullerenes. Konarev and co‐workers recently reported the first crystallographic evidence of dimerization of [Sc 3 N@C 80 ] − upon reduction with sodium fluorenone ketyl . The Sc 3 N@C 80 dimer structure features significant disorder of the cages, the inter‐cage C−C bond and the cluster but the orientation of the Sc 3 N cluster with respect to the inter‐cage C−C bond is clear and in agreement with theory: the triangular planar Sc 3 N clusters are close to collinear with the bridging C−C single bond, and point away from each other.…”

“…The fully ordered structure for the [(Lu 3 N@C 80 ) 2 ] 2− dimer differs significantly from that of [(Sc 3 N@C 80 ) 2 ] 2− . While the inter‐cage C−C bond length (1.66(6) Å) for [(Lu 3 N@C 80 ) 2 ] 2− is comparable to that for [(Sc 3 N@C 80 ) 2 ] 2− , it selectively links the hexagon‐hexagon‐hexagon junctions (THJ) of neighboring C 80 cages (Figure d).…”

Structure of [60]fullerene with a mobile lithium cation inside

“…A crystal of dimerized Li + @C 60 − without anions was also obtained by electrochemical reduction [22]. The crystal is different from other dimerized endohedral metallofullerene crystals that consist of negatively charged endohedral metallofullerenes and positively charged donor molecules [23,24]. The Li + cation in the dimerized Li + @C 60 − is localized near the carbon atom that is nearest to the carbon atom forming an inter-fullerene single C–C bond at 100 K. Temperature dependence of the position and motion of the localized Li + cation in the dimerized Li + @C 60 − would provide us with essential information about the thermal stability of the (Li + @C 60 − ) 2 dimer and the Li + –C bond.…”