Exceptional Chemical Properties of Sc@<i>C</i>_2<i>v</i>(9)–C₈₂ Probed with Adamantylidene Carbene

It has been an interesting finding that reactions of M@<i>C</i>_2<i>v</i>(9)–C₈₂ (M = Y, La, Ce, Gd) with diazirine adamantylidene (AdN₂, <b>1</b>) gave rise to only two monoadduct isomers, indicating that the cage reactivity of monometallofullerenes is not dependent on the type of the internal metal. However, we found here that Sc@<i>C</i>_2<i>v</i>(9)–C₈₂ shows an exceptional chemical reactivity toward the electrophile <b>1</b>, affording four monoadduct isomers (<b>2a</b>–<b>d</b>). Single-crystal X-ray diffraction crystallographic results of the most abundant isomer (<b>2a</b>) confirm that the addition takes place at a [6,6]-bond junction which is very close to the internal metal ion. Theoretical calculations reveal that 2 out of the 24 nonequivalent cage carbons of Sc@<i>C</i>_2<i>v</i>(9)–C₈₂ are highly reactive toward <b>1</b>, but only one cage carbon of the other M@<i>C</i>_2<i>v</i>–C₈₂ (M = Y, La, Ce, Gd) is sufficiently reactive. The exceptional chemical property of Sc@<i>C</i>_2<i>v</i>(9)–C₈₂ is associated with the small ionic radius of Sc³⁺, which allows stronger metal–cage interactions and makes back-donation of charge from the cage to the metal more pronounced. Our results have provided new insights into the art of altering the chemical properties of fullerene molecules at the atomic level, which would be useful in the future in utilizing EMFs in quantum computing systems

Exceptional Chemical Properties of Sc@<i>C</i>_2<i>v</i>(9)–C₈₂ Probed with Adamantylidene Carbene

It has been an interesting finding that reactions of M@<i>C</i>_2<i>v</i>(9)–C₈₂ (M = Y, La, Ce, Gd) with diazirine adamantylidene (AdN₂, <b>1</b>) gave rise to only two monoadduct isomers, indicating that the cage reactivity of monometallofullerenes is not dependent on the type of the internal metal. However, we found here that Sc@<i>C</i>_2<i>v</i>(9)–C₈₂ shows an exceptional chemical reactivity toward the electrophile <b>1</b>, affording four monoadduct isomers (<b>2a</b>–<b>d</b>). Single-crystal X-ray diffraction crystallographic results of the most abundant isomer (<b>2a</b>) confirm that the addition takes place at a [6,6]-bond junction which is very close to the internal metal ion. Theoretical calculations reveal that 2 out of the 24 nonequivalent cage carbons of Sc@<i>C</i>_2<i>v</i>(9)–C₈₂ are highly reactive toward <b>1</b>, but only one cage carbon of the other M@<i>C</i>_2<i>v</i>–C₈₂ (M = Y, La, Ce, Gd) is sufficiently reactive. The exceptional chemical property of Sc@<i>C</i>_2<i>v</i>(9)–C₈₂ is associated with the small ionic radius of Sc³⁺, which allows stronger metal–cage interactions and makes back-donation of charge from the cage to the metal more pronounced. Our results have provided new insights into the art of altering the chemical properties of fullerene molecules at the atomic level, which would be useful in the future in utilizing EMFs in quantum computing systems

The enunciation of 'terrorism' as a kind of power and its distribution in the West

This paper is motivated by the assumption that ‘terrorism’ is a loaded and politically significant term, the use of which exudes and produces power relations. It acknowledges this, and also argues that not everyone has an equal right to use the term. This leads to an examination into the kind of power that is manifested in the use of the term, by putting the social constructivist framework to work and placing the semantic field of terrorism within that framework. It identifies a kind of power attached to the enunciation of the term ‘terrorism’ and argues that it is unequally distributed between perceived potential victims of terrorism and perceived potential perpetrators of terrorism. Drawing on Nietzsche’s genealogical analysis of morality, I argue that it is counterproductive to deny potential perpetrators the power of enunciation around the term ‘terrorism’ on the basis that this leads to a kind of slave revolt in terrorism. Redistributing the power of enunciation around the term ‘terrorism’ might remove the line that separates potential victims from potential perpetrators of terrorism and work towards reducing the threat of terrorism itself by allowing those potential perpetrators to exercise this capability within mainstream society, as opposed to seeking alternative communities to do so outside of it

Chemical Understanding of Carbide Cluster Metallofullerenes: A Case Study on Sc₂C₂@<i>C</i>_2<i>v</i>(5)–C₈₀ with Complete X-ray Crystallographic Characterizations

Little is known about the chemical properties of carbide cluster metallofullerenes (CCMFs). Here we report the photochemical reaction of a newly assigned CCMF Sc₂C₂@<i>C</i>_2<i>v</i>(5)–C₈₀ with 2-adamantane-2,3-[3<i>H</i>]-diazirine (AdN₂, <b>1</b>), which provides a carbene reagent under irradiation. Five monoadduct isomers (<b>2a</b>–<b>2e</b>), with respective abundances of 20%, 40%, 25%, 5%, and 10%, were isolated and characterized with a combination of experimental techniques including unambiguous single-crystal X-ray crystallography. Results show that the two Sc atoms of the bent Sc₂C₂ cluster tend to move in most cases, whereas the C₂-unit is almost fixed. Accordingly, it is difficult to explain the addition patterns by considering the strain and charge density on the cage with a fixed cluster, and thus a moving cluster may account for the addition patterns. These results show that the situation of CCMFs is more complicated than those in other metallofullerenes. Furthermore, a thermal isomerization process from <b>2b</b> to <b>2c</b> was observed, confirming that the most abundant isomer <b>2b</b> is a kinetically favored adduct. Finally, it is revealed that the electronic and electrochemical properties of pristine Sc₂C₂@<i>C</i>_2<i>v</i>(5)–C₈₀ have been markedly altered by exohedral modification

Chemical Understanding of Carbide Cluster Metallofullerenes: A Case Study on Sc₂C₂@<i>C</i>_2<i>v</i>(5)–C₈₀ with Complete X-ray Crystallographic Characterizations

Little is known about the chemical properties of carbide cluster metallofullerenes (CCMFs). Here we report the photochemical reaction of a newly assigned CCMF Sc₂C₂@<i>C</i>_2<i>v</i>(5)–C₈₀ with 2-adamantane-2,3-[3<i>H</i>]-diazirine (AdN₂, <b>1</b>), which provides a carbene reagent under irradiation. Five monoadduct isomers (<b>2a</b>–<b>2e</b>), with respective abundances of 20%, 40%, 25%, 5%, and 10%, were isolated and characterized with a combination of experimental techniques including unambiguous single-crystal X-ray crystallography. Results show that the two Sc atoms of the bent Sc₂C₂ cluster tend to move in most cases, whereas the C₂-unit is almost fixed. Accordingly, it is difficult to explain the addition patterns by considering the strain and charge density on the cage with a fixed cluster, and thus a moving cluster may account for the addition patterns. These results show that the situation of CCMFs is more complicated than those in other metallofullerenes. Furthermore, a thermal isomerization process from <b>2b</b> to <b>2c</b> was observed, confirming that the most abundant isomer <b>2b</b> is a kinetically favored adduct. Finally, it is revealed that the electronic and electrochemical properties of pristine Sc₂C₂@<i>C</i>_2<i>v</i>(5)–C₈₀ have been markedly altered by exohedral modification

Where Does the Metal Cation Stay in Gd@<i>C</i>_2<i>v</i>(9)-C₈₂? A Single-Crystal X-ray Diffraction Study

Metal positions in endohedral metallofullerenes (EMFs) are of special importance because their molecular symmetry and intrinsic properties are strongly influenced by the location and motion of the encapsulated metals. X-ray analyses of the cocrystals of Gd@<i>C</i>_2<i>v</i>(9)-C₈₂ with nickel^II octaethylporphyrin [Ni^II(OEP)] reveal that the Gd³⁺ cation is off-center, being located under a hexagonal ring along the 2-fold axis of the <i>C</i>_2<i>v</i>(9)-C₈₂ cage. This result is in sharp contrast to that of a previous study, showing that Gd@<i>C</i>_2<i>v</i>(9)-C₈₂ has an anomalous endohedral structure, with the metal being positioned over a [6,6] bond, which is opposite to the hexagonal ring along the C₂ axis (<i>Phys. Rev. B</i> <b>2004</b>, <i>69</i>, 113412). In agreement with theoretical calculations and related studies, it is conclusive that the single rare-earth metal in M@<i>C</i>_2<i>v</i>(9)-C₈₂ always tends to coordinate with the hexagonal ring along the 2-fold axis, instead of interacting with the [6,6] bond on the other end, regardless of the type of metal atom

Where Does the Metal Cation Stay in Gd@<i>C</i>_2<i>v</i>(9)-C₈₂? A Single-Crystal X-ray Diffraction Study

Metal positions in endohedral metallofullerenes (EMFs) are of special importance because their molecular symmetry and intrinsic properties are strongly influenced by the location and motion of the encapsulated metals. X-ray analyses of the cocrystals of Gd@<i>C</i>_2<i>v</i>(9)-C₈₂ with nickel^II octaethylporphyrin [Ni^II(OEP)] reveal that the Gd³⁺ cation is off-center, being located under a hexagonal ring along the 2-fold axis of the <i>C</i>_2<i>v</i>(9)-C₈₂ cage. This result is in sharp contrast to that of a previous study, showing that Gd@<i>C</i>_2<i>v</i>(9)-C₈₂ has an anomalous endohedral structure, with the metal being positioned over a [6,6] bond, which is opposite to the hexagonal ring along the C₂ axis (<i>Phys. Rev. B</i> <b>2004</b>, <i>69</i>, 113412). In agreement with theoretical calculations and related studies, it is conclusive that the single rare-earth metal in M@<i>C</i>_2<i>v</i>(9)-C₈₂ always tends to coordinate with the hexagonal ring along the 2-fold axis, instead of interacting with the [6,6] bond on the other end, regardless of the type of metal atom

Chemical Understanding of Carbide Cluster Metallofullerenes: A Case Study on Sc₂C₂@<i>C</i>_2<i>v</i>(5)–C₈₀ with Complete X-ray Crystallographic Characterizations

Little is known about the chemical properties of carbide cluster metallofullerenes (CCMFs). Here we report the photochemical reaction of a newly assigned CCMF Sc₂C₂@<i>C</i>_2<i>v</i>(5)–C₈₀ with 2-adamantane-2,3-[3<i>H</i>]-diazirine (AdN₂, <b>1</b>), which provides a carbene reagent under irradiation. Five monoadduct isomers (<b>2a</b>–<b>2e</b>), with respective abundances of 20%, 40%, 25%, 5%, and 10%, were isolated and characterized with a combination of experimental techniques including unambiguous single-crystal X-ray crystallography. Results show that the two Sc atoms of the bent Sc₂C₂ cluster tend to move in most cases, whereas the C₂-unit is almost fixed. Accordingly, it is difficult to explain the addition patterns by considering the strain and charge density on the cage with a fixed cluster, and thus a moving cluster may account for the addition patterns. These results show that the situation of CCMFs is more complicated than those in other metallofullerenes. Furthermore, a thermal isomerization process from <b>2b</b> to <b>2c</b> was observed, confirming that the most abundant isomer <b>2b</b> is a kinetically favored adduct. Finally, it is revealed that the electronic and electrochemical properties of pristine Sc₂C₂@<i>C</i>_2<i>v</i>(5)–C₈₀ have been markedly altered by exohedral modification

X-ray Structures of Sc₂C₂@C_2<i>n</i> (<i>n</i> = 40–42): In-Depth Understanding of the Core–Shell Interplay in Carbide Cluster Metallofullerenes

X-ray analyses of the cocrystals of a series of carbide cluster metallofullerenes Sc₂C₂@C_2<i>n</i> (<i>n</i> = 40–42) with cobalt­(II) octaethylporphyrin present new insights into the molecular structures and cluster–cage interactions of these less-explored species. Along with the unambiguous identification of the cage structures for the three isomers of Sc₂C₂@<i>C</i>_2<i>v</i>(5)-C₈₀, Sc₂C₂@<i>C</i>_3<i>v</i>(8)-C₈₂, and Sc₂C₂@<i>D</i>_2<i>d</i>(23)-C₈₄, a clear correlation between the cluster strain and cage size is observed in this series: Sc–Sc distances and dihedral angles of the bent cluster increase along with cage expansion, indicating that the bending strain within the cluster makes it pursue a planar structure to the greatest degree possible. However, the C–C distances within Sc₂C₂ remain unchanged when the cage expands, perhaps because of the unusual bent structure of the cluster, preventing contact between the cage and the C₂ unit. Moreover, analyses revealed that larger cages provide more space for the cluster to rotate. The preferential formation of cluster endohedral metallofullerenes for scandium might be associated with its small ionic radius and the strong coordination ability as well

X-ray Structures of Sc₂C₂@C_2<i>n</i> (<i>n</i> = 40–42): In-Depth Understanding of the Core–Shell Interplay in Carbide Cluster Metallofullerenes

X-ray analyses of the cocrystals of a series of carbide cluster metallofullerenes Sc₂C₂@C_2<i>n</i> (<i>n</i> = 40–42) with cobalt­(II) octaethylporphyrin present new insights into the molecular structures and cluster–cage interactions of these less-explored species. Along with the unambiguous identification of the cage structures for the three isomers of Sc₂C₂@<i>C</i>_2<i>v</i>(5)-C₈₀, Sc₂C₂@<i>C</i>_3<i>v</i>(8)-C₈₂, and Sc₂C₂@<i>D</i>_2<i>d</i>(23)-C₈₄, a clear correlation between the cluster strain and cage size is observed in this series: Sc–Sc distances and dihedral angles of the bent cluster increase along with cage expansion, indicating that the bending strain within the cluster makes it pursue a planar structure to the greatest degree possible. However, the C–C distances within Sc₂C₂ remain unchanged when the cage expands, perhaps because of the unusual bent structure of the cluster, preventing contact between the cage and the C₂ unit. Moreover, analyses revealed that larger cages provide more space for the cluster to rotate. The preferential formation of cluster endohedral metallofullerenes for scandium might be associated with its small ionic radius and the strong coordination ability as well