Sc₂S@C_s(10528)-C₇₂: A Dimetallic Sulfide Endohedral Fullerene with a Non Isolated Pentagon Rule Cage

Abstract

A non isolated pentagon rule metallic sulfide clusterfullerene, Sc(2)S@C(s)(10528)-C(72), has been isolated from a raw mixture of Sc(2)S@C(2n) (n = 35-50) obtained by arc-discharging graphite rods packed with Sc(2)O(3) and graphite powder under an atmosphere of SO(2) and helium. Multistage HPLC methods were utilized to isolate and purify the Sc(2)S@C(72). The purified Sc(2)S@C(s)(10528)-C(72) was characterized by mass spectrometry, UV-vis-NIR absorption spectroscopy, cyclic voltammetry, and single-crystal X-ray diffraction. The crystallographic analysis unambiguously elucidated that the C(72) fullerene cage violates the isolated pentagon rule, and the cage symmetry was assigned to C(s)(10528)-C(72). The electrochemical behavior of Sc(2)S@C(s)(10528)-C(72) shows a major difference from those of Sc(2)S@C(s)(6)-C(82) and Sc(2)S@C(3v)(8)-C(82) as well as the other metallic clusterfullerenes. Computational studies show that the Sc(2)S cluster transfers four electrons to the C(72) cage and C(s)(10528)-C(72) is the most stable cage isomer for both empty C(72)(4-) and Sc(2)S@C(72), among the many possibilities. The structural differences between the reported fullerenes with C(72) cages are discussed, and it is concluded that both the transfer of four electrons to the cage and the geometrical requirements of the encaged Sc(2)S cluster play important roles in the stabilization of the C(s)(10528)-C(72) cage.

Mononuclear Clusterfullerene Single‐Molecule Magnet Containing Strained Fused‐Pentagons Stabilized by a Nearly Linear Metal Cyanide Cluster

“…Among them, the major metal site has an occupancy of 0.689(3) and 0.871(2) for Tb and Y, respectively, which locates just under the junction of the fused‐pentagon (see Figure 1 c,f). This is quite similar to the reported non‐IPR clusterfullerenes such as Sc 3 N@ D 3 (6140)‐C 68 6b and Sc 2 S@ C s (10528)‐C 72 6g. Thus, it is the strong coordination interaction between Tb/Y metal and the cage that stabilizes the fused‐pentagon within the non‐IPR C 2 v (19138)‐C 76 cage.…”

Sc2O@Td(19151)‐C76: Hindered Cluster Motion inside a Tetrahedral Carbon Cage Probed by Crystallographic and Computational Studies

“…The HOMO-LUMO gaps for these two endohedral fullerenes that share the same high-symmetry C 76 cage correlate with the experimental opticalb andgaps:0 .75 eV for Sc 2 O@T d (19151)-C 76 and 0.45 eV for Lu 2 @T d -C 76 .The computed UV/Vis/NIR spectrum from time-dependent DFTc alculations in the Vis/NIR region (wavelengths larger than 500 nm) shows reasonable agreement with the experimental one ( Figure S7 in the Supporting Information), despite the limitations of the methodology,a s found for the SCF family. [24,41] There are no UV/Vis/NIR data reported for other OCFs to be compared with, but the bandgap of Sc 2 O@T d (19151)-C 76 is smaller than all those of SCFs reported so far,i ncludingS c 2 S@C s (10528)-C 72 and two isomers of Sc 2 S@C 82 ,i nl ine with the computed HOMO-LUMO gaps. [24,25,41] We also carried out the first 45 Sc NMR spectroscopy studies on the OCF family.A sF igure 8s hows, as ingle line at d = 76.9 ppm was recorded in the 45 Sc NMR spectrumo fS c 2 O@C 76 .…”

“…[24,41] There are no UV/Vis/NIR data reported for other OCFs to be compared with, but the bandgap of Sc 2 O@T d (19151)-C 76 is smaller than all those of SCFs reported so far,i ncludingS c 2 S@C s (10528)-C 72 and two isomers of Sc 2 S@C 82 ,i nl ine with the computed HOMO-LUMO gaps. [24,25,41] We also carried out the first 45 Sc NMR spectroscopy studies on the OCF family.A sF igure 8s hows, as ingle line at d = 76.9 ppm was recorded in the 45 Sc NMR spectrumo fS c 2 O@C 76 . The single signal for 45 Sc suggests that the two Sc atoms in the Sc 2 Oc luster are essentially equivalent, which agreesw ith the significant rotation of the cluster at room temperature (see above)a nd the proposed highly symmetrical outside cage.…”

“…Therefore, the electronic structurec an be explained by the ionic model with af ormal transfer of four electrons from the clustert ot he cage, as for the rest of the cluster fullerenes containing Sc 2 X (X:Oor S) that are known so far. [21,24,25,41] We have also computed (BP86/TZP)t he energies of the tetra-anions for all cages with two or fewer adjacent pentagon pairs (APPs): 2I PR isomers, 12 APP1 isomers, and 134 APP2 isomers. The lowest-energy tetra-anionic cages, within ar ange of 40 kcal mol…”

“…[5][6][7][8][9] Since the discovery of Sc 3 N@C 80 in 1999, [10] cluster fullerenes (CFs) have been of particular interest in the field of endohedral fullerenes as ar esult of their exceptionally high yield and excellent stabilitya nd the unique structural variety of both clusters and cages, which resultsi nt heir tunable physical and chemical properties. [11][12][13][14] To date,avariety of cluster fullerenes have been reported, including nitride (NCFs), [15][16][17] carbide( CCFs), [18,19] hydrocarbide (HCCFs), [20] oxide (OCFs), [21,22] sulfide( SCFs), [23][24][25] carbonnitride (CNCFs), [26,27] and di/trimetallic clusterf ullerenes. [28,29] In particular,t he OCF family has demonstratede xceptional structuralv ersatility of the encapsulated oxide clusters, whichh ave includedS c 2 O, [21] Sc 4 O 2 , [22] and Sc 4 O 3 [30] structures.I ncontrast, the reported cage structures of this family have been limited to I h (7)-C 80 , C s (6)-C 82 ,a nd the very recent C 2 (7892)-C 70 cages.…”