Entrapped Bonded Hydrogen in a Fullerene: the Five‐Atom Cluster Sc₃CH in C₈₀

Abstract

The synthesis and characterisation of the new endohedral cluster fullerene Sc(3)CH@C(80) is reported. The encapsulation of the first hydrocarbon cluster inside a fullerene was achieved by the arc burning method in a reactive CH(4) atmosphere. The extensive characterisation by mass spectrometry (MS), high- pressure liquid chromatography (HPLC), (45)Sc NMR, electron spin resonance (ESR), UV/Vis-NIR and Raman spectroscopy provided the experimental evidence for the caging of the five-atom Sc(3)CH cluster inside the C(80) cage isomer with icosahedral symmetry. The proposed new structure was confirmed by DFT calculations, which gave a closed shell and large energy gap structure. Thus a pyramidal Sc(3)CH cluster and the I(h)-C(80) cage were shown to be the most stable configuration for Sc(3)CH@C(80) whereas alternative structures give a smaller bonding energy as well as a smaller energy gap.

45Sc Solid State NMR Spectroscopy – A Complementary Tool to X‐ray Crystallography for Structure Determination of Intermetallic Compounds

“…As Figure 9 indicates the Sc site giving rise to the signal at 720 ppm shows the stronger attenuation in this experiment, indicating the stronger stronger 29 Si- 45 Sc magnetic dipole-dipole coupling, thereby confirming the above assignment to the Sc(1) site. 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 equivalence of these scandium sites is indeed evident in the 45 Sc MAS-NMR spectrum (top trace of Figure 10), the resolution is poor owing to the small differences in magnetic shielding and the presence of substantial second-order quadrupolar broadening effects affecting the lineshapes of the central |1/2> <-> |-1/2> Zeeman transitions.…”

“…While the Sc1 sites have six nearest silicon neighbours at a distance of 280 pm and six nearest gold neighbours at a distance of 316 pm, the situation for the Sc2 sites is exactly the reverse one. As a result, Sc(1) experiences significantly stronger 29 Si- 45 Sc magnetic dipole-dipole coupling than Sc(2) as the strength of this interaction scales with the inverse cube of the internuclear distances.…”

“…These dipolar couplings can be measured selectively using the technique of 45 This experiment measures the attenuation of the 45 Sc NMR signal that is caused by 29 Si spin inversion during the magic angle spinning rotor cycle. As Figure 9 indicates the Sc site giving rise to the signal at 720 ppm shows the stronger attenuation in this experiment, indicating the stronger stronger 29 Si- 45 Sc magnetic dipole-dipole coupling, thereby confirming the above assignment to the Sc(1) site.…”

“…In the past most 45 Sc solid state NMR studies have been performed on diverse complex oxides, zeolite-based materials, glasses , organic-inorganic hybrid materials [24], doped lanthanum fluoride nanoparticles [25], antiferromagnetic thiospinels [26,27], and fullerenes [28][29][30][31][32]. Besides standard methodology, a variety of modern techniques like multi-quantum magic angle spinning NMR have been applied to diverse oxidic scandium compounds [33][34][35][36] in order to get more detailed structural information on these materials, e. g. differentiation of the scandium sites in organically templated scandium fluorophosphate frameworks [37], to work out the influence of the coordination number on the isotropic chemical shift in stabilized zirconia [38] and to systemize the 45 Sc chemical shifts in several basic inorganic scandium compounds [39].…”

Endohedral fullerene with μ3-carbido ligand and titanium-carbon double bond stabilized inside a carbon cage

“…The best method for the synthesis of TiLu 2 C 81 was found to be a reactive atmosphere method with methane such as the method used in our group earlier to synthesize Sc 3 CH@C 80 (ref. 40). Arc-discharge synthesis in the presence of CH 4 yields TiLu 2 C 81 as one of the main EMF products (Fig.…”