Abstract:The endohedral fullerene CH
4
@C
60
, in which each C
60
fullerene cage encapsulates a single methane molecule, has been synthesized for the first time. Methane is the first organic molecule, as well as the largest, to have been encapsulated in C
60
to date. The key orifice contraction step, a photochemical desulfinylation of an open fullerene, was completed, even though it is inhibited by the endohedral molecule. The c… Show more
“…Allowing for the nonrigidity of the lattice, not considered in the Devonshire cell model, introduces two effects changing the quantum treatment of these systems: (a) the host–guest (molecule–crystal) interaction energy is minimized by the relaxation of the lattice, and (b) the orientation‐dependent lattice relaxations, through coupling of the guest rotations with pseudorotation of the host, induce a significant change, in fact a decrease of the effective rotational constants. Recently, quantum studies of molecules trapped in cages found renewed interest, especially with regard to the joint treatment of translation–rotation states. Answering the question whether these systems are quasistructural or not would require detailed experimental high‐resolution spectroscopic studies and variational rovibrational treatments, both hindered by the size of some of these systems.…”
Section: On the Separation Of Vibrations And Rotationsmentioning
The concept of quasistructural molecules is introduced. For quasistructural molecules (a) the notion of a static equilibrium structure, corresponding to a minimum on the potential energy surface of the molecule, loses its strict meaning, (b) internal
“…Allowing for the nonrigidity of the lattice, not considered in the Devonshire cell model, introduces two effects changing the quantum treatment of these systems: (a) the host–guest (molecule–crystal) interaction energy is minimized by the relaxation of the lattice, and (b) the orientation‐dependent lattice relaxations, through coupling of the guest rotations with pseudorotation of the host, induce a significant change, in fact a decrease of the effective rotational constants. Recently, quantum studies of molecules trapped in cages found renewed interest, especially with regard to the joint treatment of translation–rotation states. Answering the question whether these systems are quasistructural or not would require detailed experimental high‐resolution spectroscopic studies and variational rovibrational treatments, both hindered by the size of some of these systems.…”
Section: On the Separation Of Vibrations And Rotationsmentioning
The concept of quasistructural molecules is introduced. For quasistructural molecules (a) the notion of a static equilibrium structure, corresponding to a minimum on the potential energy surface of the molecule, loses its strict meaning, (b) internal
“…Encapsulation of Li + ion inside the C 60 cage was done experimentally by Hiroshi et al 47 Experimentally it is reported that La atom can be inserted into the cavity of C 72 , C 74 , C 82 cages 48–50 . Encapsulation of H 2, 51,52 H 2 O, 53 HF, 54 CH 4 55 molecules inside fullerene were done using the “molecular surgery” technique. Various theoretical works on the encapsulation of different metals and noble gases inside the C 60 cage have been reported 56–59 .…”
Density functional theory (DFT) based calculations have been carried out for the endohedral encapsulation of magnesium dimer inside fullerene, that is, Mg 2 @C 60 . It is observed that the minimum energy structure of the Mg 2 @C 60 system is C 2h symmetry. The Mg Mg bond distance in the Mg 2 @C 60 system is much shorter than that in the free Mg 2 and Mg 2 2+ ion. The formation of the endohedral Mg 2 @C 60 system is thermochemically spontaneous in nature. The natural bond orbital (NBO) analysis showed the presence of an Mg 2 2+ fragment with an Mg Mg bond inside the C 60 cage. The electron density descriptors have identified the covalency in the Mg Mg bond. A non-nuclear attractor (NNA) is present in the middle of the two Mg-atoms. The bonding interaction between the Mg 2 and C 60 fragments is ionic in nature and the [Mg 2 2+ ] and [C 60 2− ] represent the bonding pattern in the Mg 2 @C 60 system. The designed endohedrally encapsulated system behaves as an electride. K E Y W O R D S electride, electron localization function (ELF) basin, endohedrally encapsulated fullerene, energy decomposition analysis (EDA), non-nuclear attractor (NNA)
“…Upon irradiation of Ar@4 for 35 h under these conditions, at 50 1C using a low-pressure sodium lamp, the bis(hemiketal) Ar@5 was obtained in 26% yield of isolated product. Our previously reported photochemical desulfinylation of CH 4 @4 led to the corresponding bis(hemiketal) CH 4 @5 in only 13% yield under the same conditions, 19 indicating that contraction of the cage-opening is less inhibited by argon, the smaller endohedral species.…”
mentioning
confidence: 85%
“…by closure of the orifice of CH 4 @3 to obtain CH 4 @C 60 . 19 Herein, we report that high encapsulation of argon by 3 can be achieved under similar conditions, and closure allows synthesis of Ar@C 60 with a step-change improvement in argon incorporation, mass recovery and yield when compared to the direct encapsulation method.…”
mentioning
confidence: 94%
“…Clean and high-yielding oxidation of Ar@3 with dimethyldioxirane gave the sulfoxide Ar@4, and we now applied conditions for photochemical desulfinylation of Ar@4 that were developed for our synthesis of CH 4 @C 60 . 19 Desulfinylation is the first of the 'closure' steps that suture the orifice of the opencage fullerene and a similar photochemical ring-contraction by removal of the sulfinyl group (SO) of other sulfoxide open-cage endofullerenes has been reported, using visible-light irradiation in toluene or benzene. 14,25 Photochemical desulfinylative ring-contraction of sulfoxide 4 re-forms fullerene 2 which is unstable under the reaction conditions, but using a vigorously stirred two-phase mixed solvent system of toluene, acetonitrile and acetic acid (10% v/v aqueous) allows in situ trapping of 2 as the more stable bis(hemiketal) 5.…”
Synthesis of Ar@C60 is described, using a route in which high-pressure argon filling of an open-fullerene and photochemical desulfinylation are the key steps for >95% encapsulation of the noble gas....
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