Topological Organic Chemistry. Polyhedranes and Prismanes

Schultz, Harry P.

doi:10.1021/jo01016a005

Cited by 88 publications

(46 citation statements)

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“…non-isomeric fullerenes with different stoichiometries, is discussed only very rarely [47 -51]. Interestingly enough, the problem was, probably for the first time, touched by Schultz [52]. Clearly enough, further exploration of the rules behind the relative stabilities of isomeric and nonisomeric fullerenes is to be expected.…”

Section: Resultsmentioning

confidence: 99%

C94 IPR isomeric set: large-scale computations of relative stabilities based on the Gibbs function

Slanina

Zhao

Uhlı́k

et al. 2003

Journal of Molecular Structure: THEOCHEM

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At present C 94 is one of the highest sets of isomeric fullerenes that has been characterized by 13 C NMR spectra. This contribution reports quantum-chemical computations on the C 94 system. The complete set of 134 isolated-pentagon-rule isomers of C 94 is described by four semiempirical quantum-chemical methods (MNDO, AM1, PM3, and SAM1). The C 94 energetics is also checked with Hartree -Fock SCF calculations in the standard 4-31G basis set (HF/4-31G). The calculations point out a C 2 structure as the system ground state. As energetics itself cannot produce reliable relative stabilities at high temperatures, entropy terms are also computed and the relative-stability problem is entirely treated in terms of the Gibbs function. The lowest-energy structure remains the most populated isomer at higher temperatures. However, several other structures show significant populations at higher temperatures. The six most populated species at the AM1 computational level read: C 2 ; C 2 ; C 1 ; C 1 ; C s ; and C 2 : This selected six-membered isomeric set indeed contains the four symmetries observed in the available experiment (C 2 ; C s ; C 2 ; and C 2 ). This incidence represents a good agreement with the experiment and can be viewed as another evidence that the supposed inter-isomeric thermodynamic equilibrium does exist in experiments. q

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Section: Resultsmentioning

confidence: 99%

C94 IPR isomeric set: large-scale computations of relative stabilities based on the Gibbs function

Slanina

Zhao

Uhlı́k

et al. 2003

Journal of Molecular Structure: THEOCHEM

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“…Moreover, it offers a stabilized, conserved water dimer (though influenced by the carbon cage) that can be used for various spectral characterizations of the prototype hydrogen-bonded aggregate. It also represents an interesting observed species for further computational studies, this experiment-theory symbiosis being always quite common 6,7 in fullerene science, even in its prehistoric times 8,9 before the C 60 breakthrough observation 10 in 1985. In addition to the water 1,2,5 and hydrogen molecule 3,4 containing endohedrals, also encapsulations of other non-metal species inside the fullerene cages have been studied, for example atomic [11][12][13][14][15] and molecular 16,17 nitrogen.…”

Section: This Paper Is Part Of the Jss Focus Issue On Nanocarbons -Inmentioning

confidence: 96%

Computational Comparison of the Water-Dimer Encapsulations intoD₂(22)-C₈₄andD_2d(23)-C₈₄

Slanina

Uhlı́k

Nagase

et al. 2017

ECS J. Solid State Sci. Technol.

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The water dimer encapsulations into D 2 (22)-C 84 and D 2d (23)-C 84 fullerenes are evaluated. The encapsulation energy is computed at the M06-2X/6-31++G** level and it is found that the energy gain upon encapsulation into the D 2 (22)-C 84 and D 2d (23)-C 84 cages is −17.37 and −15.48 kcal/mol, respectively. Encapsulation equilibrium constants are computed using partitions functions based on the M06-2X/6-31++G** molecular data. The yield for (H 2 O) 2 @D 2 (22)-C 84 is higher than for (H 2 O) 2 @D 2d (23)-C 84 , however, the yield ratio decreases with increasing temperature and for high temperatures is close to 2:1. The M06-2X/6-31++G** computed rotational constants are presented for a possible use in detection of the water-dimer endohedrals by rotational spectroscopy in laboratory or interstellar space. The very recent production of C 70 with encapsulated water dimer 1 represents a further example of fullerene endohedrals prepared 2-5 via organic synthesis. Moreover, it offers a stabilized, conserved water dimer (though influenced by the carbon cage) that can be used for various spectral characterizations of the prototype hydrogen-bonded aggregate. It also represents an interesting observed species for further computational studies, this experiment-theory symbiosis being always quite common 6,7 in fullerene science, even in its prehistoric times 8,9 before the C 60 breakthrough observation 10 in 1985. In addition to the water 1,2,5 and hydrogen molecule 3,4 containing endohedrals, also encapsulations of other non-metal species inside the fullerene cages have been studied, for example atomic 11-15 and molecular 16,17 nitrogen. Endohedrals with rare gas atoms, in particular with He, were produced using 18,19 high temperatures (650 o C), high pressures (3000 atm) and a catalyst. Such fullerene encapsulations of non-metals have been computed, [20][21][22][23][24][25] too. This paper continues in the research line with calculations on two C 84 endohedrals containing encapsulated water dimer. [36][37][38] in saturated water vapor increases with increasing temperature. It may be a surprising result but in fact it can easily be rationalized. While the equilibrium constant for the dimer formation decreases with temperature, the saturated pressure increases and actually grows faster. 39 The water dimer formation is described by the usual dimerization equilibrium constant K p,2 in terms of the partial pressures of the components: CalculationsIn fact, the recent evaluation 40 of the water dimerization constant (G3&MP2/AUG-cc-pVQZ level) reaches nearly perfect agreement with the available experimental data.The dimeric-water encapsulations into both C 84 cages (Figure 1) are similarly described by the encapsulation equilibrium constants K p,enc,i :The relative yields of both encapsulates (here represented by the ratio of their partial pressures p -see Eq. 4) can actually be estimated using the ratio of equilibrium constants (2) and (3), especially if the starting amount of both empty fullerenes (or more precisely, their am...

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“…Among polyhedra of chemical interest are those of the 3-connected isogonal polyhedra whose vertex angles fall within the ranges consistent with potentially admissible C-C-C and H-C-C bond angles in the two classes of saturated hydrocarbons C,H,, the polyhedranes and the prismanes (Schultz, 1965). Apart from tetrahedrane and cubane, both of which have ~{ geomemes all the other polyhedrane skeletons are ~ (12-2, 20-1, 24-1, 24-2, 48-1, 60-1, 60-2, 120-1).…”

Section: Selection Of Polyhedramentioning

confidence: 99%

Univalent (monodentate) substitution on convex polyhedra

Knop¹,

Barker²,

White³

1975

Acta Cryst Sect A

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P61ya's enumeration theorem has been used to evaluate, by computer, the numbers N of distinct configurations (= positional isomers) produced by univalent (monodentate) substitution at the vertices of convex polyhedra of crystallographic or stereochemical interest. The values of N are tabulated for a large variety of polyhedra of up to V= 120 vertices and for up to V kinds of structureless substituents. The N have been evaluated not only for the maximum point-group symmetry of each polyhedron but also, for V< 24, for all the subgroup symmetries of the maximum point group. For V> 24 only polyhedra of cubic and icosahedral symmetries are included. An example shows how the tables of N can be used to enumerate pairs of enantiomorphs. The effect of symmetry on N for large values of V is examined. Killam Postdoctoral Fellow, 1968-1970

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Topological Organic Chemistry. Polyhedranes and Prismanes

Cited by 88 publications

References 0 publications

C94 IPR isomeric set: large-scale computations of relative stabilities based on the Gibbs function

C94 IPR isomeric set: large-scale computations of relative stabilities based on the Gibbs function

Computational Comparison of the Water-Dimer Encapsulations intoD₂(22)-C₈₄andD_2d(23)-C₈₄

Univalent (monodentate) substitution on convex polyhedra

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Topological Organic Chemistry. Polyhedranes and Prismanes

Cited by 88 publications

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C94 IPR isomeric set: large-scale computations of relative stabilities based on the Gibbs function

C94 IPR isomeric set: large-scale computations of relative stabilities based on the Gibbs function

Computational Comparison of the Water-Dimer Encapsulations intoD2(22)-C84andD2d(23)-C84

Univalent (monodentate) substitution on convex polyhedra

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Computational Comparison of the Water-Dimer Encapsulations intoD₂(22)-C₈₄andD_2d(23)-C₈₄