Enthalpy of combustion of 1,4-dimethylcubane dicarboxylate

Kirklin, Duane R.; Churney, K.L.; Domalski, Eugene S.

doi:10.1016/0021-9614(89)90098-0

Cited by 39 publications

(40 citation statements)

References 11 publications

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“…Table 2 reports the calculated and experimental SE values of cubane. The homodesmotic reaction (1) is designed for cubane and the calculated value would be compared with the data of previous studies [7][8][9]18] in order to verify that computational results at the B3LYP/6-31G* level via the homodesmotic process are reliable for the calculated SE values of cubane derivatives. Through the homodesmotic reaction (1) at the B3LYP/6-31G* level, the SE value of cubane is 169.13 kcal/mol.…”

Section: Methodsmentioning

confidence: 99%

“…For large molecule, various conditions can yield great discrepancies. For example, the reported experimental values of SE for cubane are 157 kcal/mol, 161.2 kcal/mol and 162.7 kcal/mol, respectively [7][8][9]. The reported strain energy of cubane was derived from the enthalpies of formation of solid cubane and sublimation enthalpy of cubane [7].…”

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

Strain energies of cubane derivatives with different substituent groups

Fan

Xia

et al. 2008

Journal of Hazardous Materials

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Section: Methodsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Strain energies of cubane derivatives with different substituent groups

Fan

Xia

et al. 2008

Journal of Hazardous Materials

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“…), adamantane (PA = 175.7 kcal mol À1 , [11] E str = 6.3 kcal mol À1 [12] ), and cubane [13] (PA = ca 200 kcal mol À1 , [7,9] E str = 161 kcal mol À1 [14] ). For these systems the question remains: How much does the strain energy affect the proton affinity of a saturated hydrocarbon and to what extent should isomerizations be considered?…”

mentioning

confidence: 99%

The Protonation of Cubane Revisited

et al. 2004

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Protonation of saturated hydrocarbons is the simplest and practically most important electrophilic reaction.[1] Small alkanes like methane, ethane, and isobutane [2] form welldefined protonated species, and their experimental proton affinities (PAs) are excellently reproduced computationally. [3][4][5] However, the current data on the protonations of strained hydrocarbons are rather controversial, and facile rearrangements are thought to account for the difficulties encountered in measuring the PAs.[6] Cyclopropane (strain energy(E str ) = 27.2 kcal mol À1 ) is an exception because the number of energetic downhill paths is very limited and the barrier for the ring opening of corner-protonated C 3 H 7 + to the 2-propyl cation is high. The experimental PA of cyclopropane (179.4 kcal mol À1 [7] ) is well reproduced computationally (179.3 kcal mol À1 at CCSD(T)/cc-pVTZ//CCSD(T)/cc-pVDZ for corner-protonated C 3 H 7 + ).[8] In contrast to cyclopropane which displays secondary CÀH bonds only, a surprisingly small range of PAs is characteristic for a number of hydrocarbons with tertiary C À H bonds. These hydrocarbons differ considerably in their strain energies, for example, dodecahedrane (PA = 201.7 kcal mol À1 , [9] E str = 65.4 kcal mol), adamantane (PA = 175.7 kcal mol À1 , [11] E str = 6.3 kcal mol À1 [12] ), and cubane [13] (PA = ca 200 kcal mol À1 , [7,9] E str = 161 kcal mol À1 [14] ). For these systems the question remains: How much does the strain energy affect the proton affinity of a saturated hydrocarbon and to what extent should isomerizations be considered? The experimental PA of cubane (1) measured by ion-cyclotron resonance spectroscopy [9] is surprisingly low and was recently questioned by Koppel et al. [15] on the basis that 1 rearranges rapidly to cuneane so that the PA is attributed to the energy change of the entire protonation/rearrangement/deprotonation process. However, cuneane is also highly strained, so where one does stop? Are there any other rearrangement paths for protonated cubane? Herein we address both computationally and experimentally the question to what extent the cubane cage is able to survive electrophilic attack [16] and what the most favorable paths for the reaction of 1 with a proton are.Despite enormous strain, cubane [15,17,18] is kinetically quite stable because breaking just one CÀC bond causes only minor structural changes and hence only little relief of strain. However, cleavage of a second CÀC bond is highly exothermic and followed by rapid rearrangements. For instance, thermolysis [16,19] and single-electron oxidation [20] of 1 leads to cyclooctatetraene. In contrast, mild radical reagents [21] lead to substitution products with conservation of the cubane cage. [22] Electrophilic cubane conversions are limited to reactions of soft electrophiles like metal ions, [18] and a number of fascinating rearrangements (e.g., to syn-tricyclooctadiene (2) with Pd 2+ and to cuneane (3) with Ag + and Li + ) are preparatively useful. [18,23] The attack of a proton on cubane i...

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“…Indeed, cubane has been used as a paradigm for the group and concomitant understanding of strain energy 107 . Yet recently, through analysis of its 1,4-dicarbomethoxy derivative 110 , new derived values for the enthalpy of formation of solid and gaseous cubane have been suggested which differ from the earlier measured quantities by ca 45 kJ mol −1 .…”

Section: F Do Many Rings Mean Many Problems?mentioning

confidence: 99%