Enthalpy of Formation and C−F Bond Enthalpy of Fluorofullerene C₆₀F₃₆

Abstract

The standard molar enthalpy of combustion of fluorofullerene C 60 F 36 was determined by rotating-bomb calorimetry, ∆ c H°m ) -24692 ( 199 kJ‚mol -1 . Using this result and the standard molar enthalpy of sublimation, ∆ sub H°m ) 139 ( 8 kJ‚mol -1 , the values of the standard molar enthalpies of formation of C 60 F 36 in the crystalline and gaseous states were found to be -5362 ( 201 kJ‚mol -1 and -5223 ( 201 kJ‚mol -1 , respectively. The enthalpy of reaction C 60 F 36 (g) ) C 60 (g) + 36F(g) was calculated, ∆ r H°m(298.15 K) ) (10617 ( 202) kJ‚mol -1 , or 294.9 ( 5.6 kJ‚mol -1 per one C-F bond. The comparison with the enthalpy of reaction C 60 F 48 ) C 60 (g) + 48F(g), ∆ r H°m(298.15 K) ) 287.5 ( 3.5 kJ‚mol -1 per C-F bond leads to a preliminary conclusion that C-F bond enthalpy decreases with amount of F atoms attached to the fullerene cage.

Mass spectrometry, photoelectron spectroscopy, and quantum chemical studies of fluorofullerene dianions

“…This hypothesis is supported by our observations of the partial or even complete defluorination of fullerene fluorides upon the increase of the donor concentration. The lower strength of C F bonds in fluorofullerenes relative to sterically unstrained organic compounds (the average C F bond energy in C 60 F 2n does not exceed 300 kJ/mol and decreases from C 60 F 36 to C 60 F 48 ) [28,29] and higher stability of the closed-shell anionic species can serve as additional driving forces for the processes of F atom loss and charging. On one hand, such defluorination processes that accompany ESI MS of fluorofullerenes can be regarded as a drawback of the ESI-based method of anion production as compared to the gas-phase electron-capture techniques, since it is more difficult to generate molecular ions or doubly charged anions of the parent molecules.…”

Application of 9‐nitroanthracene as a matrix for laser desorption/ionization analysis of fluorinated fullerenes

“…with ca. 3.5 eV of excess energy, and the experimentally determined average CF BDE for C 60 F 36 is 3.0 eV 16. In contrast, the formation of the [C 60 F 18 ] − .…”

Interplay of Thermochemistry and Structural Chemistry, the Journal (Volume 14, 2003) and the Discipline

“…There have been thermochemical studies of some fullerenes including some highly hydrogenated and fluorinated derivatives. For example, the enthalpies of formation and the derived mean C H and C F bond energies in C 60 H 36 [10] and C 60 F 36 [11] have been determined. However, we know of no thermochemical studies of any of the endohedral fullerene derivatives.…”