Thermodynamic characteristics of bis(η6-ethylbenzene)chromium fulleride

• Published in: Russian Journal of Physical Chemistry A Vol. 85; no. 8; pp. 1423 - 1429
• Main Authors: Markin, A. V., Ruchenin, V. A., Smirnova, N. N., Abakumov, G. A., Markin, G. V., Shevelev, Yu. A., Kuropatov, V. A., Lopatin, M. A., Cherkasov, V. K., Domrachev, G. A.
• Format: Journal Article
• Language: English
• Published: Dordrecht SP MAIK Nauka/Interperiodica 01-08-2011
• Subjects: Chemistry; Chemistry and Materials Science; Physical Chemistry; Physical Chemistry of Nanoclusters and Nanomaterials; heat capacity; calorimetry; entropy; enthalpy; fullerides
• ISSN: 0036-0244; 1531-863X
• DOI: 10.1134/S003602441108022X

The temperature dependence of heat capacity of crystalline bis(η
6
-ethylbenzene)chromium fulleride [(η
6
-EtPh)
2
Cr]
·+
[C
60
]
·−
was studied in adiabatic vacuum calorimeter in the range of 6.7 to 344 K with an error of ±0.3%. Dependence of the parameters of EPR signal of bis(η
6
-ethylbenzene)chromium fulleride on temperature was studied by electron paramagnetic resonance (EPR) in the range of 120 to 290 K. In the range of 204 to 246 K, upon heating, reversible endothermic transformation was recorded, which is caused by the dissociation of dimer (C
60
−
)
2
and formation of fulleride [(η
6
-EtPh)
2
Cr]
·+
[C
60
]
·−
; its standard thermodynamic parameters were estimated and analyzed. Standard thermodynamic functions were calculated by the experimental data obtained: heat capacity, enthalpy, entropy, and Gibbs function of fulleride dimmer in the range of
T
→ 0 to 204 K and monomer complex [(η
6
-EtPh)
2
Cr]
·+
[C
60
]
·−
in the range of 246 to 344 K. Standard thermodynamic properties of fulleride under study, fullerides studied earlier, and fullerite C
60
were compared.