Fe(Cp)(CO)2

Formula: C₇H₅FeO₂
Molecular weight: 176.958
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Reaction thermochemistry data

Data compiled by: José A. Martinho Simões

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Individual Reactions

C₇H₆FeO₂ (solution) = C₇H₅FeO₂ (solution) + (solution)

By formula: C₇H₆FeO₂ (solution) = C₇H₅FeO₂ (solution) + H (solution)

Quantity	Value	Units	Method	Reference	Comment
Δ_rH°	238.9 ± 4.2	kJ/mol	EChem	Parker, Handoo, et al., 1991	solvent: Acetonitrile; Please also see Tilset and Parker, 1989. The reaction enthalpy was obtained from the pKa of the hydride complex (MH), 19.4, and from the oxidation potential of the anion (M-), Fe(Cp)(CO)2(-), by using the equation: ΔH_rxn [kJ/mol] = 5.71pKa(MH) + 96.485(Eo)ox(M-) + C. C is a constant that was calculated as 248.9 kJ/mol Parker, Handoo, et al., 1991, by adjusting the previous equation to the calorimetrically derived values for the reactions Cr(Cp)(CO)3(H)(solution) = Cr(Cp)(CO)3(solution) + H(solution), 257.3 ± 4.2 kJ/mol, and Cr(Cp)(CO)2(PPh3)(H)(solution) = Cr(Cp)(CO)2(PPh3)(solution) + H(solution), 250.2 ± 4.2 kJ/mol Kiss, Zhang, et al., 1990. C depends on the solvent and on the reference electrode. The value given implies that the electrode potentials are referenced to ferrocene/ferricinium electrode

C₁₄H₁₀Fe₂O₄ (solution) = 2C₇H₅FeO₂ (solution)

By formula: C₁₄H₁₀Fe₂O₄ (solution) = 2C₇H₅FeO₂ (solution)

Quantity	Value	Units	Method	Reference	Comment
Δ_rH°	>98.4	kJ/mol	ES/EChem	Pugh and Meyer, 1988	solvent: Acetonitrile; The lower limit is the reaction Gibbs energy
Δ_rH°	96.	kJ/mol	KinS	Cutler and Rosenblum, 1976	solvent: Benzene; The reaction enthalpy was derived from the activation enthalpy of the disproportionation reaction [Fe(Cp)(C5H4COMe)(CO)2]2(solution) = 0.5[Fe(Cp)(CO)2]2(solution) + 0.5[Fe(C5H5COMe)(CO)2]2(solution), 113. ± 11. kJ/mol, whose rate-determining step corresponds to Fe-Fe cleavage after isomerization of the complex with two bridging carbonyls to a "linear" (no bridging carbonyls) structure Cutler and Rosenblum, 1976. The enthalpy of this isomerization was estimated as 17. kJ/mol Cutler and Rosenblum, 1976

References

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Parker, Handoo, et al., 1991
Parker, V.D.; Handoo, K.L.; Roness, F.; Tilset, M., J. Am. Chem. Soc., 1991, 113, 7493. [all data]

Tilset and Parker, 1989
Tilset, M.; Parker, V.D., J. Am. Chem. Soc., 1989, 111, 6711; ibid. 1990. [all data]

Kiss, Zhang, et al., 1990
Kiss, G.; Zhang, K.; Mukerjee, S.L.; Hoff, C.; Roper, G.C., J. Am. Chem. Soc., 1990, 112, 5657. [all data]

Pugh and Meyer, 1988
Pugh, J.R.; Meyer, T.J., J. Am. Chem. Soc., 1988, 110, 8245. [all data]

Cutler and Rosenblum, 1976
Cutler, A.R.; Rosenblum, M., J. Organometal. Chem., 1976, 120, 87. [all data]

Notes

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Symbols used in this document:

Δ_rH° Enthalpy of reaction at standard conditions
Data from NIST Standard Reference Database 69: NIST Chemistry WebBook
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