bis(η⁵-Cyclopentadienyl) chromium

Formula: C₁₀H₁₀Cr
Molecular weight: 182.1825
IUPAC Standard InChI: InChI=1S/2C5H5.Cr/c2*1-2-4-5-3-1;/h2*1-5H;
IUPAC Standard InChIKey: OXPNGPODCRFNTM-UHFFFAOYSA-N
CAS Registry Number: 1271-24-5
Chemical structure:
This structure is also available as a 2d Mol file
Other names: Chromocene; bis(η5-cyclopenta-2,4-dien-1-yl)chromium
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Phase change data

Go To: Top, Gas phase ion energetics data, References, Notes

Data compiled as indicated in comments:
TRC - Thermodynamics Research Center, NIST Boulder Laboratories, Chris Muzny director
AC - William E. Acree, Jr., James S. Chickos
MS - José A. Martinho Simões
DH - Eugene S. Domalski and Elizabeth D. Hearing

Quantity	Value	Units	Method	Reference	Comment
T_fus	452.1	K	N/A	Baev, Barkatin, et al., 1979	Crystal phase 1 phase; Uncertainty assigned by TRC = 0.5 K; TRC
Quantity	Value	Units	Method	Reference	Comment
Δ_subH°	71.0 ± 1.3	kJ/mol	CC-SB	Baev, Barkatin, et al., 1984	Other values for the enthalpy of sublimation have been reported: 62.8 ± 4.2 kJ/mol Pilcher and Skinner, 1982 and 69.9 ± 1.7 kJ/mol Tel'noi and Rabinovich, 1977; MS
Δ_subH°	71.0	kJ/mol	N/A	Baev, Barkatin, et al., 1984, 2	AC
Δ_subH°	62.8 ± 4.2	kJ/mol	N/A	Pilcher and Skinner, 1983	See also Tel'noi, Kirynov, et al., 1975.; AC

Enthalpy of vaporization

Δ_vapH (kJ/mol)	Temperature (K)	Reference	Comment
49.5 ± 1.5	485.	Baev, Barkatin, et al., 1984, 2	Based on data from 452. to 519. K.; AC

Temperature of phase transition

T_trs (K)	Initial Phase	Final Phase	Reference	Comment
160. to 230.	crystaline, II	crystaline, I	Pommier and Azokpota, 1976	S = 1.5 J/mol*K Lambda type transition.; DH

Enthalpy of phase transition

ΔH_trs (kJ/mol)	Temperature (K)	Initial Phase	Final Phase	Reference	Comment
0.265	99.7	crystaline, II	crystaline, I	Rabinovich, Nistratov, et al., 1978	Lambda transition between 75 to 140 K with a maximum at 99.7 K and another flat peak at 118 K.; DH
0.265	99.5	crystaline, II	crystaline, I	Rabinovich, Nistratov, et al., 1975	Lambda transition between 75 to 140 K with a maximum at 99.7 K and another flat peak at 118 K.; DH

Entropy of phase transition

ΔS_trs (J/mol*K)	Temperature (K)	Initial Phase	Final Phase	Reference	Comment
2.55	99.7	crystaline, II	crystaline, I	Rabinovich, Nistratov, et al., 1978	Lambda; DH
2.57	99.5	crystaline, II	crystaline, I	Rabinovich, Nistratov, et al., 1975	Lambda; DH

In addition to the Thermodynamics Research Center (TRC) data available from this site, much more physical and chemical property data is available from the following TRC products:

Gas phase ion energetics data

Go To: Top, Phase change data, References, Notes

Data compiled as indicated in comments:
LLK - Sharon G. Lias, Rhoda D. Levin, and Sherif A. Kafafi
RDSH - Henry M. Rosenstock, Keith Draxl, Bruce W. Steiner, and John T. Herron

View reactions leading to C₁₀H₁₀Cr⁺ (ion structure unspecified)

Ionization energy determinations

IE (eV)	Method	Reference	Comment
5.50	PE	Rabalais, Werme, et al., 1972	LLK
6.3 ± 0.1	EI	Muller and D'Or, 1967	RDSH
5.70	PE	Cauletti, Green, et al., 1980	Vertical value; LLK
5.71	PE	Evans, Green, et al., 1974	Vertical value; LLK

Appearance energy determinations

Ion	AE (eV)	Other Products	Method	Reference	Comment
C₅H₅Cr⁺	12.8 ± 0.1	?	EI	Muller and D'Or, 1967	RDSH
Cr⁺	14.6 ± 0.3	?	EI	Muller and D'Or, 1967	RDSH

References

Go To: Top, Phase change data, Gas phase ion energetics data, Notes

Baev, Barkatin, et al., 1979
Baev, A.K.; Barkatin, A.A.; Gubin, S.P.; Dyagileva, S.P., Thermodynamics of phase transitions and vapor state of some compounds of elements with incomplete d-shells in Vses. Konf. po Kalorimetrii i Khim. Termodinamike, 8th, Ivanovo, p 386-389, 1979. [all data]

Baev, Barkatin, et al., 1984
Baev, A.K.; Barkatin, A.A.; Dargileva, L.M., Vesti Akad. Navuk BSSR, Ser. Khim. Navuk, 1984, 60.. [all data]

Pilcher and Skinner, 1982
Pilcher, G.; Skinner, H.A., In The Chemistry of the Metal-Carbon Bond Wiley: New York, Hartley, F. R.; Patai, S., ed(s)., 1982. [all data]

Tel'noi and Rabinovich, 1977
Tel'noi, V.I.; Rabinovich, I.B., Russ. Chem. Rev., 1977, 46, 689. [all data]

Baev, Barkatin, et al., 1984, 2
Baev, A.K.; Barkatin, A.A.; Dyagileva, L.M., Vestsi Akad. Navuk BSSR Ser. Khim. Navuk, 1984, 60. [all data]

Pilcher and Skinner, 1983
Pilcher, G.; Skinner, H.A., Thermochemistry of organometallic compounds, 1983, 43-90, https://doi.org/10.1002/9780470771686.ch2 . [all data]

Tel'noi, Kirynov, et al., 1975
Tel'noi, V.I.; Kirynov, K.V.; Ermolaev, V.I.; Rabinovich, I.B., Dokl. Akad. Nauk SSSR, 1975, 220, 1088. [all data]

Pommier and Azokpota, 1976
Pommier, C.; Azokpota, C., Study of phase transitions in metallocenes by determining specific heat curves, J. Calorim. Anal. Therm. [C.R.], 1976, 3-6, 1-8. [all data]

Rabinovich, Nistratov, et al., 1978
Rabinovich, I.B.; Nistratov, V.P.; Sheiman, M.S.; Burchalova, G.V., Heat capacities of dicyclopentadienyl compounds of vanadium, chromium, manganese, cobalt, and nickel, J. Chem. Thermodynam., 1978, 10, 523-536. [all data]

Rabinovich, Nistratov, et al., 1975
Rabinovich, I.B.; Nistratov, V.P.; Sheiman, M.S.; Burchalova, G.V., Heat capacity and transitions in solid state. Dicyclopentadienyl compounds of transition elements,Quatrieme Conference International de Thermodynamique Chimique II, Thermophysiques (capacites thermiques) pp., 1975, 69-76, 136. [all data]

Rabalais, Werme, et al., 1972
Rabalais, J.W.; Werme, L.O.; Bergmark, T.; Karlsson, L.; Hussain, M.; Siegbahn, K., Electron spectroscopy of open-shell systems: spectra of Ni(C₅H₅)₂, Fe(C₅H₅)₂, Mn(C₅H₅)₂, and Cr(C₅H₅)_Å2, J. Chem. Phys., 1972, 57, 1185. [all data]

Muller and D'Or, 1967
Muller, J.; D'Or, L., Massenspektrometrische Untersuchungen an Dicyclopentadienylkomplexen von Ubergangsmetallen, J.Organometal. Chem., 1967, 10, 313. [all data]

Cauletti, Green, et al., 1980
Cauletti, C.; Green, J.C.; Kelly, M.R.; Powell, P.; Van Tilborg, J., Photoelectron spectra of metallocenes, J. Electron Spectrosc. Relat. Phenom., 1980, 19, 327. [all data]

Evans, Green, et al., 1974
Evans, S.; Green, M.L.H.; Jewitt, B.; King, G.H.; Orchard, A.F., Electronic structures of metal complexes containing the π-cyclopentadienyl and related ligands Part 2. He I photoelectron spectra of the open-shell metallocenes, J. Chem. Soc. Faraday Trans. 2, 1974, 70, 356. [all data]

Notes

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Symbols used in this document:

AE	Appearance energy
T_fus	Fusion (melting) point
T_trs	Temperature of phase transition
ΔH_trs	Enthalpy of phase transition
ΔS_trs	Entropy of phase transition
Δ_subH°	Enthalpy of sublimation at standard conditions
Δ_vapH	Enthalpy of vaporization

Data from NIST Standard Reference Database 69: NIST Chemistry WebBook
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bis(η5-Cyclopentadienyl) chromium