Nickelocene

Formula: C₁₀H₁₀Ni
Molecular weight: 188.8798
IUPAC Standard InChI: InChI=1S/2C5H5.Ni/c2*1-2-4-5-3-1;/h2*1-5H;
IUPAC Standard InChIKey: FOOKRXHSBKEWSE-UHFFFAOYSA-N
CAS Registry Number: 1271-28-9
Chemical structure:
This structure is also available as a 2d Mol file
Other names: Nickel, di-π-cyclopentadienyl-; Dicyclopentadienylnickel; Nickel, bis(η5-2,4-cyclopentadien-1-yl)-; Nickel, dicyclopentadienyl-; bis(η5-Cyclopentadienyl) nickel; Bis(cyclopentadienyl)nickel (II); Nickel, compd with π-cyclopentadienyl (1:2); π-Cyclopentadienyl compd. with nickel; Di-π-cyclopentadienylnickel; Nikelocen; Nickel, bis(η5-cyclopentadienyl)-; Bis(η5-2,4-cyclopentadien-1-yl)nickel
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Other data available:
- Mass spectrum (electron ionization)
Data at other public NIST sites:
- X-ray Photoelectron Spectroscopy Database, version 5.0
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Gas phase thermochemistry data

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Data compiled by: José A. Martinho Simões

Quantity	Value	Units	Method	Reference	Comment
Δ_fH°_gas	85.33 ± 0.55	kcal/mol	Review	Martinho Simões
Δ_fH°_gas	82.7 ± 1.1	kcal/mol	Review	Martinho Simões	Selected data.
Δ_fH°_gas	80.11 ± 0.69	kcal/mol	Review	Martinho Simões
Δ_fH°_gas	79.71 ± 0.74	kcal/mol	Review	Martinho Simões

Condensed phase thermochemistry data

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Data compiled as indicated in comments:
MS - José A. Martinho Simões
DH - Eugene S. Domalski and Elizabeth D. Hearing

Quantity	Value	Units	Method	Reference	Comment
Δ_fH°_solid	68.24 ± 0.53	kcal/mol	Review	Martinho Simões	MS
Δ_fH°_solid	65.6 ± 1.1	kcal/mol	Review	Martinho Simões	Selected data.; MS
Δ_fH°_solid	63.03 ± 0.67	kcal/mol	Review	Martinho Simões	MS
Δ_fH°_solid	62.6 ± 0.7	kcal/mol	CC-SB	Chipperfield, Sneyd, et al., 1979	Value corrected based on a set of ancillary data by J.A. Martinho Sim�es; The enthalpy of combustion is not reported in Chipperfield, Sneyd, et al., 1979.; MS
Quantity	Value	Units	Method	Reference	Comment
Δ_cH°_solid	-1405.0 ± 1.0	kcal/mol	CC-SB	Tel'noi and Rabinovich, 1977	MS
Δ_cH°_solid	-1407.6 ± 0.41	kcal/mol	CC-SB	Tel'noi, Kirynov, et al., 1975	Please also see Pedley and Rylance, 1977.; MS
Δ_cH°_solid	-1345.1 ± 0.60	kcal/mol	CC-SB	Wilkinson, Pauson, et al., 1954	Please also see Cox and Pilcher, 1970.; MS
Quantity	Value	Units	Method	Reference	Comment
S°_{solid,1 bar}	60.49	cal/mol*K	N/A	Rabinovich, Nistratov, et al., 1978	DH
S°_{solid,1 bar}	60.47	cal/mol*K	N/A	Rabinovich, Nistratov, et al., 1975	DH

Constant pressure heat capacity of solid

C_p,solid (cal/mol*K)	Temperature (K)	Reference	Comment
49.09	298.15	Rabinovich, Nistratov, et al., 1978	T = 5 to 300 K.; DH
40.9	298.	Azokpota, Calvarin, et al., 1976	T = 130 to 300 K.; DH
49.14	298.15	Rabinovich, Nistratov, et al., 1975	T = 5 to 298.15 K.; DH

Phase change data

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Data compiled as indicated in comments:
MS - José A. Martinho Simões
AC - William E. Acree, Jr., James S. Chickos
DH - Eugene S. Domalski and Elizabeth D. Hearing

Quantity	Value	Units	Method	Reference	Comment
Δ_subH°	17.1 ± 0.1	kcal/mol	CC-SB	Torres-Gómez, Barreiro-Rodríguez, et al., 1988	Other values for the enthalpy of sublimation have been reported: 17.3 ± 0.31 kcal/mol Turnbull, 1967 and 16.8 ± 0.36 kcal/mol Baev, Barkatin, et al., 1984.; MS
Δ_subH°	16.8 ± 0.36	kcal/mol	N/A	Baev, Barkatin, et al., 1984, 2	AC
Δ_subH°	17.3 ± 0.31	kcal/mol	MM	Pilcher and Skinner, 1983	Based on data from 353. to 419. K. See also Tel'noi, Kirynov, et al., 1975 and Turnbull, 1967, 2.; AC

Temperature of phase transition

T_trs (K)	Initial Phase	Final Phase	Reference	Comment
170. to 240.	crystaline, II	crystaline, I	Pommier and Azokpota, 1976	S = 5.2 J/mol*K; DH
170. to 240.	crystaline, II	crystaline, I	Azokpota, Calvarin, et al., 1976	S = 5.3 J/mol*K No peak is observed on heat capacity curve, but a deviation from normal variation occurs between 170 to 240 K.; DH

Enthalpy of phase transition

ΔH_trs (kcal/mol)	Temperature (K)	Initial Phase	Final Phase	Reference	Comment
0.0435	100. to 190.	crystaline, II	crystaline, I	Rabinovich, Nistratov, et al., 1978	Lambda transition over the temperature range 100 to 190 K.; DH
0.0435	100. to 190.	crystaline, II	crystaline, I	Rabinovich, Nistratov, et al., 1975	Lambda transition.; DH

Entropy of phase transition

ΔS_trs (cal/mol*K)	Temperature (K)	Initial Phase	Final Phase	Reference	Comment
0.320	100. to 190.	crystaline, II	crystaline, I	Rabinovich, Nistratov, et al., 1978	Lambda; DH
0.315	100. to 190.	crystaline, II	crystaline, I	Rabinovich, Nistratov, et al., 1975	Lambda; DH

Gas phase ion energetics data

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Data evaluated as indicated in comments:
HL - Edward P. Hunter and Sharon G. Lias

Data compiled as indicated in comments:
LL - Sharon G. Lias and Joel F. Liebman
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 C₁₀H₁₀Ni⁺ (ion structure unspecified)

Quantity	Value	Units	Method	Reference	Comment
Proton affinity (review)	223.6	kcal/mol	N/A	Hunter and Lias, 1998	HL
Quantity	Value	Units	Method	Reference	Comment
Gas basicity	216.8	kcal/mol	N/A	Hunter and Lias, 1998	HL

Ionization energy determinations

IE (eV)	Method	Reference	Comment
6.24	EQ	Ryan, Eyler, et al., 1992	T = 350K; LL
6.8 ± 0.1	EI	Begun and Compton, 1973	LLK
6.2	PE	Rabalais, Werme, et al., 1972	LLK
6.50 ± 0.25	EI	Flesch, Junk, et al., 1972	LLK
6.8	EI	Schissel, McAdoo, et al., 1968	RDSH
7.2 ± 0.1	EI	Muller and D'Or, 1967	RDSH
6.75	EI	Foffani, Pignataro, et al., 1967	RDSH
6.51	PE	Evans, Green, et al., 1974	Vertical value; LLK

Appearance energy determinations

Ion	AE (eV)	Other Products	Method	Reference	Comment
C₃H₃Ni⁺	16.7 ± 0.1	?	EI	Flesch, Junk, et al., 1972	LLK
C₃H₃Ni⁺	17.2 ± 0.2	?	EI	Muller and D'Or, 1967	RDSH
C₅H₅Ni⁺	12.6 ± 0.2	?	EI	Begun and Compton, 1973	LLK
C₅H₅Ni⁺	13.00 ± 0.25	C₅H₅	EI	Flesch, Junk, et al., 1972	LLK
C₅H₅Ni⁺	12.4	?	EI	Schissel, McAdoo, et al., 1968	RDSH
C₅H₅Ni⁺	12. ± 1.	?	EI	Pignataro and Lossing, 1967	RDSH
C₅H₅Ni⁺	12.6 ± 0.1	?	EI	Muller and D'Or, 1967	RDSH
C₈H₈Ni⁺	12.6 ± 0.1	C₂H₂	EI	Flesch, Junk, et al., 1972	LLK
C₈H₈Ni⁺	12.2 ± 0.1	?	EI	Muller and D'Or, 1967	RDSH
C₁₀H₁₀⁺	13.3 ± 0.5	Ni	EI	Flesch, Junk, et al., 1972	LLK
Ni⁺	13.9 ± 0.4	(C₅H₅)₂	EI	Begun and Compton, 1973	LLK
Ni⁺	13.00 ± 0.25	(C₅H₅)₂	EI	Flesch, Junk, et al., 1972	LLK
Ni⁺	13.6	?	EI	Schissel, McAdoo, et al., 1968	RDSH
Ni⁺	13.7 ± 0.2	?	EI	Muller and D'Or, 1967	RDSH

References

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

Martinho Simões
Martinho Simões, J.A., Private communication (see http://webbook.nist.gov/chemistry/om/). [all data]

Chipperfield, Sneyd, et al., 1979
Chipperfield, J.R.; Sneyd, J.C.R.; Webster, D.E., J. Organometal. Chem., 1979, 178, 177. [all data]

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

Pedley and Rylance, 1977
Pedley, J.B.; Rylance, J., Computer Analysed Thermochemical Data: Organic and Organometallic Compounds, University of Sussex, Brigton, 1977. [all data]

Wilkinson, Pauson, et al., 1954
Wilkinson, G.; Pauson, P.L.; Cotton, F.A., J. Am. Chem. Soc., 1954, 76, 1970. [all data]

Cox and Pilcher, 1970
Cox, J.D.; Pilcher, G., Thermochemistry of Organic and Organometallic Compounds in Academic Press, New York, 1970. [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]

Azokpota, Calvarin, et al., 1976
Azokpota, C.; Calvarin, G.; Pommier, C., Heat capacity of molecular compounds with order-disorder transition: nickelocene, Ni(C₅H₅)₂, and ferrocene, Fe(C₅H₅)₂, J. Chem. Thermodynam., 1976, 8, 283-287. [all data]

Torres-Gómez, Barreiro-Rodríguez, et al., 1988
Torres-Gómez, L.A.; Barreiro-Rodríguez, G.; Méndez- Ruíz, F., Thermochim. Acta, 1988, 124, 179. [all data]

Turnbull, 1967
Turnbull, A.G., Austral. J. Chem., 1967, 20, 2757. [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]

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]

Turnbull, 1967, 2
Turnbull, AG, Thermochemistry of biscyclopentsdienyl metal compounds, Aust. J. Chem., 1967, 20, 12, 2757-621, https://doi.org/10.1071/CH9672757 . [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]

Hunter and Lias, 1998
Hunter, E.P.; Lias, S.G., Evaluated Gas Phase Basicities and Proton Affinities of Molecules: An Update, J. Phys. Chem. Ref. Data, 1998, 27, 3, 413-656, https://doi.org/10.1063/1.556018 . [all data]

Ryan, Eyler, et al., 1992
Ryan, M.F.; Eyler, J.R.; Richardson, D.E., Adiabatic ionization energies, bond disruption enthalpies, and solvation free energies for gas-phase metallocenes and metallocenium ions, J. Am. Chem. Soc., 1992, 114, 8611. [all data]

Begun and Compton, 1973
Begun, G.M.; Compton, R.N., Electron impact ionization studies of ferrocene, cobaltocene, nickelocene, and magnesocene, J. Chem. Phys., 1973, 58, 2271. [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]

Flesch, Junk, et al., 1972
Flesch, G.D.; Junk, G.A.; Svec, H.J., Ionization efficiency data and fragmentation mechanisms for ferrocene, nickelocene, and ruthenocene, J. Chem. Soc. Dalton Trans., 1972, 1102. [all data]

Schissel, McAdoo, et al., 1968
Schissel, P.; McAdoo, D.J.; Hedaya, E.; McNeil, D.W., Flash vacuum pyrolysis. III. Formation and ionization of cyclopentadienyl, cyclopentadienyl nickel, and dihydrofulvalene (dicyclopentadienyl) derived from nickelocene, J. Chem. Phys., 1968, 49, 5061. [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]

Foffani, Pignataro, et al., 1967
Foffani, A.; Pignataro, S.; Distefano, G.; Innorta, G., Influence of the ligand donor ability on the ionization potentials and fragmentation patterns of transition metal nitrosyl complexes, J. Organometal. Chem., 1967, 7, 473. [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]

Pignataro and Lossing, 1967
Pignataro, S.; Lossing, F.P., Mass spectra and ionization potentials of C₆H₆CrC₆H₆ and C₆H₆Cr(CO)₃, J. Organometal. Chem., 1967, 10, 531. [all data]

Notes

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Symbols used in this document:

AE	Appearance energy
C_p,solid	Constant pressure heat capacity of solid
S°_{solid,1 bar}	Entropy of solid at standard conditions (1 bar)
T_trs	Temperature of phase transition
ΔH_trs	Enthalpy of phase transition
ΔS_trs	Entropy of phase transition
Δ_cH°_solid	Enthalpy of combustion of solid at standard conditions
Δ_fH°_gas	Enthalpy of formation of gas at standard conditions
Δ_fH°_solid	Enthalpy of formation of solid at standard conditions
Δ_subH°	Enthalpy of sublimation at standard conditions

Data from NIST Standard Reference Database 69: NIST Chemistry WebBook
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