Methylene, difluoro-
- Formula: CF2
- Molecular weight: 50.0075
- IUPAC Standard InChIKey: LTVOKYUPTHZZQH-UHFFFAOYSA-N
- CAS Registry Number: 2154-59-8
- Chemical structure:
This structure is also available as a 2d Mol file or as a computed 3d SD file
The 3d structure may be viewed using Java or Javascript. - Other names: Calcium difluoride; Difluoromethylene
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Reaction thermochemistry data
Go To: Top, Gas phase ion energetics data, Ion clustering data, References, Notes
Data compilation copyright by the U.S. Secretary of Commerce on behalf of the U.S.A. All rights reserved.
Data compiled by: John E. Bartmess
Note: Please consider using the reaction search for this species. This page allows searching of all reactions involving this species. A general reaction search form is also available. Future versions of this site may rely on reaction search pages in place of the enumerated reaction displays seen below.
Individual Reactions
By formula: (CF3- • 4294967295CF2) + CF2 = CF3-
Quantity | Value | Units | Method | Reference | Comment |
---|---|---|---|---|---|
ΔrH° | 49.8 ± 2.4 | kcal/mol | N/A | Deyerl, Alconcel, et al., 2001 | gas phase; Adiabatic EA, from vibrational structure of spectrum |
ΔrH° | 50.9 ± 2.9 | kcal/mol | N/A | Bartmess, Scott, et al., 1979 | gas phase; Paulino and Squires, 1991 suggests that this acidity may be too weak by ca. 5 kcal/mol. However, G2 calcn(JEB) give ΔHacid=379.9, ΔGacid=372.0; value altered from reference due to change in acidity scale |
ΔrH° | 55.9 ± 2.7 | kcal/mol | CIDT | Paulino and Squires, 1991 | gas phase; Neutral heat is based on a fluoroform acidity that may be too weak by up to 5 kcal/mol |
(CAS Reg. No. 53959-80-1 • 4294967295) + = CAS Reg. No. 53959-80-1
By formula: (CAS Reg. No. 53959-80-1 • 4294967295CF2) + CF2 = CAS Reg. No. 53959-80-1
Quantity | Value | Units | Method | Reference | Comment |
---|---|---|---|---|---|
ΔrH° | <8.00 | kcal/mol | CIDT | Paulino and Squires, 1991, 2 | gas phase; Probably CF2..Cl-, non-covalent. |
Gas phase ion energetics data
Go To: Top, Reaction thermochemistry data, Ion clustering data, References, Notes
Data compilation copyright by the U.S. Secretary of Commerce on behalf of the U.S.A. All rights reserved.
Data evaluated as indicated in comments:
HL - Edward P. Hunter and Sharon G. Lias
L - 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
B - John E. Bartmess
View reactions leading to CF2+ (ion structure unspecified)
Quantity | Value | Units | Method | Reference | Comment |
---|---|---|---|---|---|
IE (evaluated) | 11.44 ± 0.03 | eV | N/A | N/A | L |
Quantity | Value | Units | Method | Reference | Comment |
Proton affinity (review) | 183. | kcal/mol | N/A | Hunter and Lias, 1998 | HL |
Quantity | Value | Units | Method | Reference | Comment |
Gas basicity | 175.1 | kcal/mol | N/A | Hunter and Lias, 1998 | HL |
Electron affinity determinations
EA (eV) | Method | Reference | Comment |
---|---|---|---|
0.180 ± 0.020 | LPES | Schwartz, Davico, et al., 1999 | Neutral carbene triplet 54±3 kcal/mol above singlet; B |
0.1790 ± 0.0050 | LPES | Murray, Leopold, et al., 1988 | Singlet-triplet splitting in neutral > 50 kcal/mol; B |
0.07 ± 0.15 | D-EA | Born, Ingemann, et al., 1994 | B |
<1.30 ± 0.80 | EIAE | Harland and Thynne, 1972 | From C2F4. G3MP2B3 calculations indicate an EA of ca. 0.4 eV.; B |
>0.20047 | EIAE | Thynne and MacNeil, 1970 | From C2F4. G3MP2B3 calculations indicate an EA of ca. 0.4 eV.; B |
2.64955 | SI | Page and Goode, 1969 | The Magnetron method, lacking mass analysis, is not considered reliable.; B |
Ionization energy determinations
IE (eV) | Method | Reference | Comment |
---|---|---|---|
11.445 ± 0.025 | PI | Buckley, Johnson, et al., 1995 | LL |
15.2 | EI | Goto, Nakamura, et al., 1994 | LL |
11.5 ± 0.4 | EI | Tarnovsky and Becker, 1993 | LL |
11.4 ± 0.3 | EI | Hildenbrand, 1975 | LLK |
11.5 ± 0.1 | EI | Hildenbrand, 1975 | LLK |
11.42 ± 0.01 | PE | Dyke, Golob, et al., 1974 | LLK |
9.74 | DER | Reinke, Kraessig, et al., 1973 | LLK |
11.54 ± 0.10 | EI | Hildenbrand, 1973 | LLK |
11.7 ± 0.2 | EI | Ehlert, 1969 | RDSH |
11.8 ± 0.3 | EI | Zmbov, Uy, et al., 1968 | RDSH |
11.9 ± 0.1 | EI | Pottie, 1965 | RDSH |
11.7 ± 0.1 | EI | Fisher, Homer, et al., 1965 | RDSH |
Appearance energy determinations
Ion | AE (eV) | Other Products | Method | Reference | Comment |
---|---|---|---|---|---|
CF+ | 18.5 | F | EI | Goto, Nakamura, et al., 1994 | LL |
CF+ | 14.6 ± 0.4 | F | EI | Tarnovsky, Kurunczi, et al., 1993 | LL |
F+ | 31.4 ± 1.0 | CF+ | EI | Tarnovsky, Kurunczi, et al., 1993 | LL |
Ion clustering data
Go To: Top, Reaction thermochemistry data, Gas phase ion energetics data, References, Notes
Data compilation copyright by the U.S. Secretary of Commerce on behalf of the U.S.A. All rights reserved.
Data compiled by: John E. Bartmess
Note: Please consider using the reaction search for this species. This page allows searching of all reactions involving this species. Searches may be limited to ion clustering reactions. A general reaction search form is also available.
Clustering reactions
By formula: (CF3- • 4294967295CF2) + CF2 = CF3-
Quantity | Value | Units | Method | Reference | Comment |
---|---|---|---|---|---|
ΔrH° | 49.8 ± 2.4 | kcal/mol | N/A | Deyerl, Alconcel, et al., 2001 | gas phase; Adiabatic EA, from vibrational structure of spectrum |
ΔrH° | 50.9 ± 2.9 | kcal/mol | N/A | Bartmess, Scott, et al., 1979 | gas phase; Paulino and Squires, 1991 suggests that this acidity may be too weak by ca. 5 kcal/mol. However, G2 calcn(JEB) give ΔHacid=379.9, ΔGacid=372.0; value altered from reference due to change in acidity scale |
ΔrH° | 55.9 ± 2.7 | kcal/mol | CIDT | Paulino and Squires, 1991 | gas phase; Neutral heat is based on a fluoroform acidity that may be too weak by up to 5 kcal/mol |
References
Go To: Top, Reaction thermochemistry data, Gas phase ion energetics data, Ion clustering data, Notes
Data compilation copyright by the U.S. Secretary of Commerce on behalf of the U.S.A. All rights reserved.
Deyerl, Alconcel, et al., 2001
Deyerl, H.J.; Alconcel, L.S.; Continetti, R.E.,
Photodetachment imaging studies of the electron affinity of CF3,
J. Phys. Chem. A, 2001, 105, 3, 552-557, https://doi.org/10.1021/jp003137k
. [all data]
Bartmess, Scott, et al., 1979
Bartmess, J.E.; Scott, J.A.; McIver, R.T., Jr.,
The gas phase acidity scale from methanol to phenol,
J. Am. Chem. Soc., 1979, 101, 6047. [all data]
Paulino and Squires, 1991
Paulino, J.A.; Squires, R.R.,
Carbene Thermochemistry from Collision-Induced Dissociation Threshold Energy Measurements - The Heats of Formation of X1A1 CF2 and X1A1 CCl2,
J. Am. Chem. Soc., 1991, 113, 15, 5573, https://doi.org/10.1021/ja00015a009
. [all data]
Paulino and Squires, 1991, 2
Paulino, J.A.; Squires, R.R.,
Carbene Anion Complexes - Unusual Structural and Thermochemical Features of alpha-Halocarbanions in the Gas Phase,
J. Am. Chem. Soc., 1991, 113, 5, 1845, https://doi.org/10.1021/ja00005a067
. [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]
Schwartz, Davico, et al., 1999
Schwartz, R.L.; Davico, G.E.; Ramond, T.M.; Lineberger, W.C.,
Singlet-triplet splittings in CX2 (X = F, Cl, Br, I) dihalocarbenes via negative ion photoelectron spectroscopy,
J. Phys. Chem. A, 1999, 103, 41, 8213-8221, https://doi.org/10.1021/jp992214c
. [all data]
Murray, Leopold, et al., 1988
Murray, K.K.; Leopold, D.G.; Miller, T.M.; Lineberger, W.C.,
Photoelectron Spectroscopy of the Halocarbene Anions HCF-, HCCl-, HCBr-, HCI-, CF2-, and CCl2-,
J. Chem. Phys., 1988, 89, 9, 5442, https://doi.org/10.1063/1.455596
. [all data]
Born, Ingemann, et al., 1994
Born, M.; Ingemann, S.; Nibbering, N.M.M.,
Heats of formation of mono-halogen-substituted carbenes. Stability and reactivity of CHX(center dot-) (X=F, Cl, Pr, and I) radical anions,
J. Am. Chem. Soc., 1994, 116, 16, 7210, https://doi.org/10.1021/ja00095a025
. [all data]
Harland and Thynne, 1972
Harland, P.W.; Thynne, J.C.J.,
Ionisation of perfluorocyclobutane by electron impact,
Int. J. Mass Spectrom. Ion Phys., 1972, 10, 11. [all data]
Thynne and MacNeil, 1970
Thynne, J.C.J.; MacNeil, K.A.G.,
Ionisation of Tetrafluoroethylene by Electron Impact,
Int. J. Mass Spectrom. Ion Phys., 1970, 5, 3-4, 329, https://doi.org/10.1016/0020-7381(70)80026-2
. [all data]
Page and Goode, 1969
Page, F.M.; Goode, G.C.,
Negative Ions and the Magnetron., Wiley, NY, 1969. [all data]
Buckley, Johnson, et al., 1995
Buckley, T.J.; Johnson, R.D.; Huie, R.E.; Zhang, Z.; Kuo, S.C.; Klemm, R.B.,
Ionization energies, appearance energies, and thermochemistry of CF2O and FCO,
J. Phys. Chem., 1995, 99, 4879. [all data]
Goto, Nakamura, et al., 1994
Goto, M.; Nakamura, K.; Toyoda, H.; Sugai, H.,
Cross section measurements for electron-impact dissociation of CHF3 into neutral and ionic fragments,
Jpn. J. Appl. Phys. Part 1, 1994, 33, 3602. [all data]
Tarnovsky and Becker, 1993
Tarnovsky, V.; Becker, K.,
Absolute partial cross sections for the parent ionization of the CFx (x = 1-3) free radicals by electron impact,
J. Chem. Phys., 1993, 98, 7868. [all data]
Hildenbrand, 1975
Hildenbrand, D.L.,
Vertical ionization potential of the CF2 radical,
Chem. Phys. Lett., 1975, 32, 30. [all data]
Dyke, Golob, et al., 1974
Dyke, J.M.; Golob, L.; Jonathan, N.; Morris, A.; Okuda, M.,
Vacuum ultraviolet photoelectron spectroscopy of transient species. Part 4. Difluoromethylene and ozone,
J. Chem. Soc. Faraday Trans. 2, 1974, 70, 1828. [all data]
Reinke, Kraessig, et al., 1973
Reinke, D.; Kraessig, R.; Baumgartel, H.,
Photoreactions of small organic molecules,
Z. Naturforsch. A:, 1973, 28, 1021. [all data]
Hildenbrand, 1973
Hildenbrand, D.L.,
Mass spectrometric studies of some gaseous sulfur fluorides,
J. Phys. Chem., 1973, 77, 897. [all data]
Ehlert, 1969
Ehlert, T.C.,
Bonding in C1 and C2 fluorides,
J. Phys. Chem., 1969, 73, 949. [all data]
Zmbov, Uy, et al., 1968
Zmbov, K.F.; Uy, M.; Margrave, J.L.,
Mass spectrometric study of the high-temperature equilibrium C2F4 = 2CF2 and the heat of formation of the CF2 radical,
J. Am. Chem. Soc., 1968, 90, 5090. [all data]
Pottie, 1965
Pottie, R.F.,
Ionization potential and heat of formation of the difluoromethylene radical,
J. Chem. Phys., 1965, 42, 2607. [all data]
Fisher, Homer, et al., 1965
Fisher, I.P.; Homer, J.B.; Lossing, F.P.,
Free radicals by mass spectrometry. XXXIII. Ionization potentials of CF2, CF3CF2, CF3CH2, n-C3F7, and i-C3F7 radicals,
J. Am. Chem. Soc., 1965, 87, 957. [all data]
Tarnovsky, Kurunczi, et al., 1993
Tarnovsky, V.; Kurunczi, P.; Rogozhnikov, D.; Becker, K.,
Absolute cross sections for the dissociative electron impact ionization of the CFx (x=1-3) free radicals,
Int. J. Mass Spectrom. Ion Processes, 1993, 128, 181. [all data]
Notes
Go To: Top, Reaction thermochemistry data, Gas phase ion energetics data, Ion clustering data, References
- Symbols used in this document:
AE Appearance energy EA Electron affinity IE (evaluated) Recommended ionization energy ΔrH° Enthalpy of reaction at standard conditions - Data from NIST Standard Reference Database 69: NIST Chemistry WebBook
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