Silyl radical

Formula: H₃Si
Molecular weight: 31.1093
IUPAC Standard InChI: InChI=1S/H3Si/h1H3
IUPAC Standard InChIKey: OLRJXMHANKMLTD-UHFFFAOYSA-N
CAS Registry Number: 13765-44-1
Chemical structure:
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Reaction thermochemistry data

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Data compiled by: John E. Bartmess

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Individual Reactions

H₂Si^- + = Silyl radical

By formula: H₂Si^- + H⁺ = H₃Si

Quantity	Value	Units	Method	Reference	Comment
Δ_rH°	357.2 ± 1.4	kcal/mol	D-EA	Kasdan, Herbst, et al., 1975	gas phase

Gas phase ion energetics data

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Data evaluated as indicated in comments:
L - Sharon G. Lias

Data compiled as indicated in comments:
B - John E. Bartmess
LL - Sharon G. Lias and Joel F. Liebman
LBLHLM - Sharon G. Lias, John E. Bartmess, Joel F. Liebman, John L. Holmes, Rhoda D. Levin, and W. Gary Mallard

View reactions leading to H₃Si⁺ (ion structure unspecified)

Quantity	Value	Units	Method	Reference	Comment
IE (evaluated)	8.135 ± 0.005	eV	N/A	N/A	L
Quantity	Value	Units	Method	Reference	Comment
Δ_fH°_{(+) ion}	235.5 ± 0.7	kcal/mol	N/A	N/A
Quantity	Value	Units	Method	Reference	Comment
Δ_fH_{(+) ion,0K}	237. ± 1.	kcal/mol	N/A	N/A

Electron affinity determinations

EA (eV)	Method	Reference	Comment
1.405 ± 0.026	LPD	Wetzel, Salomon, et al., 1989	B
1.406 ± 0.014	LPES	Nimlos and Ellison, 1986	B
1.440 ± 0.097	D-EA	Bartmess, Scott, et al., 1979	value altered from reference due to change in acidity scale; B
<1.440 ± 0.030	LPD	Reed and Brauman, 1974	B
1.35734	N/A	Check, Faust, et al., 2001	MnS-(t); ; ΔS(EA)=5.7; B

Ionization energy determinations

IE (eV)	Method	Reference	Comment
8.17	DER	Nagano, Murthy, et al., 1993	LL
8.135 ± 0.005	LS	Johnson III, Tsai, et al., 1989	T = 0K; LL
8.11 ± 0.07	END	Boo and Armentrout, 1987	LBLHLM
8.01 ± 0.02	PI	Berkowitz, Greene, et al., 1987	LBLHLM
8.31 ± 0.07	PI	Ding, Cassidy, et al., 1985	LBLHLM
8.14 ± 0.01	PE	Dyke, Jonathan, et al., 1983	LBLHLM
8.74 ± 0.01	PE	Dyke, Jonathan, et al., 1983	Vertical value; LBLHLM

De-protonation reactions

H₂Si^- + = Silyl radical

By formula: H₂Si^- + H⁺ = H₃Si

Quantity	Value	Units	Method	Reference	Comment
Δ_rH°	357.2 ± 1.4	kcal/mol	D-EA	Kasdan, Herbst, et al., 1975	gas phase; B

Vibrational and/or electronic energy levels

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Data compiled by: Marilyn E. Jacox

State: M

Energy (cm^-1)	Med.	Transition	References


T_o = 60341	gas	M-X	Johnson III, Tsai, et al., 1989

Vib. sym.	No.	Approximate type of mode	cm^-1	Med.	Method	References


a₂	2	OPLA	800 ± 30	gas	MPI	Johnson III, Tsai, et al., 1989

State: L

Energy (cm^-1)	Med.	Transition	References


T_o = 59615 ± 30	gas	L-X	Johnson and Hudgens, 1991

Vib. sym.	No.	Approximate type of mode	cm^-1	Med.	Method	References


a₂	2	OPLA	839 ± 26	gas	MPI	Johnson and Hudgens, 1991

State: J'

Energy (cm^-1)	Med.	Transition	References


T_o = 57726 ± 30	gas	J'-X	Johnson and Hudgens, 1991

Vib. sym.	No.	Approximate type of mode	cm^-1	Med.	Method	References


a₂	2	OPLA	835 ± 26	gas	MPI	Johnson and Hudgens, 1991

State: J

Energy (cm^-1)	Med.	Transition	References


T_o = 56929	gas	J-X	Johnson III, Tsai, et al., 1989

Vib. sym.	No.	Approximate type of mode	cm^-1	Med.	Method	References


a₂	2	OPLA	821 ± 4	gas	MPI	Johnson III, Tsai, et al., 1989

State: I'

Energy (cm^-1)	Med.	Transition	References


T_o = 56253 ± 30	gas	I'-X	Johnson and Hudgens, 1991

Vib. sym.	No.	Approximate type of mode	cm^-1	Med.	Method	References


a₂	2	OPLA	814 ± 25	gas	MPI	Johnson and Hudgens, 1991

State: E

Energy (cm^-1)	Med.	Transition	References


T_o = 48438	gas	E-X	Johnson and Hudgens, 1987
			Johnson III, Tsai, et al., 1989

Vib. sym.	No.	Approximate type of mode	cm^-1		Med.	Method	References


a₂	2	OPLA	796 ± 7		gas	MPI	Johnson and Hudgens, 1987 Johnson III, Tsai, et al., 1989
e'	4	Deformation	870 ± 5	H	gas	MPI	Johnson III, Tsai, et al., 1989

State: D

Energy (cm^-1)	Med.	Transition	References


T_o = 49787 ± 30	gas	D-X	Johnson and Hudgens, 1991

Vib. sym.	No.	Approximate type of mode	cm^-1	Med.	Method	References


a₂	2	OPLA	810 ± 31	gas	MPI	Johnson and Hudgens, 1991

State: A

Med.	Transition	λ_min (nm)	λ_max (nm)	References


gas	A-X	205	256	Lightfoot, Becerra, et al., 1991
				Baklanov and Krasnoperov, 2001

State: X

Vib. sym.	No.	Approximate type of mode	cm^-1		Med.	Method	References


a₁	2	Umbrella	727.94	I	gas	DL MPI	Yamada and Hirota, 1986 Itabashi, Kato, et al., 1988 Johnson III, Tsai, et al., 1989
	2	Umbrella	721.05	I	gas	DL MPI	Yamada and Hirota, 1986 Itabashi, Kato, et al., 1988 Johnson III, Tsai, et al., 1989
	2	Umbrella	735.4		Ne	IR	Andrews and Wang, 2002
	2	Umbrella	727.3		Ne	IR	Andrews and Wang, 2002
	2	Umbrella	727.2		Ar	IR	Li, Graham, et al., 2001 Andrews and Wang, 2002
	2	Umbrella	732.4		Kr	IR	Legay-Sommaire and Legay, 1998
	2	Umbrella	730.0		Kr	IR	Legay-Sommaire and Legay, 1998
	2	Umbrella	722.9		H₂	IR	Wang and Andrews, 2003
e	3	SiH₃ stretch	2185.2		gas	DL	Sumiyoshi, Tanaka, et al., 1994
	4	Deformation	928.6		Ne	IR	Andrews and Wang, 2002
	4	Deformation	925.0		Ar	IR	Andrews and Wang, 2002
	4	Deformation	929		Kr	IR	Legay-Sommaire and Legay, 1998
	4	Deformation	925.3		H₂	IR	Wang and Andrews, 2003

Additional references: Jacox, 1994, page 126; Jacox, 1998, page 215; Jacox, 2003, page 158; Morehouse, Christiansen, et al., 1966; Jackel and Gordy, 1968; Nimlos and Ellison, 1986

Notes

(1/2)(2ν)

Component of an inversion doublet

Energy separation between the v = 0 levels of the excited and electronic ground states.

References

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Kasdan, Herbst, et al., 1975
Kasdan, A.; Herbst, E.; Lineberger, W.C., Laser photoelectron spectrometry of the negative ions of silicon and its hydrides, J. Chem. Phys., 1975, 62, 541. [all data]

Wetzel, Salomon, et al., 1989
Wetzel, D.M.; Salomon, K.E.; Berger, S.; Brauman, J.I., Gas-Phase Acidities of Organosilanes and Electron Affinities of Organosilyl Radicals, J. Am. Chem. Soc., 1989, 111, 11, 3835, https://doi.org/10.1021/ja00193a013 . [all data]

Nimlos and Ellison, 1986
Nimlos, M.R.; Ellison, G.B., Photoelectron spectroscopy of SiH₃^- and SiD₃^-, J. Am. Chem. Soc., 1986, 108, 6522. [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]

Reed and Brauman, 1974
Reed, K.J.; Brauman, J.I., Photodetachment of electrons from Group IVa binary hydride anions: The electron affinities of the SiH₃ and GeH₃ radicals, J. Chem. Phys., 1974, 61, 4830. [all data]

Check, Faust, et al., 2001
Check, C.E.; Faust, T.O.; Bailey, J.M.; Wright, B.J.; Gilbert, T.M.; Sunderlin, L.S., Addition of Polarization and Diffuse Functions to the LANL2DZ Basis Set for P-Block Elements, J. Phys. Chem. A,, 2001, 105, 34, 8111, https://doi.org/10.1021/jp011945l . [all data]

Nagano, Murthy, et al., 1993
Nagano, Y.; Murthy, S.; Beauchamp, J.L., Thermochemical properties and gas-phase ion chemistry of phenylsilane investigated by FT-ICR spectrometry. Identification of parent- and fragment-ion structural isomers by their specific reactivities, J. Am. Chem. Soc., 1993, 115, 10805. [all data]

Johnson III, Tsai, et al., 1989
Johnson III, R.D.; Tsai, B.P.; Hudgens, J.W., Multiphoton ionization of SiH₃ and SID₃ radicals: Electronic spectra, vibrational analyses of the ground and Rydberg states, and ionization potentials, J. Chem. Phys., 1989, 91, 3340. [all data]

Boo and Armentrout, 1987
Boo, B.H.; Armentrout, P.B., Reaction of silicon ion (2P) with silane (SiH₄, SiD₄) heats of formation of SiHn, SiHn⁺ (n=1,2,3), and Si₂Hn⁺ (n=0,1,2,3) remarkable isotope exchange reaction involving four hydrogen shifts, J. Am. Chem. Soc., 1987, 109, 3549. [all data]

Berkowitz, Greene, et al., 1987
Berkowitz, J.; Greene, J.P.; Cho, H.; Ruscic, B., Photoionization mass spectrometric studies of SiH_n (n=1-4), J. Chem. Phys., 1987, 86, 1235. [all data]

Ding, Cassidy, et al., 1985
Ding, A.; Cassidy, R.; Cordis, L.; Lampe, F., The photoionization spectra of effusing and supersonic molecular beams of Mmnosilane, J. Chem. Phys., 1985, 83, 3426. [all data]

Dyke, Jonathan, et al., 1983
Dyke, J.M.; Jonathan, N.; Morris, A.; Ridha, A.; Winter, M.J., Vacuum ultraviolet photoelectron spectroscopy of transient species. XVII. The SiH₃ (X2A1) radical, Chem. Phys., 1983, 81, 481. [all data]

Johnson and Hudgens, 1991
Johnson, R.D., III; Hudgens, J.W., Multiphoton ionization of SiH3 and SiD3 radicals. II. Three-photon resonance-enhanced spectra observed between 450 and 610 nm, J. Chem. Phys., 1991, 94, 8, 5331, https://doi.org/10.1063/1.460518 . [all data]

Johnson and Hudgens, 1987
Johnson, R.D., III; Hudgens, J.W., A new eletronic spectrum of the SiH3 radical observed using multiphoton ionization spectroscopy, Chem. Phys. Lett., 1987, 141, 3, 163, https://doi.org/10.1016/0009-2614(87)85002-9 . [all data]

Lightfoot, Becerra, et al., 1991
Lightfoot, P.D.; Becerra, R.; Jemi-Alade, A.A.; Lesclaux, R., The UV absorption spectrum of SiH3, Chem. Phys. Lett., 1991, 180, 5, 441, https://doi.org/10.1016/0009-2614(91)85146-N . [all data]

Baklanov and Krasnoperov, 2001
Baklanov, A.V.; Krasnoperov, L.N., UV Absorption Spectrum and Rate Constant for Self-Reaction of Silyl Radicals, J. Phys. Chem. A, 2001, 105, 20, 4917, https://doi.org/10.1021/jp004198l . [all data]

Yamada and Hirota, 1986
Yamada, C.; Hirota, E., Detection of the Silyl Radical SiH_{3} by Infrared Diode-Laser Spectroscopy, Phys. Rev. Lett., 1986, 56, 9, 923, https://doi.org/10.1103/PhysRevLett.56.923 . [all data]

Itabashi, Kato, et al., 1988
Itabashi, N.; Kato, K.; Nishiwaki, N.; Goto, T.; Yamada, C.; Hirota, E., Measurement of the SiH, Jap. J. Appl. Phys., 1988, 27, Part 2, No. 8, L1565, https://doi.org/10.1143/JJAP.27.L1565 . [all data]

Andrews and Wang, 2002
Andrews, L.; Wang, X., Infrared Spectra of the Novel Si, J. Phys. Chem. A, 2002, 106, 34, 7696, https://doi.org/10.1021/jp0204814 . [all data]

Li, Graham, et al., 2001
Li, L.; Graham, J.T.; Weltner, W., Jr., Infrared Spectra of Silane in Solid Argon and Hydrogen, J. Phys. Chem. A, 2001, 105, 49, 11018, https://doi.org/10.1021/jp013003m . [all data]

Legay-Sommaire and Legay, 1998
Legay-Sommaire, N.; Legay, F., Photochemical Insertion Reaction of Hg in SiH, J. Phys. Chem. A, 1998, 102, 45, 8759, https://doi.org/10.1021/jp9821533 . [all data]

Wang and Andrews, 2003
Wang, X.; Andrews, L., Infrared Spectra of Group 14 Hydrides in Solid Hydrogen: Experimental Observation of PbH, J. Am. Chem. Soc., 2003, 125, 21, 6581, https://doi.org/10.1021/ja029862l . [all data]

Sumiyoshi, Tanaka, et al., 1994
Sumiyoshi, Y.; Tanaka, K.; Tanaka, T., Diode laser spectroscopy of SiH3 in the 4.5 μm region, Appl. Surf. Sci., 1994, 79/80, 471, https://doi.org/10.1016/0169-4332(94)90457-X . [all data]

Jacox, 1994
Jacox, M.E., Vibrational and electronic energy levels of polyatomic transient molecules, American Chemical Society, Washington, DC, 1994, 464. [all data]

Jacox, 1998
Jacox, M.E., Vibrational and electronic energy levels of polyatomic transient molecules: supplement A, J. Phys. Chem. Ref. Data, 1998, 27, 2, 115-393, https://doi.org/10.1063/1.556017 . [all data]

Jacox, 2003
Jacox, M.E., Vibrational and electronic energy levels of polyatomic transient molecules: supplement B, J. Phys. Chem. Ref. Data, 2003, 32, 1, 1-441, https://doi.org/10.1063/1.1497629 . [all data]

Morehouse, Christiansen, et al., 1966
Morehouse, R.L.; Christiansen, J.J.; Gordy, W., ESR of Free Radicals Trapped in Inert Matrices at Low Temperature: CH3, SiH3, GeH3, and SnH3, J. Chem. Phys., 1966, 45, 5, 1751, https://doi.org/10.1063/1.1727825 . [all data]

Jackel and Gordy, 1968
Jackel, G.S.; Gordy, W., Electron Spin Resonance of Free Radicals Formed from Group-IV and Group-V Hydrides in Inert Matrices at Low Temperature, Phys. Rev., 1968, 176, 2, 443, https://doi.org/10.1103/PhysRev.176.443 . [all data]

Notes

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Symbols used in this document:

EA Electron affinity

IE (evaluated) Recommended ionization energy

Δ_fH_{(+) ion,0K} Enthalpy of formation of positive ion at 0K

Δ_rH° Enthalpy of reaction at standard conditions
Data from NIST Standard Reference Database 69: NIST Chemistry WebBook
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EA	Electron affinity
IE (evaluated)	Recommended ionization energy
Δ_fH_{(+) ion,0K}	Enthalpy of formation of positive ion at 0K
Δ_rH°	Enthalpy of reaction at standard conditions