Silylidyne

Formula: HSi
Molecular weight: 29.0934
IUPAC Standard InChI: InChI=1S/HSi/h1H
IUPAC Standard InChIKey: QHGSGZLLHBKSAH-UHFFFAOYSA-N
CAS Registry Number: 13774-94-2
Chemical structure:
This structure is also available as a 2d Mol file or as a computed 3d SD file
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Other data available:
- Reaction thermochemistry data
- Ion clustering data
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Gas phase thermochemistry data

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Quantity	Value	Units	Method	Reference	Comment
Δ_fH°_gas	90.024	kcal/mol	Review	Chase, 1998	Data last reviewed in December, 1976
Quantity	Value	Units	Method	Reference	Comment
S°_{gas,1 bar}	47.333	cal/mol*K	Review	Chase, 1998	Data last reviewed in December, 1976

Gas Phase Heat Capacity (Shomate Equation)

C_p° = A + B*t + C*t² + D*t³ + E/t²
H° − H°_298.15= A*t + B*t²/2 + C*t³/3 + D*t⁴/4 − E/t + F − H
S° = A*ln(t) + B*t + C*t²/2 + D*t³/3 − E/(2*t²) + G
C_p = heat capacity (cal/mol*K)
H° = standard enthalpy (kcal/mol)
S° = standard entropy (cal/mol*K)
t = temperature (K) / 1000.

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View table.

Temperature (K)	298. to 1400.	1400. to 6000.
A	5.628892	9.030290
B	3.206100	0.058574
C	-0.645540	-0.002209
D	-0.123228	0.004993
E	0.059737	-1.137600
F	88.41030	85.16511
G	53.55559	55.76370
H	90.02450	90.02450
Reference	Chase, 1998	Chase, 1998
Comment	Data last reviewed in December, 1976	Data last reviewed in December, 1976

Gas phase ion energetics data

Go To: Top, Gas phase thermochemistry data, Constants of diatomic molecules, References, Notes

Data compiled as indicated in comments:
B - John E. Bartmess
LBLHLM - Sharon G. Lias, John E. Bartmess, Joel F. Liebman, John L. Holmes, Rhoda D. Levin, and W. Gary Mallard
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 HSi⁺ (ion structure unspecified)

Electron affinity determinations

EA (eV)	Method	Reference	Comment
1.2771 ± 0.0087	LPES	Kasdan, Herbst, et al., 1975	B

Ionization energy determinations

IE (eV)	Method	Reference	Comment
7.89 ± 0.07	END	Boo and Armentrout, 1987	LBLHLM
7.91 ± 0.01	PI	Berkowitz, Greene, et al., 1987	LBLHLM
8.27 ± 0.06	S	Carslon, Copley, et al., 1980	LLK
8.04	DER	Huber and Herzberg, 1979	LLK
7.91	S	Rao and Lakshman, 1971	LLK
8.01 ± 0.08	DER	Douglas and Lutz, 1970	RDSH

De-protonation reactions

Si^- + = Silylidyne

By formula: Si^- + H⁺ = HSi

Quantity	Value	Units	Method	Reference	Comment
Δ_rH°	353.1 ± 2.7	kcal/mol	D-EA	Blondel, Chaibi, et al., 2005	gas phase; (28)Si: 1.3895213(13) eV; revised analysis of Blondel, Delsart, et al., 2001; B
Quantity	Value	Units	Method	Reference	Comment
Δ_rG°	347.9 ± 2.8	kcal/mol	H-TS	Blondel, Chaibi, et al., 2005	gas phase; (28)Si: 1.3895213(13) eV; revised analysis of Blondel, Delsart, et al., 2001; B

Constants of diatomic molecules

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

Data compiled by: Klaus P. Huber and Gerhard H. Herzberg

Data collected through August, 1977

Symbols used in the table of constants
Symbol	Meaning
State	electronic state and / or symmetry symbol
T_e	minimum electronic energy (cm^-1)
ω_e	vibrational constant – first term (cm^-1)
ω_ex_e	vibrational constant – second term (cm^-1)
ω_ey_e	vibrational constant – third term (cm^-1)
B_e	rotational constant in equilibrium position (cm^-1)
α_e	rotational constant – first term (cm^-1)
γ_e	rotation-vibration interaction constant (cm^-1)
D_e	centrifugal distortion constant (cm^-1)
β_e	rotational constant – first term, centrifugal force (cm^-1)
r_e	internuclear distance (Å)
Trans.	observed transition(s) corresponding to electronic state
ν₀₀	position of 0-0 band (units noted in table)

Diatomic constants for ²⁸SiH
State	T_e	ω_e	ω_ex_e	ω_ey_e	B_e	α_e	γ_e	D_e	β_e	r_e	Trans.	ν₀₀
E ²Σ⁺	[53411.2] 1				[7.528]			[3.92E-4]		[1.517₂]	E ← X V	52399.19 Z
E ²Σ⁺	↳missing citation
D ²Δ	[49522.1] 1				[7.90] 2					[1.48₁]	D ← X V	48510.1 Z
D ²Δ	↳Verma, 1965; missing citation
B ²Σ⁺	[31842.2] 1				[6.62] 3 4					[1.61₈]	B ← X R	30830.2 3 Z
B ²Σ⁺	↳missing citation; Bollmark, Klynning, et al., 1971
C ²Σ⁺	[31832.4] 5				[1.17] 3					[3.8₅]	C ← X R	30820.4 3 Z
C ²Σ⁺	↳Verma, 1965; Bollmark, Klynning, et al., 1971
"Slightly diffuse" weak absorption bands in the region 25600 - 26700 cm^-1.
↳Thrush, 1960
State	T_e	ω_e	ω_ex_e	ω_ey_e	B_e	α_e	γ_e	D_e	β_e	r_e	Trans.	ν₀₀
A ²Δ	24300.4 6	1858.90 7 Z	99.17₅		7.4664 7	0.3445	-0.0418₅	[5.24E-4] 8		1.5234₇	A ↔ X 9 10 R	24193.04 Z
A ²Δ	↳missing citation; Douglas, 1957; missing citation; Klynning and Lindgren, 1967; Herzberg, Lagerqvist, et al., 1969
X ²Π_r	0 11	2041.80 7 Z	35.51		7.4996 7 12	0.2190	0.0017	[3.97E-4]		1.5201₀ 13

Notes

Only v=0 observed

Increasing diffuseness with increasing N on account of predissociation.

Deperturbed constants of Bollmark, Klynning, et al., 1971 whose T₀ values correspond to ν₀₀ + 1079.5 [see Klynning and Lindgren, 1967]. As in similar cases, ν₀₀ refers to the zero-point of the Hill-VanVleck expression for the ground state. Interaction parameter H_B,C = 16.1 cm^-1. The v numbering of the C level is uncertain.

Strongly predissociated above N=2.

Only one level observed

A₀ = 3.58 Klynning and Lindgren, 1967, A₁ = 3.11 Klynning and Lindgren, 1967, A₂ = 2.59 Klynning and Lindgren, 1967. Discussion of second order spin-orbit splittings Veseth, 1971.

Recalculated Herzberg, Lagerqvist, et al., 1969 from data for v=0, 1, 2 Klynning and Lindgren, 1967.

missing note

Smith, 1969 gives a radiative lifetime of 0.7 μs for both SiH and SiD corresponding to f₀₀ = 0.0037 Smith and Liszt, 1971; see also Grevesse and Sauval, 1971.

Potential functions, Franck-Condon factors Rao and Lakshman, 1971, Smith and Liszt, 1971

A₀ = +142.83. A₁ = +143.43. A₂ = +144.04. Slight J dependence Klynning and Lindgren, 1967.

For Λ-doubling constants (p₀ = 0.0819, q₀ = 0.00831) see Klynning and Lindgren, 1967, missing citation; the extrapolated splitting of the v=0, J=1/2 level is Δ v_fe = +0.0978 cm^-1 (2932 ± 20 MHz) missing citation; ab initio calculations Wilson and Richards, 1975 predict Δ v_fe= 0.1057 cm^-1 (3168 MHz).

Extensive theoretical calculations 17

From the predissociation in B ²Σ⁺ assuming dissociation into ¹D + ²S at the predissociation limit Verma, 1965. According to Douglas, 1957 extrapolation of the vibrational levels in A ²Δ gives very nearly the same limit.

From D₀⁰(SiH), I.P.(Si), and D₀⁰(SiH⁺) Douglas and Lutz, 1970.

D₁ = 6.08E-4, D₂ = 7.36E-4.

Hartree-Fock wavefunctions and energies Cade and Huo, 1967, charge distributions Cade, Bader, et al., 1969, spectroscopic constants Meyer and Rosmus, 1975.

From the value for SiH, confirmed by the observed predissociation in B 2Σ⁺.

Recalculated from the data of Verma, 1965.

Deperturbed constants of Bollmark, Klynning, et al., 1971 whose T₀ values correspond to ν₀₀ + 797.50 [see Klynning and Lindgren, 1967]. Interaction parameter H_B,C = 5.87 cm^-1. See 3.

Increasing linewidth above N=8 indicating predissociation.

A₀ = 3.45, A₁ = 3.42, A₂ = 2.14 Klynning and Lindgren, 1967; see also Veseth, 1971.

D₁ = 1.524E-4, D₂ = 1.708E-4.

A₀ = +142.73, A₁ = +143.10; A₂= +143.76; slight J dependence Klynning and Lindgren, 1967.

Klynning and Lindgren, 1967 give Λ-doubling constants (p= 0.039, q= 0.0024).

References

Go To: Top, Gas phase thermochemistry data, Gas phase ion energetics data, Constants of diatomic molecules, Notes

Chase, 1998
Chase, M.W., Jr., NIST-JANAF Themochemical Tables, Fourth Edition, J. Phys. Chem. Ref. Data, Monograph 9, 1998, 1-1951. [all data]

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]

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]

Carslon, Copley, et al., 1980
Carslon, T.A.; Copley, J.; Duric, N.; Perman, N. -Elander; Larsson, M.; Lyyra, M., The oscillator strengths and the dissociation energy of SiH⁺ as determined from time resolved precision spectroscopy, Astron. Astrophys., 1980, 83, 238. [all data]

Huber and Herzberg, 1979
Huber, K.P.; Herzberg, G., Molecular Spectra and Molecular Structure. IV. Constants of Diatomic Molecules,, Van Nostrand Reinhold Co., 1979, ,1. [all data]

Rao and Lakshman, 1971
Rao, T.V.R.; Lakshman, S.V.J., The true potential energy curves and Franck-Condon factors of SiH and SiH⁺ molecules, Physica, 1971, 56, 322. [all data]

Douglas and Lutz, 1970
Douglas, A.E.; Lutz, B.L., Spectroscopic identification of the SiH⁺ molecule: the A 1π-X1⁺ system, Can. J. Phys., 1970, 48, 247. [all data]

Blondel, Chaibi, et al., 2005
Blondel, C.; Chaibi, W.; Delsart, C.; Drag, C.; Goldfarb, F.; Kroger, S., The electron affinities of O, Si, and S revisited with the photodetachment microscope, Eur. Phys. J. D, 2005, 33, 3, 335-342, https://doi.org/10.1140/epjd/e2005-00069-9 . [all data]

Blondel, Delsart, et al., 2001
Blondel, C.; Delsart, C.; Goldfarb, F., Electron spectrometry at the mu eV level and the electron affinities of Si and F, J. Phys. B: Atom. Mol. Opt. Phys., 2001, 34, 9, L281-L288, https://doi.org/10.1088/0953-4075/34/9/101 . [all data]

Verma, 1965
Verma, R.D., The spectrum of SiH and SiD, Can. J. Phys., 1965, 43, 2136. [all data]

Bollmark, Klynning, et al., 1971
Bollmark, P.; Klynning, L.; Pages, P., Rotational analysis of the 3250 Å bands of SiH and SiD, Phys. Scr., 1971, 3, 219-222. [all data]

Thrush, 1960
Thrush, B.A., Absorption spectra of diatomic radicals containing boron or silicon, Nature (London), 1960, 186, 1044. [all data]

Douglas, 1957
Douglas, A.E., The spectrum of silicon hydride, Can. J. Phys., 1957, 35, 71. [all data]

Klynning and Lindgren, 1967
Klynning, L.; Lindgren, B., The spectra of silicon hydride and silicon deuteride, Ark. Fys., 1967, 33, 73. [all data]

Herzberg, Lagerqvist, et al., 1969
Herzberg, G.; Lagerqvist, A.; McKenzie, B.J., Absorption spectrum of SiH in the vacuum ultraviolet, Can. J. Phys., 1969, 47, 1889. [all data]

Veseth, 1971
Veseth, L., Second-order spin-orbit splitting in ²Δ states of diatomic molecules, Physica (Amsterdam), 1971, 56, 286. [all data]

Smith, 1969
Smith, W.H., Lifetimes and total transition probabilities for NH, SiH, and SiD, J. Chem. Phys., 1969, 51, 520. [all data]

Smith and Liszt, 1971
Smith, W.H.; Liszt, H.S., Franck-Condon factors and absolute oscillator strengths for NH, SiH, S₂ and SO, J. Quant. Spectrosc. Radiat. Transfer, 1971, 11, 45. [all data]

Grevesse and Sauval, 1971
Grevesse, N.; Sauval, A.J., Oscillator strengths for SiH and SiH⁺ deduced from the solar spectrum, J. Quant. Spectrosc. Radiat. Transfer, 1971, 11, 65. [all data]

Wilson and Richards, 1975
Wilson, I.D.L.; Richards, W.G., Λ-type doubling in SiH molecule, Nature (London), 1975, 258, 133. [all data]

Cade and Huo, 1967
Cade, P.E.; Huo, W.M., Electronic structure of diatomic molecules. VII.A. Hartree-Fock wavefunctions and energy quantities for the ground states of the second-row hydrides, AH, J. Chem. Phys., 1967, 47, 649. [all data]

Cade, Bader, et al., 1969
Cade, P.E.; Bader, R.F.W.; Henneker, W.H.; Keaveny, I., Molecular charge distributions and chemical binding. IV. The second-row diatomic hydrides AH, J. Chem. Phys., 1969, 50, 5313. [all data]

Meyer and Rosmus, 1975
Meyer, W.; Rosmus, P., PNO-Cl and CEPA studies of electron correlation effects. III. Spectroscopic constants and dipole moment functions for the ground states of the first-row and second-row diatomic hydrides, J. Chem. Phys., 1975, 63, 2356. [all data]

Notes

Go To: Top, Gas phase thermochemistry data, Gas phase ion energetics data, Constants of diatomic molecules, References

Symbols used in this document:

EA	Electron affinity
S°_{gas,1 bar}	Entropy of gas at standard conditions (1 bar)
Δ_fH°_gas	Enthalpy of formation of gas at standard conditions
Δ_rG°	Free energy of reaction at standard conditions
Δ_rH°	Enthalpy of reaction at standard conditions

Data from NIST Standard Reference Database 69: NIST Chemistry WebBook
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