Diimide

Formula: H₂N₂
Molecular weight: 30.0293
CAS Registry Number: 3618-05-1
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Data at other public NIST sites:
- Gas Phase Kinetics Database
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Gas phase ion energetics data

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 H₂N₂⁺ (ion structure unspecified)

Quantity	Value	Units	Method	Reference	Comment
Proton affinity (review)	803.	kJ/mol	N/A	Hunter and Lias, 1998	HL
Quantity	Value	Units	Method	Reference	Comment
Gas basicity	772.3	kJ/mol	N/A	Hunter and Lias, 1998	HL

Ionization energy determinations

IE (eV)	Method	Reference	Comment
9.589 ± 0.007	PI	Ruscic and Berkowitz, 1991	T = 0K; LL
9.80 ± 0.05	EI	Wiberg, Fischer, et al., 1979	LLK
9.7 ± 0.1	EI	Willis, Lossing, et al., 1976	LLK
9.59 ± 0.01	PE	Frost, Lee, et al., 1976	LLK
9.59	PE	Frost, Lee, et al., 1975	LLK
9.9	EI	Melton, 1966	RDSH
9.9 ± 0.1	EI	Foner and Hudson, 1958	RDSH

Appearance energy determinations

Ion	AE (eV)	Other Products	Method	Reference	Comment
HN₂⁺	10.905 ± 0.019	H	PI	Ruscic and Berkowitz, 1991	T = 356K; LL
HN₂⁺	10.954 ± 0.019	H	PI	Ruscic and Berkowitz, 1991	T = 0K; LL
HN₂⁺	11.33 ± 0.05	H	EI	Wiberg, Fischer, et al., 1979	LLK
HN₂⁺	10.98 ± 0.05	H	EI	Willis, Lossing, et al., 1976	LLK
H₂⁺	13.403 ± 0.036	N₂	PI	Ruscic and Berkowitz, 1991	T = 0K; LL
H₂⁺	13.353 ± 0.036	N₂	PI	Ruscic and Berkowitz, 1991	T = 356K; LL
N₂⁺	14.00 ± 0.05	H₂	EI	Willis, Lossing, et al., 1976	LLK

References

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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]

Ruscic and Berkowitz, 1991
Ruscic, B.; Berkowitz, J., Photoionization mass spectrometric study of N₂H₂ and N₂H₃: N-H, N=N bond energies and proton affinity of N₂, J. Chem. Phys., 1991, 95, 4378. [all data]

Wiberg, Fischer, et al., 1979
Wiberg, N.; Fischer, G.; Bachhuber, H., Diazen und andere Distickstoffhydride: Bildungswarmen, Dissoziationsenergien, Auftrittspotentiale, Protonenaffinitaten, Z. Naturforsch. B:, 1979, 34, 1385. [all data]

Willis, Lossing, et al., 1976
Willis, C.; Lossing, F.P.; Back, R.A., The heat of formation of N₂H₂ and the proton affinity of N₂, Can. J. Chem., 1976, 54, 1. [all data]

Frost, Lee, et al., 1976
Frost, D.C.; Lee, S.T.; McDowell, C.A.; Westwood, N.P.C., The photoelectron spectra of diazene, diazene-d2, trans-methyldiazene, J. Chem. Phys., 1976, 64, 4719. [all data]

Frost, Lee, et al., 1975
Frost, D.C.; Lee, S.T.; McDowell, C.A.; Westwood, N.P.C., The photoelectron spectrum of diazene (diimine), Chem. Phys. Lett., 1975, 30, 26. [all data]

Melton, 1966
Melton, C.E., Study by mass spectrometry of the decomposition of ammonia by ionizing radiation in a wide-range radiolysis source, J. Chem. Phys., 1966, 45, 4414. [all data]

Foner and Hudson, 1958
Foner, S.N.; Hudson, R.L., Diimide-identification and study by mass spectrometry, J. Chem. Phys., 1958, 28, 719. [all data]

Notes

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Symbols used in this document:

AE Appearance energy
Data from NIST Standard Reference Database 69: NIST Chemistry WebBook
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