1. Tamás Vörös, Győző György Lajgút, Gábor Magyarfalvi, György Tarczay
Photochemical generation of H2NCNX, H2NNCX, H2NC(NX) (X = O, S) in low-temperature matrices
Tamás Vörös, Győző György Lajgút, Gábor Magyarfalvi, György Tarczay
Eötvös Loránd University, Laboratory of Molecular Spectroscopy
Budapest, Hungary
2017

2. Outline of the presentation
Introduction, goals of our studies
Computational results
Experimental results [NH2, C, N, O] system [NH2, C, N, S] system
Summary

3. Outline of the presentation
Introduction, goals of our studies
Computational results
Experimental results [NH2, C, N, O] system [NH2, C, N, S] system
Summary

4. Introduction Relative abundance of covalent pseudohalogen isomers
Properties of interstellar or circumstellar clouds
Sgr B2:
HNCO, HOCN
HNCS, HSCN
TCM-1:
HCNO
67P/Churyumov-Gerasimenko:
CH3CNO

5. Introduction H2N-R -CNX -NCX -XCN -XNC -C(NX) X = O X = S
500 °C pyrolysis
Ar, 10K
[1]
H2NNCO
mass-spectrometry
[2]
H2NCNS
[1] J. H. Teles, G. Maier, Chem. Ber. 122, 745, 1989.
[2] R. Flammang et al., J. Phys. Chem. 100, 17452, 1996.

6. Goals of our studies To study the [NH2, C, N, X] (X = O, S) isomers
using quantum-chemical methods to compute: - equilibrium structures, relative energies - harmonic and anharmonic wavenumbers, IR intensities and UV excitation energies
using matrix-isolation technique to: - generate and spectroscopically identify new [NH2, C, N, X] isomers from 3,4-diaminofurazan, and 3,4-diaminothiadiazole

7. Matrix isolation setup
Vacuum system
Rotational pump
Turbom. pump
Cryostat
Cryostat
Probe
Cooling system
Sample preparing system

8. Outline of the presentation
Introduction, goals of our studies
Computational results
Experimental results [NH2, C, N, O] system [NH2, C, N, S] system
Summary

9. [NH2, C, N, X] (X = O, S) isomers
fc CCSD(T)/cc-pVTZ equilibrium structures and ZPVE corrected relative energies

10. IR wavenumbers and intensities of [NH2, C, N, O] isomers
fc CCSD(T)/cc-pVTZ harmonic wavenumbers corrected by B3LYP/cc-pVTZ anharmonic contributions (in cm-1)
fc CCSD(T)/cc-pVTZ harmonic intensities (in km mol-1)
H2NNCO
H2NCNO
H2NOCN
H2NONC
H2NC(NO)
3348 (6.0)
3417 (35)
3353 (5.5)
3360 (4.8)
3564 (58)
3316 (2.0)
3365 (20)
3275 (0.9)
3286 (0.6)
3458 (54)
2235 (853)
2328 (228)
2243 (85)
2063 (43)
1794 (270)
1618 (15)
1610 (25)
1561 (32)
1595 (30)
1579 (25)
1385 (15)
1378 (252)
1292 (5.8)
1311 (4.9)
1394 (34)
1304 (2.9)
1183 (52)
1208 (83)
1199 (77)
1034 (8.3)
1067 (70)
858 (13)
1072 (51)
862 (14)
962 (10)
847 (8.3)
609 (202)
807 (4.7)
817 (13)
614 (56)
650 (35)
471 (17)
607 (2.1)
529 (23)
468 (189)
588 (22)
497 (1.9)
446 (20)
441 (29)

11. IR wavenumbers and intensities of [NH2, C, N, S] isomers
fc CCSD(T)/cc-pVTZ harmonic wavenumbers corrected by B3LYP/cc-pVTZ anharmonic contributions (in cm-1)
fc CCSD(T)/cc-pVTZ harmonic intensities (in km mol-1)
H2NNCS
H2NCNS
H2NSCN
H2NSNC
H2NC(NS)
H2NN(CS)
3399 (15)
3460 (55)
3456 (29)
3456 (33)
3559 (51)
3379 (18)
3313 (1.8)
3384 (51)
3370 (19)
3365 (12)
3445 (50)
3296 (7.1)
2000 (622)
2250 (50)
2170 (<1)
2033 (176)
1792 (159)
1690 (14)
1598 (21)
1598 (20)
1580 (9.4)
1590 (17)
1587 (34)
1617 (24)
1320 (36)
1153 (<1)
1099 (<1)
1098 (<1)
1218 (70)
1310 (8.1)
1139 (59)
1121 (187)
842 (52)
875 (24)
1048 (14)
1043 (46)
897 (131)
322 (286)
657 (15)
608 (27)
677 (19)
843 (88)
701 (24)
573 (11)
553 (75)
563 (204)
548 (85)
615 (13)
524 (61)
455 (0.34)
504 (34)
478 (18)
416 (2.2)
415 (1.5)
410 (14)
444 (174)

12. [NH2, C, N, X] (X = O, S) – NH2CN complexes
B3LYP/cc-pVTZ equilibrium structures
H2NCNO : H2NCN
H2NNCO : H2NCN
H2NC(NO) : H2NCN
H2NCNS : H2NCN
H2NNCS : H2NCN
H2NC(NS) : H2NCN

13. Outline of the presentation
Introduction, goals of our studies
Computational results
Experimental results [NH2, C, N, O] system [NH2, C, N, S] system
Summary

14. MI-IR spectra of 3,4-diaminofurazan
in argon
in krypton
B3LYP/aug-cc-pVTZ harmonic wavenumbers and IR intensities

15. MI-UV spectrum of 3,4-diaminofurazan in argon
deposited
20 min photolysis at 254 nm
+ 15 min photolysis at BBUV

16. Photolysis of 3,4-diaminofurazan in argon
a) 3 hours 213 nm photolysis – deposited
b) 3 hours 239 nm photolysis – deposited
c) and d) H2NCNO:H2NCN and H2NNCO:H2NCN (B3LYP/cc-pVTZ anharmonic wavenumbers and intensities)
e) H2NC(NO) (fc CCSD(T)/cc-pVTZ harmonic wavenumbers + B3LYP/cc-pVTZ anharmonic contributions (IR intensities: harmonic fc CCSD(T)/cc-pVTZ))

17. Photolysis of 3,4-diaminofurazan in krypton
a) 3 hours 213 nm photolysis – deposited
b) 3 hours 239 nm photolysis – deposited
c) and d) H2NCNO:H2NCN and H2NNCO:H2NCN (B3LYP/cc-pVTZ anharmonic wavenumbers and intensities)
e) H2NC(NO) (fc CCSD(T)/cc-pVTZ harmonic wavenumbers + B3LYP/cc-pVTZ anharmonic contributions (IR intensities: harmonic fc CCSD(T)/cc-pVTZ))

18. Photolysis of 3,4-diaminofurazan in argon
H2NCNO:H2NCN
H2NNCO:H2NCN
H2NC(NO)

19. Outline of the presentation
Introduction, goals of our studies
Computational results
Experimental results [NH2, C, N, O] system [NH2, C, N, S] system
Summary

20. MI-IR spectra of 3,4-diaminothiadiazole
in argon
in krypton
B3LYP/aug-cc-pVTZ harmonic wavenumbers and IR intensities

21. MI-UV spectrum of 3,4-diaminothiadiazole in argon
deposited
15 min photolysis at 254 nm
+ 15 min photolysis at BBUV

22. Photolysis of 3,4-diaminothiadiazole in argon
a) 3 hours 221 nm photolysis – deposited
b) 3 hours 280 nm photolysis – deposited
c) H2NC(NS) (fc CCSD(T)/cc-pVTZ harmonic wavenumbers + B3LYP/cc-pVTZ anharmonic contributions (IR intensities: harmonic fc CCSD(T)/cc-pVTZ))
d) and e) H2NNCS:H2NCN and H2NCNS:H2NCN (B3LYP/cc-pVTZ anharmonic wavenumbers and intensities)

23. Photolysis of 3,4-diaminothiadiazole in krypton
a) 3 hours 221 nm photolysis – deposited
b) 3 hours 280 nm photolysis – deposited
c) H2NC(NS) (fc CCSD(T)/cc-pVTZ harmonic wavenumbers + B3LYP/cc-pVTZ anharmonic contributions (IR intensities: harmonic fc CCSD(T)/cc-pVTZ))
d) and e ) H2NNCS:H2NCN and H2NCNS:H2NCN (B3LYP/cc-pVTZ anharmonic wavenumbers and intensities)

24. MI-IR spectra of 3,5-diamino-1,2,4-thiadiazole
in argon
in krypton
B3LYP/aug-cc-pVTZ harmonic wavenumbers and IR intensities

25. MI-UV spectrum of 3,5-diamino-1,2,4-thiadiazole in argon
deposited
30 min photolysis at 254 nm
+ 15 min photolysis at BBUV

26. Photolysis of 3,5-diamino-1,2,4-thiadiazole
a) 3 hours 240 nm photolysis – deposited in argon
b) 3 hours 250 nm photolysis – deposited in krypton
c) HNNCHS:H2NCN (MP2/cc-pVTZ harmonic wavenumbers + B3LYP/cc-pVTZ anharmonic contributions (IR intensities: harmonic MP2/cc-pVTZ))

27. Photolysis of 3,5-diamino-1,2,4-thiadiazole in argon
H2NCNS:H2NCN c) H2NC(NS)
H2NNCS:H2NCN d) HNNCHS:H2NCN

28. Outline of the presentation
Introduction, goals of our studies
Computational results
Experimental results [NH2, C, N, O] system [NH2, C, N, S] system
Summary

29. Summary [1] H2NCNO H2NNCO H2NC(NO) H2NCNS H2NNCS H2NC(NS) HNNHCS H2N-R
-CNX
-NCX
-XCN
-XNC
-C(NX)
X = O !
X = S
[1] T. Voros, G. G. Lajgut, G. Magyarfalvi, G. Tarczay, J. Chem. Phys. 146, , 2017.