Low temperature matrix-isolation and solid state vibrational spectra of 5-chlorotetrazole

Bugalho, Susana C. S.; Serra, Arménio C.; Lapinski, L.; Cristiano, Maria Lurdes Santos; Fausto, R.

http://hdl.handle.net/10400.1/4248

Use this identifier to reference this record.

Name:	Description:	Size:	Format:
Low temperature matrix-isolation and solid state vibrational spectra.pdf		201.14 KB	Adobe PDF	Download

Send Feedback

Authors

Bugalho, Susana C. S.

Serra, Arménio C.

Lapinski, L.

Cristiano, Maria Lurdes Santos

Fausto, R.

Abstract(s)

The vibrational spectra of 5-chlorotetrazole (CN4HCl) isolated in an argon matrix (T ¼ 8.5 K) and in the solid state (at room temperature) were studied. The infrared spectrum of monomers of 5-chlorotetrazole isolated in an argon matrix agrees well with the spectrum predicted theoretically (DFT(B3LYP)/6-31G*) for the 2Htautomer of the compound. The bands assigned to the 1H-tautomer appear in the experimental spectrum as very low intensity features. Based on the relative intensities of the bands in the spectra of the 1H- and 2Htautomers, the relative amount of the first tautomer in this matrix can be estimated as 1%. Three matrixes were deposited with different nozzle temperatures and the enthalpy difference between the tautomers DH ¼ 8.0 kJ mol 1 was estimated using the Van’t Hoff relation. The internal energy difference between the two tautomers was predicted theoretically (DFT B3LYP/6-31G*) as 12.6 kJ mol 1. This is in reasonable agreement with experimental observations. In the crystalline phase, this compound exists in its 1H-tautomeric form. Accordingly, the IR spectrum of polycrystalline 5-chlorotetrazole is well reproduced by the spectrum predicted theoretically for the 1H- tautomer.

URI

http://hdl.handle.net/10400.1/4248

Citation

Bugalho, Susana C.S; Serra, A.C.; Lapinski, L.; Cristiano, M.L.S.; Fausto, R. Low temperature matrix-isolation and solid state vibrational spectra of 5-chlorotetrazole, Physical Chemistry Chemical Physics, 4, 1725-1731, 2002.