Photochemistry and vibrational spectra of matrix-isolated 5-ethoxy-1-phenyl-1H-tetrazole. | - CCMAR -

Journal Article

TítuloPhotochemistry and vibrational spectra of matrix-isolated 5-ethoxy-1-phenyl-1H-tetrazole.
Publication TypeJournal Article
AuthorsFrija, LMT, Reva, ID, Gómez-Zavaglia, A, Cristiano, MLS, Fausto, R
Year of Publication2007
JournalJ Phys Chem A
Volume111
Questão15
Date Published2007 Apr 19
Pagination2879-88
ISSN1089-5639
Palavras-chaveAzides, Chemistry, Physical, Cyanates, Light, Molecular Conformation, Molecular Structure, Photochemistry, Protein Conformation, Spectrophotometry, Infrared, Temperature, Tetrazoles, Thermodynamics
Abstract

A combined matrix isolation FT-IR and theoretical DFT(B3LYP)/6-311++G(d,p) study of the molecular structure and photochemistry of 5-ethoxy-1-phenyl-1H-tetrazole (5EPT) was performed. A new method of synthesis of the compound is described. Calculations show three minima, very close in energy and separated by low-energy barriers (less than 4 kJ mol-1), in the ground-state potential energy profile of the molecule. The method of matrix isolation enabled the reduction of the number of populated conformational states in the experiment at low temperature due to the effect known as conformational cooling. As a result, the spectrum of the as-deposited matrix of 5EPT closely matches that of the most stable conformer predicted theoretically, pointing to the existence of only this conformer in the low-temperature matrixes. In this structure, the dihedral angle between the two rings, phenyl and tetrazole, is ca. 30 degrees, whereas the ethyl group stays nearly in the plane of the tetrazole ring and is as far as possible from the phenyl group. In situ UV irradiation (lambda > 235 nm) of the matrix-isolated 5EPT induced unimolecular decomposition, which led mainly to production of ethylcyanate and phenylazide, this later compound further reacting to yield, as final product, 1-aza-1,2,4,6-cycloheptatetraene. Anti-aromatic 3-ethoxy-1-phenyl-1H-diazirene was also observed experimentally as minor photoproduct, resulting from direct extrusion of molecular nitrogen from 5EPT. This species has not been described before and is now characterized by infrared spectroscopy for the first time.

DOI10.1021/jp068556h
Sapientia

http://www.ncbi.nlm.nih.gov/pubmed/17388403?dopt=Abstract

Alternate JournalJ Phys Chem A
PubMed ID17388403