Vibrational spectra and structures of the anions of urazole and 4-methylurazole: DFT calculations of the normal modes and the influence of hydrogen bonding.
Solid state IR and Raman as well as aqueous solution state Raman spectra are reported for the anions of urazole and 4-methylurazole, and their N-deuterated derivatives. DFT calculations, at the B3-LYP/cc-pVTZ level, established that the structures and vibrational spectra of both anions can be interpreted using a model that incorporates hydrogen-bonded water molecules, in conjunction with the polarizable continuum solvation method. In the case of the urazole anion it is shown that deprotonation occurs primarily at N1 rather than N4, but there is also evidence for the second tautomer both in the solid state and in aqueous solution. The vibrational spectra were computed at the optimised molecular geometry in each case, enabling normal coordinate analysis, which yielded satisfactory agreement with the experimental IR and Raman data. Computed potential energy distributions of the normal modes provided detailed vibrational assignments.
School of Science, University of Greenwich at Medway, Central Avenue, Chatham Maritime, Kent, UK.
John P
JP
Ryall
Trevor J
TJ
Dines
Babur Z
BZ
Chowdhry
Stephen A
SA
Leharne
Robert
R
Withnall
D000838:Anions / Q000737:chemistry*; D003198:Computer Simulation; D006860:Hydrogen Bonding; D015394:Molecular Structure; D011789:Quantum Theory; D013055:Spectrophotometry, Infrared / Q000379:methods*; D013059:Spectrum Analysis, Raman / Q000379:methods*; D014230:Triazoles / Q000737:chemistry*; D014732:Vibration
D000838:Anions; D014230:Triazoles; C421465:urazole