An ab initio study of stability of lowest singlet and triplet states of aminofurazans

PHYS 601

Alexander V. Gaenko, galexvg@gmail.com, Chemistry Department, State University of New York, University at Buffalo, 345 Natural Science Complex, Buffalo, NY 14260-3000 and Ajitha Devarajan, ajitha.devarajan@gmail.com, Chemistry Department, State University of New York at Buffalo, Natural Sciences Complex, Buffalo, NY 14260-3000.
Lowest singlet and triplet excited states of substituted aminofurazans (3-amino-4-R-1,3,5-oxadiazoles) with R=H, CH3, NH2, OCH3, OCOH, N3, NO2, their imino tautomers and protonated forms were optimized using ab initio methods. TDDFT with B3LYP functional, RI-CC2 and for specific case MS-CASPT2 methods with cc-pVDZ basis set were used. Azido derivative structure is predicted to be unstable due to N2 elimination in both S1 and T1 states. In case of S1 state of nitro derivative, a proton transfer from NH2 to NO2 is predicted, apparently a Nitro Assisted Proton Transfer (NAPT). In case of derivatives with R=H, CH3, NH2, OCH3, OCOH, instability due to ring opening at the O(1)-N(5) is predicted for the S1 state. The open-ring intermediate is likely to have a biradical or mesomeric nitrene like structure. The imino forms are predicted to be stable in S1 state. The photostability of the protonated forms depends on the nature of the substituent R and the site of protonation.
 

PHYS Poster Session - Computational Spectroscopy and Reaction Dynamics
7:30 PM-10:00 PM, Wednesday, April 9, 2008 Morial Convention Center -- Hall A, Poster

Division of Physical Chemistry

The 235th ACS National Meeting, New Orleans, LA, April 6-10, 2008