10.1021/jo9022414.s001 Barbara Bankiewicz Barbara Bankiewicz Sławomir Wojtulewski Sławomir Wojtulewski Sławomir J. Grabowski Sławomir J. Grabowski Intramolecular Double Proton Transfer from 2-Hydroxy-2-iminoacetic Acid to 2-Amino-2-oxoacetic Acid American Chemical Society 2010 Different criteria basis sets Quantum Theory acid intramolecular proton transfer process DFT calculations Dunning type NBO Natural Bond Orbitals Intramolecular Double Proton Transfer intramolecular interactions QTAIM MP 2 bond 2010-03-05 00:00:00 Journal contribution https://acs.figshare.com/articles/journal_contribution/Intramolecular_Double_Proton_Transfer_from_2_Hydroxy_2_iminoacetic_Acid_to_2_Amino_2_oxoacetic_Acid/2786407 The double intramolecular proton transfer process which transforms 2-hydroxy-2-iminoacetic acid into 2-amino-2-oxoacetic acid is analyzed. The MP2 and DFT calculations were performed for different tautomers and conformers of these species. Pople style (6-311++G(d,p), 6-311++G(3df,3pd)) and Dunning type (aug-cc-pVTZ) basis sets were applied. O−H···O, N−H···O, and O−H···N intramolecular hydrogen bonds were also analyzed with the use of Quantum Theory of “Atoms in Molecules” (QTAIM) as well as Natural Bond Orbitals (NBO) method. Different criteria of the hydrogen bonding existence were applied here for intramolecular interactions. It was found that some of N−H···O hydrogen bonds may be treated as blue-shifting ones.