However under the standard conditions the title compounds are pure keto- tautomers
which is consistent with the experimental results.
1]H NMR) and UV-vis spectroscopy, X-ray analysis (20), (21) or fluorescence spectroscopy (22), (23), the latter arguing the formation of keto tautomer
accompanied of a large Stokes shift (100 nm).
Deprotonation of these two tautomers
in aqueous solution is also investigated.
Once the structure is drawn, the program can check for tautomers
, and adjust the bond length and angle according to hybridization simplifying the task of drawing complex structures.
alkylsilylation of aldohexoses yields four cyclic tautomers
in various amounts.
For the first time the values of proton affinities were calculated taking into account the contributions of rare tautomers
of cytosine and guanine and the ir protonated forms.
3] showed the following characteristics: a complex series of signals at 1-4 ppm which we assigned to various aliphatic protons, the number of peaks being doubled because both enol and keto tautomers
were present (Fig.