Prototropic tautomerism of 3,5-(oxo/thioxo) derivatives of 2,7-dimethyl-1,2,4-triazepinesElectronic supplementary information (ESI) available: the B3LYP/6-31G* optimized geometries of all the structures included in Fig. 1 and the corresponding TS. See http://www.rsc.org/suppdata/nj/b1/b109397e/ | Publicación