The one-pot double condensation reaction of 2-thenoyltrifluoroacetone (2-1TA) with ethylendiamine or o-phenylenediamine, in a 2:1 stoichiometric molar ratio, leads to the formation of 7-(thiophene-2-yl)-5-(trifluoromethyl)-2,3-dihydro-1H-1,4-diazepine 2 and 2-thiophene-4-trifluoromethy1-1,5benzodiazepine 3, that were isolated in 56 and 53% yields, respectively. The bis(trifluoroacetamide) ethylene derivative 1 was also isolated in 32% yield as a side-product in the reaction of 2-TTA and ethylenediamine. Compounds 1-3 were fully characterized by elemental analysis, FT-IR and multinuclear (H-1, C-13 and F-19) NMR spectroscopy. In addition, their molecular identities and geometries have been authenticated by single-crystal X-ray diffraction analysis. The spectroscopic and structural data confirm that the 1,4-diazepine 2 and the 1,5-benzodiazepine 3 exist in the imine-enamine and diimine tautomeric forms, respectively, both in solution and in the solid-state. (C) 2016 Elsevier B.V. All rights reserved.