Static and Dynamic Properties of Fluorinated 4-Aryl-1,5-Benzodiazepinones
Six 4-aryl-6,7,8,9-tetrafluoro-1,5-benzodiazepine-2-ones have been synthesized and fully characterized by 1H, 13C, 15N and 19F NMR in solution and in the solid state. In addition, the structures of three of them have been determined by X-ray crystallography. The imine/enamine tautomerism has been experimentally studied by NMR in solution (in the solid state, only the imino tautomer is present). Three barriers corresponding to the inversion of the seven-membered ring have been determined (N1-unsubstituted derivatives). Both for the tautomerism and for the conformational aspects, theoretical calculations at the B3LYP/6-311++G(d,p) level including GIAO calculations of the NMR chemical shifts have been carried out with satisfying results. Different energy profiles have been considered and several transition states located.