Through an appropriate change of reference frame and rescalings of the variables and the parameters introduced, the Hamiltonian of the three--body problem is written as a perturbed Kepler problem. In this system, new Delaunay variables are defined and a suitable configuration of the phase space and the mass parameters is chosen. In such a system, wide regions of librational and rotational motions where orbits are regular and stable are found. Close to the separatrix of these regions, the existence of chaotic motions presenting a double rotational and librational dynamics is proved, numerically, through Poincaré sections and the use of FLI.
MSC Classification: 37N05 , 37J12 , 37J40 , 37J46 , 37D10