We propose a very simple and efficient way to stabilize ions issued from a collision complex through a femtosecond coherently controlled pump/probe process. Starting from a van der Waals complex, one can initiate a collision at a well-defined time and with a restricted impact parameter. Formation of stable ionic complex can be achieved by ionizing the collision complex at the "right time." We present in this paper its application to the NaI-(CH3CN)(1-2) system. Na+-CH3CN ion formation is coherently controlled by ionization of colliding Na atom on CH3CN molecules issued from the dissociation of NaI within NaI-(CH3CN)(1-2). Classical mechanic calculations using simple ionization/dissociation conditions can reproduce the experimental data and give an insight into the control of such a reaction.