We performed a time-dependent wave packet study to investigate the fragmentation and recombination of the I-2-Ar Van der Waals complex following excitation above the B-state dissociation limit. Based on a recently published nb initio potential energy surface of the ground state [C. F. Kunz, I. Burghardt, and B. Hess, J. Chem. Phys. 109, 359 (1998)], we studied the possible kinematic origin of the "one-atom cage effect" by three-dimensional wave packet propagation within the rotational infinite order sudden approximation. We found that final vibrational distributions depend strongly on the ground and excited state equilibrium geometries. Taking uncertainties in the excited state potential into account, we confirm a possible kinematic origin of the one-atom cage effect from a collinear isomer of the I2-Ar complex, initially proposed by Valentini and Cross [J. J. Valentini and J. B. Cross, J. Chem. Phys. 77, 572 (1982)].