Reactive scattering of Cl atoms with C3H7I molecules has been studied over the range of initial translational energyE= 46-25 kJ mol-1, using a supersonic beam of Cl atoms seeded in He and Ne buffer gas. Laboratory angular and velocity distributions of ICl product were measured which show reaction proceeding via a long-lived collision complex at low initial translational energy. However a forward scattered component with a higher product translational energy appears at intermediate and higher initial translational energy. The decreased lifetimes for complexes formed in large impact parameter collisions and the high product translational energies reflect the reduced density of vibrational states prevailing for complexes with large values of the total angular momentumJ≲ 300 ħ.