The substitution reactions of the bridged dinuclear Rh(II) complex Rh2(uO2CCH3)4XY have been studied by M.A.S Aquino and D.H. Macartney. Reaction rates illustrate little dependence on the choice of the entering group. The table shows the dependence on the leaving group X as well as the ligand on the opposite Rh, trans Y, at 298K. Explain what conclusion can you draw concerning the mechanism?