Electronic energy variation with water displacement, starting from the monodentate structure (Minimum 1). All stationary points included. Values obtained with B3LYP/SDD//B3LYP/SDD. Minimum 1 taken as reference. (M1) Minimum 1 (monodentate), (M2) Minimum 2 (bidentate), (M3) Minimum 3 (bidentate), (TS1) Transition State 1, (TS2) Transition State 2.