The rate for the hydrolysis of cobalt(III) ammine halide complexes are deceptive, appearing to be associative but proceeding by an alternative pathway. The hydrolysis of [Co(NH)Cl] follows second order kinetics: the rate increases linearly with concentration of hydroxide as well as the starting complex. Based on this information, the reactions would appear to proceed via nucleophilic attack of hydroxide at cobalt. Studies show, however, that the hydroxide deprotonates one NH ligand to give the conjugate base of the starting complex, i.e., [Co(NH)(NH)Cl].  In this monovalent cation, the chloride spontaneously dissociates. This pathway is called the S1cB mechanism.