Profiles of and complexes in two-cation Liesegang systems

Liesegang patterns of Co(OH)2 and Ni(OH)2 seemingly migrate in space as time advances because of redissolution of the bands in excess NH4OH. The formation of the complexes Co ( NH 3 ) 6 2 + and Ni ( NH 3 ) 6 2 + drives the redissolution, and significantly couples to the diffusion and precipitation reaction processes. We determine here the spatial profiles of the latter complexes along with their time evolution, for two sets of experiments performed under different conditions. The more favored formation of Ni ( NH 3 ) 6 2 + over Co ( NH 3 ) 6 2 + seems to control the entire dynamics of this complex system.