# Is associative ligand exchange possible with octahedral complexes?

Can associative ligand exchange produce an octahedral intermediate as long as the initial complex has 16 electrons (unsaturated)?

Not sure. all I ever see is a square planar turning into a trigonal bipyramidal intermediate?

Also, it should be mentioned that the number of electrons in each structure does not have to be 18 or less. Many (pseudo)octahedral complexes such as $\ce{[Co(H2O)6]^2+}$, $\ce{[Cu(NH3)4(H2O)2]^2+}$ or $\ce{[Ni(H2O)6]^2+}$ have more than 18 electrons and are fully comfortable with it.