The complexes $[\text{Co}({\text{NH}}_3{)}_6][\text{Cr}(\text{CN}{)}_6]$ and $[\text{Cr}({\text{NH}}_3{)}_6][\text{Co}(\text{CN}{)}_6]$ are the examples of which type of isomerism?

Coordination isomerism occurs in compounds containing both complex cation and complex anion, where ligands are exchanged between the two metal centers. Here, ${\text{NH}}_3$ and ${\text{CN}}^{-}$ are swapped between Co and Cr.