What Could Formations of Linkage Isomers of [Co(NH₃)₅NO₂]²⁺ be like?
This Co-ordination compound of were studied by Jorgensen and Werner who observed that were two compounds of the same chemical formula but of different colors. (We can see these two geometries in the image). 
A red form of low stability converted readily to a yellow form the $\ce{M-NO2}$ nitro isomer, based on comparison with compounds with similar colors. This conclusion was later confirmed, and kinetic and $\ce{^{18}O}$ labeling experiments showed that conversion of one form to the other is strictly intramolecular, not a result of dissociation of the $\ce{NO2^-}$ ion followed by reattachment. 

References:
Miessler, Tarr,Inorg. Chem., 2nd Edition, 1998