[Co(NH)] is diamagnetic, with a low-spin 3d octahedral Co(III) center. The cation obeys the 18-electron rule and is considered to be a classic example of an exchange inert metal complex.  As a manifestation of its inertness, [Co(NH)]Cl can be recrystallized unchanged from concentrated hydrochloric acid: the NH is so tightly bound to the Co(III) centers that it does not dissociate to allow its protonation. In contrast, labile metal ammine complexes, such as [Ni(NH)]Cl, react rapidly with acids, reflecting the lability of the Ni(II)–NH bonds.  Upon heating, hexamminecobalt(III) begins to lose some of its ammine ligands, eventually producing a stronger oxidant.
)] is a moderately strong Bronsted acid.
The chloride ions in [Co(NH)]Cl can be exchanged with a variety of other anions such as nitrate, bromide, iodide, sulfamate to afford the corresponding [Co(NH)]X derivative.  Such salts are orange or bright yellow and display varying degrees of water solubility. The chloride ion can be also exchanged with more complex anions such as the hexathiocyanatochromate(III), yielding a pink compound with formula [Co(NH)] [Cr(SCN)], or the ferricyanide ion.