For the other transition metals, the transition metals retain octahedral coordination, even though tetrahedral Co(II) is wellknown, and so they adopt structures more closely related to the M[Bi(SCN) 6 ] structure. Compounds 1-4 all contain Bi(NCS) vacancies, and a key difference in these structures is how the resultant voids are filled and the open structures are stabilised. This is also a feature of the cyanide Prussian blues, which contain significant quantities of zeolitic water. These thiocyanate frameworks have more complex structures than reported for PBAs, although similar complexity may be present in cyanide compounds but be more difficult to detect due to their higher symmetries.