The Role of Prussian Blue-Thallium and Potassium Similarities and Differences in Crystal Structures of Selected Cyanido Complexes of W, Fe and Mo

The synthesis and single X-ray crystal structures of Tl(2)[W(CN)(6)(bpy)]·H(2)O, Tl[W(CN)(6)(bpy)], Tl(57)[{Fe(CN)(6)}(12){NO(3)}(9)]·9H(2)O, Tl(4)[W(CN)(8)] and Tl(4)[Mo(CN)(8)] are described. Salts crystalize in the monoclinic or trigonal (Fe) space group. For all complexes, the very unusual “side-on” coordination of Tl to C and N of cyanido ligands is observed and compared to potassium cations. The very strong bonding to cyanido ligands with an 8–13 coordination number of thallium is described and discussed. The difference between potassium and thallium bonding is an indication of the biological activity of thallium and the role of Prussian blue in the thallium detoxification procedure.