Structural Characterization of Cadmium Hexacyanometallates(II) and Related Complexes

Cadmium hexacyanometallates (II) crystallize in the same monoclinic cell (space group C 5 2h −P2 1/n ) reported for the analogs of manganous complexes. In that monoclinic framework, two outer cations (M = Mn 2+ or Cd 2+ ) of neighboring structural units M 2 [L II (CN) 6 ], (L = Fe II , Ru II , Os II ), are linked by two common water molecules. On heating above 100°C, these water bridges are removed. In dehydrated complexes, the outer cation (M) remains linked to only three CN ligands. The loss of aquo-ligands induces a remarkable π-back donation from the inner cation (L) to CN ligands, which was studied using IR, Raman, and Mössbauer spectroscopies.