Bonding nature of coordination polymers, M(II)3[Rh(CN)6]2·xH2O

Abstract A series of coordination polymers of the type M (II) 3 [Rh(CN) 6 ] 2 · x H 2 O ( M ( II ) = Mn, Fe, Co, Ni, Cu or Zn and x = 7–15) have a f.c.c.unit cell typical of Prussian blue analogs. Magnetic data and the dependence of the lattice constants on the crystal field stabilization energy of M ( II ) indicate that M ( II ) coordinated by four nitrogen ends of cyanide ligands and two water molecules is in the high spin state and that carbon-coordinated Rh(III) is in the low spin state. In the i.r. spectra both CN and RhC stretching vibrations show the shift to the higher frequency side compared with those of the parent complex K 3 [Rh(CN) 6 ]. This shift was explained by the linkage structure RhCNM(II) of cyanide ligands. The absorption bands observed in the visible region were assigned to the d - d transitions of M ( II ) in the octahedral weak field, while those observed in the near u.v. region were assigned to the ligand field bands of Rh(III) in the octahedral strong field.