Magnetism of cyano-bridged hetero-one-dimensional Ln3+-M3+ complexes (Ln3+ = Sm, Gd, Yb; M3+ = FeLS, Co)

The reaction of Ln(NO3)(3).aq with K-3[Fe(CN)(6)] Or K-3[Co(CN)(6)] and 2,2'-bipyridine in water led to five one-dimensional complexes: trans-[M(CN)(4)(mu-CN)(2)Ln(H2O)(4) (bpy)](n).XnH(2)O.1.5nbpy (M = Fe3+ or CO3+; Ln = Sm3+, Gd3+, or Yb3+; X = 4 or 5). The structures for [Fe3+-Sm3+] (1), [Fe3+-Gd3+] (2), [Fe3+-Yb3+] (3), [CO3+-Gd3+] (4), and [CO3+-Yb3+] (5) have been solved; they crystallize in the triclinic space P (1) over bar and are isomorphous. The [Fe3+-SM3+] complex is a ferrimagnet, its magnetic studies suggesting the onset of weak ferromagnetic 3-D ordering at 3.5 K. The [Fe3+-Gd3+] interaction is weakly antiferromagnetic. The isotropic nature of Gd3(+) allowed us to evaluate the exchange interaction (J = 0.77 cm(-1)).