Magnetism of Cyano-Bridged Hetero-One-Dimensional Ln^3+-M^3+ Complexes (Ln^3+ = Sm, Gd, Yb; M^3+ = FeLS, Co)

The reaction of Ln(NO3)3·aq with K3[Fe(CN)6] or K3[Co(CN)6] and 2,2ʹ-bipyridine in water led to five one-dimensional complexes: trans -[M(CN)4(-CN)2Ln(H2O)4 (bpy)]n·XnH2O·1.5nbpy (M = Fe^3+ or Co^3+; Ln = Sm3+, Gd3+, or Yb3+; X = 4 or 5). The structures for [Fe^3+-Sm^3+] (1), [Fe3+-Gd3+] (2), [Fe^3+-Yb^3+] (3), [Co^3+-Gd^3+] (4), and [Co^3+-Yb^3+] (5) have been solved; they crystallize in the triclinic space P and are isomorphous. The [Fe^3+-Sm^3+] complex is a ferrimagnet, its magnetic studies suggesting the onset of weak ferromagnetic 3-D ordering at 3.5 K. The [Fe^3+-Gd^3+] interaction is weakly antiferromagnetic. The isotropic nature of Gd3+ allowed us to evaluate the exchange interaction (J = 0.77 cm^-1).