One-Dimensional Homochiral Cyano-Bridged Heterometallic Chain Coordination Polymers with Metamagnetic or Ferroelectric Properties

Two couples of enantiomerically pure chiral cyano-bridged heterobimetallic chain coordination polymers, [Mn((R,R)-Salcy)Fe(Tp)(CN)₃·H₂O·1/2CH₃CN]_n (1), [Mn((S,S)-Salcy)Fe(Tp)(CN)₃·H₂O·1/2CH₃CN]_n (2), [Mn((R,R)-Salcy)Fe(bpca)(CN)₃·H₂O]_n (3), and [Mn((S,S)-Salcy)Fe(bpca)(CN)₃·H₂O]_n (4) [(R,R)-Salcy or (S,S)-Salcy = (R,R)- or (S,S)-N,N′-(1,2-cyclohexanediylethylene)bis(salicylideneiminato) dianion, Tp = tris(pyrazolyl)hydroborate, bpca = bis(2-pyridylcarbonyl)amidate anion], were synthesized using the modified cyanometalate building blocks [Fe(L)(CN)₃]⁻ (L = Tp, bpca) and the chiral polydentate Schiff base manganese(III) complex fragments. The circular dichroism measurements showed Cotton effects of the opposite sign at the same wavelength for each pair of enantiomers. Magnetic property studies indicated that complexes 1 and 2 show not only intrachain but also interchain field-induced metamagnetic transitions from an antiferromagnetic to a ferromagnetic state and exhibit an antiferromagnetic long-range ordering with a T_N of 3.2 K, while enantiomers 3 and 4 are typical antiferromagnetic coupling compounds. Furthermore, complex 3 exhibits a ferroelectric behavior that relates to the polar point group C₂, in which it crystallizes.