화학공학소재연구정보센터
Inorganic Chemistry, Vol.45, No.2, 582-590, 2006
Syntheses, structures, and magnetic properties of cyano-bridged heterobimetallic complexes based on [Fe(bpca)(CN)(3)](-)
Two new cyano-bridged one-dimensional heterobimetallic coordination polymers, [(bpca)(2)Fe-2(III)(CN)(6)Cu(H2O)(2)center dot 1.5H(2)O](n) (2) and [(bpca)Fe-III(CN)(3)Cu(bpca)(H2O)center dot H2O](n) (3), and a trinuclear complex, [(bpca)(2)Fe-2(III)(CN)(6)Mn(CH3OH)(2)(H2O)(2)]center dot 2H(2)O (4), have been synthesized using the tailored tricyanometalate precursor (Bu4N)[Fe(bpca)(CN)(3)]center dot H2O (1) (Bu4N+ = tetrabutylammonium cation; bpca = bis(2-pyridylcarbonyl)amidate anion) as a building block and structurally characterized. In complex 2, the Cu-II ions are six-coordinated in an elongated distorted octahedral environment, and they are linked by distorted octahedrons of [Fe(bpca)(CN)(3)](-) to form 1D chain of squares. Complex 3 is an unexpected chiral heterobimetallic helical chain complex, in which the helical chain consists of the asymmetric unit of [(bpca)Fe(CN)(3)Cu(bpca)(H2O)]. In complex 4, there are two independent trinuclear clusters in one asymmetric unit, and the coordination modes of the two methanol and two water molecules coordinating to the central Mn(II) ion are different (cis and trans). Complex 2 shows metamagnetic behavior with a Neel temperature of T-N = 2.2 K and a critical field of 250 Oe at 1.8 K, where the cyanides mediate the intrachain ferromagnetic coupling between the Cu-II and Fe-III ions. Complex 3 shows ferromagnetic coupling between Cu-II and Fe-III ions, the best-fit for chi(M)T versus T using a 1 D alternating chain model leads to the parameters J(1) = 7.9(3) cm(-1), J(2) = 1.03(2) cm(-1), and g = 2.196(3). Complex 4 exhibits ferrimagnetic behavior caused by the noncompensation of the local interacting spins (S-Mn = 5/2 and S-Fe = 1/2) which interact antiferromagnetically through bridging cyano groups.