Slow magnetic relaxation, antiferromagnetic ordering and metamagnetism in MnII(H2dapsc)-FeIII(CN)6 chain complex with highly anisotropic Fe-CN-Mn spin coupling
Abstract
Reactions of [Mn(H2dapsc)Cl2]∙H2O with K3[Fe(CN)6] and (PPh4)3[Fe(CN)6] lead to the formation of the chain polymeric complex {[Mn(H2dapsc)][Fe(CN)6][K(H2O)3.5]}n•1.5nH2O (1) and the discrete pentanuclear complex {[Mn(H2dapsc)]3[Fe(CN)6]2(H2O)2}• 4CH3OH•3.4H2O (2), respectively. In the crystal structure of 1 the high-spin [MnII(H2dapsc)]2+ (dapsc = 2,6-diacetylpyridinebis(semicarbazone)) cations and low-spin hexacyanoferrate(III) anions are assembled into alternating heterometallic cyano-bridged chains. The K+ ions are located between the chains and are coordinated by oxygen atoms of the H2dapsc ligand and water molecules. The magnetic structure of 1 is built from ferrimagnetic chains, which are antiferromagnetically coupled. The complex exhibits metamagnetism and frequency-dependent ac magnetic susceptibility, indicating single-chain magnetic behavior with a Mydosh-parameter phi = 0.12 and an effective energy barrier (Ueff/kB) of 36.0 K with (tau)0 = 2.34∙10-11 s for the spin relaxation. Detailed theoretical analysis showed highly anisotropic intra-chain spin coupling between [FeIII(CN)6]3- and [MnII(H2dapsc)]2+ units resulting from orbital degeneracy and unquenched orbital momentum of [FeIII(CN)6]3- complexes. Origin of metama...Continue Reading
References
Cyano-bridged Mn(III)-M(III) single-chain magnets with M(III)=Co(III), Fe(III), Mn(III), and Cr(III)
Giant Ising-type magnetic anisotropy in trigonal bipyramidal Ni(II) complexes: experiment and theory
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