Abstract
Two novel 1D heterobimetallic compounds {[Mn-III(SB2+)M-III(CN)(6)]center dot 4H(2)O}(n) (SB2+ = N,N '-ethylenebis(5-trimethylammoniomethylsalicylideneiminate) based on orbitally degenerate cyanidometallates [Os-III(CN)(6)](3-) (1) and [Ru-III(CN)(6)](3-) (2) and Mn-III Schiff base complex were synthesized and characterized structurally and magnetically. Their crystal structures consist of ...
Abstract
Two novel 1D heterobimetallic compounds {[Mn-III(SB2+)M-III(CN)(6)]center dot 4H(2)O}(n) (SB2+ = N,N '-ethylenebis(5-trimethylammoniomethylsalicylideneiminate) based on orbitally degenerate cyanidometallates [Os-III(CN)(6)](3-) (1) and [Ru-III(CN)(6)](3-) (2) and Mn-III Schiff base complex were synthesized and characterized structurally and magnetically. Their crystal structures consist of electrically neutral, well-isolated chains composed of alternating [M-III(CN)(6)](3-) anions and square planar [Mn-III(SB2+)](3+) cations bridged by cyanide groups. These -ion magnetic anisotropy of Mn-III centers. These results indicate that the presence of compounds exhibit single-chain magnet (SCM) behavior with the energy barriers of Delta tau(1)/k(B) = 73 K, Delta tau(2)/k(B) = 41.5 K (1) and Delta tau(1)/k(B) = 51 K, Delta tau(2) = 27 K (2). Blocking temperatures of T-B = 2.8, 2.1 K and magnetic hysteresis with coercive fields (at 1.8 K) of 8000, 1600 Oe were found for 1 and 2, respectively. Theoretical analysis of the magnetic data reveals that their single-chain magnet behavior is a product of a complicated interplay of extremely anisotropic triaxial exchange interactions in M-III(4d/5d)-CN-Mn-III fragments: -J(x)S(M)(x)S(Mn)(x)-J(y)S(M)(y)S(Mn)(y)-J(z)S(M)(z)S(Mn)(z), with opposite sign of exchange parameters J(x) = -22, J(y) = +28, J(z) = -26 cm(-1) and J(x) = -18, J(y) = +20, J(z) = -18 cm(-1) in 1 and 2, respectively) and single orbitally degenerate [Os-III(CN)(6)](3-) and [Ru-III(CN)(6)](3-) spin units with unquenched orbital angular momentum in the chain compounds 1 and 2 leads to a peculiar regime of slow magnetic relaxation, which is beyond the scope of the conventional Glaubers's 1D Ising model and anisotropic Heisenberg model.
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