Leiden Institute of Chemistry, Gorlaeus Laboratories, Leiden University, PO Box 95022300 RA, Leiden, The Netherlands.
Dalton Trans. 2011 Sep 7;40(33):8407-13. doi: 10.1039/c1dt10310e. Epub 2011 Jul 4.
Two new d-f cyanido-bridged 1D assemblies [RE(pzam)(3)(H(2)O)Mo(CN)(8)]·H(2)O (RE = Sm(III), Er(III)) were synthesized and their magneto-structural properties have been studied by field-dependent magnetization and specific heat measurements at low temperatures (≥0.3 K). Below ≈ 10 K the ground state of both the Sm(III) and Er(III) ions is found to be a Kramers doublet with effective spin S = 1/2. From analyses of the low-temperature magnetic specific heat and magnetization the exchange coupling between these RE(III) effective spins and the Mo(v) spins S = 1/2 along the structural chains has been determined. It is found to be antiferromagnetic, with J(∥)/k(B) = -2.6 K and Ising-Heisenberg symmetry of the interaction (J(∥)/J(⊥) = 0.3) for RE = Sm(III), whereas the compound with RE = Er(III) behaves as a pure XY chain, with J(⊥)/k(B) = -1.0 K. For the compound [Sm(pzam)(3)(H(2)O)Mo(CN)(8)]·H(2)O a small λ-type anomaly in the specific heat is observed at about 0.6 K, which is ascribed to a transition to long-range magnetic ordering induced by weak interchain interactions of dipolar origin. No evidence for 3D interchain magnetic ordering is found in the Er(III) analogue.
两个新的 d-f 氰根桥联一维组装体 [RE(pzam)(3)(H(2)O)Mo(CN)(8)]·H(2)O (RE = Sm(III), Er(III)) 被合成，并通过磁场相关的磁化率和低温下的比热测量研究了它们的磁结构性质（≥0.3 K）。在 ≈ 10 K 以下，Sm(III)和 Er(III)离子的基态被发现是一个具有有效自旋 S = 1/2 的 Kramers 双重态。通过低温磁比热和磁化率的分析，确定了这些 RE(III)有效自旋与 Mo(v)自旋 S = 1/2 之间沿结构链的交换耦合。发现其为反铁磁耦合，Sm(III)的 J(∥)/k(B) = -2.6 K，相互作用的 Ising-Heisenberg 对称性（J(∥)/J(⊥) = 0.3），而具有 RE = Er(III)的化合物表现为纯 XY 链，J(⊥)/k(B) = -1.0 K。对于化合物 [Sm(pzam)(3)(H(2)O)Mo(CN)(8)]·H(2)O，在约 0.6 K 处观察到比热中的小 λ 型异常，这归因于由源于偶极的弱链间相互作用引起的长程磁有序转变。在 Er(III)类似物中没有发现 3D 链间磁有序的证据。
