Synthesis, Crystal Structure, and Magnetic Studies of One-Dimensional Cyano-Bridged Ln3+−Cr3+ Complexes with bpy as a Blocking Ligand

The reaction of Ln(NO3)3·aq with K3[Cr(CN)6] and 2,2‘-bipyridine (bpy) in a water/ethanol solution led to two families
of complexes:  4 one-dimensional (1D) complexes of the formula trans-[Cr(CN)4(μ-CN)2Ln(H2O)3(bpy)2]n·4nH2O·3.5nbpy (Ln3+ = La, Ce, Pr, and Nd) and 10 1D complexes of the formula trans-[Cr(CN)4(μ-CN)2Ln(H2O)4(bpy)]n·3.5nH2O·1.5nbpy (Ln3+ = Nd, Sm, Eu, Tb, Dy, Ho, Er, Tm, Yb, and Lu). The structures for the fourteen complexes
[LaCr]n (1), [CeCr]n (2), [PrCr]n (3), [NdCr]n (4), [NdCr]n (4‘), [SmCr]n (5), [EuCr]n (6), [TbCr]n (7), [DyCr]n (8), [HoCr]n
(9), [ErCr]n (10), [TmCr]n (11), [YbCr]n (12), and [LuCr]n (13) have been solved. Complexes 1−4 crystallize in the
orthorhombic space group Pbam and are isomorphous; complexes 4‘−13 crystallize in the triclinic space group PĪ
and are isomorphous. The X-ray structural characterization of complexes 1−4 shows the presence of a discrete
decameric water cluster built around a cyclic hexameric core stabilized by the solid-state structure, which represents
another new mode of association of water molecules. The Ln3+−Cr3+ magnetic interaction is negligible in 6 and 12,
antiferromagnetic in 2, 4‘, 7, 8, 9, 10, and 11, and unresolved for 3. The complex 5 is a ferrimagnet because its
magnetic studies suggest the onset of a very weak ferromagnetic three-dimensional ordering.

在乙醇/水溶液中，硝酸镧（Ln(NO3)3·aq）与三氰铬酸钾（K3[Cr(CN)6]）及2,2'-联吡啶（bpy）发生反应，生成了两种系列的配合物：一类为一维（1D）配合物，其化学式为trans-[Cr(CN)4(μ-CN)2Ln(H2O)3(bpy)2]n·4nH2O·3.5nbpy（其中Ln3+ = La, Ce, Pr, 和 Nd），共4种；另一类也为一维（1D）配合物，其化学式为trans-[Cr(CN)4(μ-CN)2Ln(H2O)4(bpy)]n·3.5nH2O·1.5nbpy（其中Ln3+ = Nd, Sm, Eu, Tb, Dy, Ho, Er, Tm, Yb, 和 Lu），共10种。十四种配合物[LaCr]n（1）、[CeCr]n（2）、[PrCr]n（3）、[NdCr]n（4）、[NdCr]n（4‘）、[SmCr]n（5）、[EuCr]n（6）、[TbCr]n（7）、[DyCr]n（8）、[HoCr]n（9）、[ErCr]n（10）、[TmCr]n（11）、[YbCr]n（12）和[LuCr]n（13）的结构已得到解析。其中，1-4号配合物结晶于正交晶系Pbam空间群，且彼此同质；4‘-13号配合物结晶于三斜晶系PĪ空间群，亦彼此同质。对1-4号配合物的X射线结构表征揭示了围绕环状六元核心的离散十元水簇的存在，该核心由固态结构稳定，这代表了水分子结合的新模式。在6和12号配合物中，Ln3+−Cr3+磁性相互作用可忽略不计；在2、4‘、7、8、9、10和11号配合物中，表现为反铁磁性；3号配合物的磁性未解析。5号配合物为铁磁性物质，因为其磁性研究显示出现了极其微弱的铁磁性三维有序性。