2D and 3D Anilato-Based Heterometallic M(I)M(III) Lattices: The Missing Link

The similar bis-bidentate coordination mode of oxalato and anilato-based ligands is exploited here to create the first examples of 2D and 3D heterometallic lattices based on anilato ligands combining M­(I) and a M­(III) ions, phases already observed with oxalato but unknown with anilato-type ligands. These lattices are prepared with alkaline metal ions and magnetic chiral tris­(anilato)­metalate molecular building blocks: [MIII(C6O4X2)3]3– (MIII = Fe and Cr; X = Cl and Br; (C6O4X2)2– = dianion of the 3,6-disubstituted derivatives of 2,5-dihydroxy-1,4-benzoquinone, H4C6O4). The new compounds include two very similar 2D lattices formulated as (PBu3Me)2[NaCr­(C6O4Br2)3] (1) and (PPh3Et)2[KFe­(C6O4Cl2)3]­(dmf)2 (2), both presenting hexagonal [MIMIII(C6O4X2)3]2– honeycomb layers with (PBu3Me)+ in 1 or (PPh3Et)+ and dmf in 2 inserted between them. Minor modifications in the synthetic conditions yield the novel 3D lattice (NEt3Me)­[Na­(dmf)]­[NaFe­(C6O4Cl2)3] (3), in which hexagonal layers analogous to 1 and 2 are interconnected through Na+ cations, and (NBu3Me)2[NaCr­(C6O4Br2)3] (4), the first heterometallic 3D lattice based on anilato ligands. This compound presents two interlocked chiral 3D (10,3) lattices with opposite chiralities. Attempts to prepare 4 in larger quantities result in the 2D polymorph of compound 4 (4′). Magnetic properties of compounds 1, 3, and 4′ are reported, and in all cases we observe, as expected, paramagnetic behaviors that can be satisfactorily reproduced with simple monomer models including a zero field splitting (ZFS) of the corresponding S = 3/2 for Cr­(III) in 1 and 4′ or S = 5/2 for Fe­(III) in 3.本研究利用草酸根合配体（oxalato）与苯胺醌型配体（anilato）相似的双双齿配位模式，构建了首例基于苯胺醌型配体、同时包含一价金属（M(I)）与三价金属（M(III)）离子的二维（2D）与三维（3D）异金属晶格；此类物相此前仅在草酸根合配体体系中被观测到，而苯胺醌型配体体系中尚未见报道。此类晶格以碱金属离子与具有磁性的手性三(苯胺醌合)金属酸盐分子构筑单元[MIII(C6O4X2)3]3–（其中MIII为Fe或Cr；X为Cl或Br；(C6O4X2)2–为2,5-二羟基-1,4-苯醌（H4C6O4）的3,6-二取代衍生物的二价阴离子）制备得到。所合成的新型化合物包含两种结构高度相似的二维晶格：(PBu3Me)2[NaCr(C6O4Br2)3]（1）与(PPh3Et)2[KFe(C6O4Cl2)3]·(dmf)2（2）。二者均呈现六方[MIMIII(C6O4X2)3]2–蜂窝状层结构，其中1的层间填充三丁基甲基鏻阳离子（PBu3Me+），2的层间则填充三苯基乙基鏻阳离子（PPh3Et+）与N,N-二甲基甲酰胺（dmf）。对合成条件进行小幅调整，可得到新型三维晶格(NEt3Me)[Na(dmf)][NaFe(C6O4Cl2)3]（3）——其层结构与1、2的六方层类似，通过Na+阳离子相互连接——以及(NBu3Me)2[NaCr(C6O4Br2)3]（4），后者是首例基于苯胺醌型配体的异金属三维晶格。化合物4包含两个互为对映异构、相互穿插的手性3D(10,3)晶格。尝试放大制备4时，得到了其2D晶型4'。本文报道了化合物1、3与4'的磁学性质；正如预期，三者均表现出顺磁行为，可通过简单的单体模型进行良好拟合：其中1与4'中的Cr(III)对应自旋多重度S=3/2的零场分裂（zero field splitting, ZFS），3中的Fe(III)则对应S=5/2的零场分裂。