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: [M^III(C₆O₄X₂)₃]^3– (M^III = 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 [M^IM^III(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.