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

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journal contribution
posted on 01.06.2015, 00:00 by Samia Benmansour, Cristina Vallés-García, Patricia Gómez-Claramunt, Guillermo Mínguez Espallargas, Carlos J. Gómez-García
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.