Extended coordination frameworks incorporating heterobimetallic squares

Abstract

The molecular structure of aluminium and iron(III) complexes with 3-phenyl and 3-(4-pyridyl) (HL) substituted acetylacetonate ligands is appreciably distorted. For AlL₃ and FeL₃ this shows that the orientation of the side pyridyl-N donor atoms lone pairs is about 90 and 135° which favours the assembly of heterobimetallic square patterns in Al(Fe)L₃ complexes with metal ions. This was employed for the modular construction of semi-regular heterobimetallic networks, in which the pyridyldiketonate ligands bridge pairs of Fe(Al)/Cd(Co) metal ions and support the structure of 1D and 2D coordination polymers. The unprecedented 2D structure of [Cd{AlL₃}(CH₃OH){NO₃}₂]·2CHCl₃ and Cd{AlL₃}(CH₃OH)Br₂]·2CHCl₃·2CH₃OH is based upon plane tiling by a set of heterobimetallic squares and octagons, while [Cd{FeL₃}₂(NO₃)₂]·2H₂O and [Co{AlL₃}₂Cl₂]·4CHCl₃·2CH₃OH are 1D polymers and exist as chains of heterobimetallic squares sharing opposite vertices.