Self-assembly of water cluster in iron(III) oxalate-bridged complexes

The synthesis and crystal structural characterization of the compound of formula {Fe^II(phen)₃]₂Fe₂^IIIox₅]}·11H₂O (1) has been reported. The most interesting feature of the solid state structure of 1 consists in the occurrence of decanuclear water clusters made up of self-assembled cyclic hexameric water clusters with a quasi-planar conformation, unclosed trinuclear clusters and individual water molecules. The decanuclear water clusters are connected to the host lattices via an extensive net of strong hydrogen bonds that finally lead to an extended 3D supramolecular organization, wherein hexameric water clusters interconnected with dodecameric hybrid water–O_oxalate clusters can be identified. The comparison of this supramolecular architecture with that found in the already known compound of formula Fe(bpm)₃]₂Fe₂(ox)₅]·8H₂O (2) allows some preliminary observations on the design and control of water cluster nuclearity and conformation.