Hexa-μ-acetato-chlorido-(μ-N,2-dioxodo-benzene-1-carboximidato)-μ3-oxido-tetra-iron(III)-water (1/1) and hexa-μ-acetato-(μ-N,2-dioxodo-benzene-1-carboximidato)fluorido-μ3-oxido-tri-pyridine-tetra-iron(III)-pyridine-water (1/1/0.24).

Abstract

The title compounds, [Fe4(C2H3O2)6(C7H4O3)FO(C5H5N)3]·C5H5N·0.24H2O (1-F) and [Fe4(C2H3O2)6(C7H4O3)ClO(C5H5N)3]·H2O (1-Cl) were synthesized using a self-assembly reaction in methanol and pyridine with stoichiometric addition of salicyl-hydroxamic acid (H3shi), acetic acid (HOAc), and the appropriate ferric halide salt. The compounds crystallize as solvates, where 1-F has one pyridine mol-ecule that is disordered about a twofold axis and one water mol-ecule with an occupancy of 0.24 (2); and 1-Cl has one water mol-ecule that is disordered over two sites with occupancies of 0.71 (1) and 0.29 (1). The space groups for each analog differ as 1-F crystallizes in Fdd2 while 1-Cl crystallizes in P21. The difference in packing is due to changes in the inter-molecular inter-actions involving the different halides. The two mol-ecules are mostly isostructural, differing only by the torsion of the pyrine ligands and slight orientation changes in the acetate ligands. All of the iron(III) ions are in six-coordinate octa-hedral ligand field geometries but each one exhibits a unique coordination environment with various numbers of O (four to six) and N (nought to two) atom donors. Bond-valence sums confirm each iron is trivalent. The hydroximate ligand is bound to three iron(III) ions using a fused chelate motif similar to those in metallacrown compounds.