Hexa-μ-Acetato-chlorido(μ-N,2-dioxodobenzene-1-carboximidato)-μ3oxido-Tetrairon(III)-water (1/1) and hexa-μ-Acetato-(μ-N,2-dioxodobenzene-1-carboximidato)fluorido-μ3 oxido-Tripyridinetetrairon(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 salicylhydroxamic acid (H3shi), acetic acid (HOAc), and the appropriate ferric halide salt. The compounds crystallize as solvates, where 1-F has one pyridine molecule that is disordered about a twofold axis and one water molecule with an occupancy of 0.24 (2); and 1-Cl has one water molecule 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 intermolecular interactions involving the different halides. The two molecules 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 octahedral 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.