A Direct Three‐Component Reaction for the Isolation of a Nonanuclear Iron(III) Phosphonate

The synthesis, structure, and magnetism of a nonanuclear iron(III) phosphonate, [Fe9III(μ3‐O)4(O3PC5H9)3(O2CCMe3)13]·(EtOH)0.5·(Et2O)0.5 (1), is described. Compound 1 was obtained in the direct reaction of anhydrous ferric chloride, cyclopentylphosphonic acid, and pivalic acid in the presence of triethylamine. Compound 1 possesses a distorted icosahedral structure; nine of the vertices are occupied by FeIII, whereas three others are occupied by the phosphorus atoms of the cyclopentylphosphonate ligand. Mössbauer spectroscopy of 1 confirms the presence of high‐spin FeIII. Low‐temperature magnetic studies reveal the presence of strong antiferromagnetic coupling between the Fe3+ ions.