Neutral diiron(iii) complexes with Fe2(μ-E)2 (E = O, S, Se) core structures: reactivity of an iron(i) dimer towards chalcogens

Abstract

Three neutral bis(μ-chalcogenido)diiron(III) complexes, [{(N,N′-Pipiso)Fe(μ-E)}₂] (Pipiso⁻ = [(DipN)₂C(cis-2,6-Me₂NC₅H₈)]⁻, (Dip = C₆H₃Prⁱ₂-2,6; E = O, S or Se) have been prepared by reactions of the iron(I) dimer [{(μ-N,N′-Pipiso)Fe}₂] with O₂, S₈ or Se_∞. Treating the μ-selenido compound [{(N,N′-Pipiso)Fe(μ-Se)}₂] with O₂ cleanly generated its μ-oxo counterpart, [{(N,N′-Pipiso)Fe(μ-O)}₂]. X-ray crystallographic analyses of the compounds showed them to possess Fe₂(μ-E)₂ core structures with distorted square planar (E = O) or tetrahedral (E = S or Se) iron coordination geometries. Magnetic, ⁵⁷Fe Mössbauer spectroscopic and computational studies indicate medium to strong antiferromagnetic coupling between the two high-spin Fe^III ions in all three compounds.