Iron complexes with polythioether ligands: the relation of unusually large Mössbauer quadrupole splittings to structure

Abstract

New thioether complexes of iron(II) have been prepared: [Fe(MeCN)₂([14]aneS₄)][FeI₄]([14]aneS₄= 1,4,8,11-tetrathiacyclotetradecane), [Fe([16]aneS₄)]X₂([16]aneS₄= 1,5,9,13-tetrathiacyclohexadecane) and [Fe(MeSCH₂CH₂SMe)₂X₂](X = Br or I). The crystal structure of [Fe([16]aneS₄)]I₂ and Mössbauer properties of [Fe([16]aneS₄)]X₂ are consistent with their formulation as unusual square-planar, high-spin iron(II) complexes. This peculiarity is ascribed to the size of [16]aneS₄ which forces longer than normal Fe–S bonds on the system.