Hard–soft interactions in early transition-metal thioether macrocyclic chemistry: spectroscopic and extended X-ray absorption fine structure studies on chromium(III) thioether complexes

Abstract

A series of chromium(III) thioether macrocyclic complexes of the form [CrX ₃ ([9]aneS ₃ )], [CrX ₃ ([10]aneS ₃ )], [(CrX ₃ ) ₂ (µ-[18]aneS ₆ )] (X = Cl or Br), [CrX ₂ (14]aneS ₄ )]PF ₆ and [CrX ₂ ([16]aneS ₄ )]PF ₆ (X = Cl, Br or I) ([9]aneS ₃ = 1,4,7-trithiacyclononane, [10]aneS ₃ = 1,4,7-trithiacyclodecane, [18]aneS ₆ = 1,4,7,10,13,16-hexathiacyclooctadecane, [14]aneS ₄ = 1,4,8,11-tetrathiacyclotetradecane, [16]aneS ₄ = 1,5,9,13-tetrathiacyclohexadecane) has been prepared and characterised by IR and UV/VIS spectroscopy, microanalyses, and in some cases electrospray mass spectrometry. Chromium K-edge extended X-ray absorption fine structure studies have provided information on the Cr–X and Cr–S bond-length distributions in a selection of these compounds, and these, together with the relatively low Dq values derived from UV/VIS spectroscopy, confirm rather weak chromium(III)–thioether interactions in these unusual species involving hard metal and soft ligand combinations.