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