Titanium(IV) iodide complexes with phosphine and arsine donor ligands and the crystal structures of the iron(II)/(III) redox pair [FeI 2{ o-C 6H 4(AsMe 2) 2} 2] 0/+

Abstract

Red-brown [TiI 4{ o-C 6H 4(PMe 2) 2}] and [TiI 4{ o-C 6H 4(AsMe 2) 2}] have been prepared from the ligands and TiI 4 in a 1:1 molar ratio in anhydrous CH 2Cl 2. They have been characterised by analysis, IR, 1H and 31P{ 1H} NMR and UV–Visible spectroscopy as appropriate and have six-coordinate ( cis) octahedral geometries. Investigation of the yellow or fawn products from reactions of TiI 4 and the ligands in a 1:2 molar ratio, and suggested in the literature to be bis(ligand)-Ti(IV) complexes, have shown that these are mixtures containing iodinated and oxidised ligands, but do not contain Ti(IV)–iodide complexes. The crystal structures of two iron–diarsine complexes [FeI 2{ o-C 6H 4(AsMe 2) 2} 2] and [FeI 2{ o-C 6H 4(AsMe 2) 2} 2]I 3 · 2CH 2Cl 2 arising from iron iodide impurities in one commercial sample of TiI 4 are reported. The complexes constitute a redox pair and the iron(III) complex is the first pseudo-octahedral iron(III) iodide complex to be structurally characterised.