The synthesis and properties of tris(diphosphine)- and bis(triphosphine)-chromium (III) cations and analogues with arsenic and sulphur donor ligands

Abstract

The reaction of [Cr(thf)₆][BF₄]₃(thf = tetrahydrofuran) with bidentate (L²) and tridentate (L³) ligands in thf produces [Cr(L²)₃][BF₄]₃[L²= Ph₂PCH₂CH₂PPh₂, Me₂PCH₂CH₂PMe₂, o-C₆H₄(PMe₂)₂, o-C₆H₄(AsMe₂)₂, cis-Ph₂AsCHCHAsPh₂, or cis-MeSCHCHSMe] and [Cr(L³)₂][BF₄]₃[L³= PhP(CH₂CH₂PPh₂)₂, McAs(CH₂CH₂CH₂AsMe₂)₂, MeC(CH₂PPh₂)₃, MeC(CH₂AsMe₂)₃, or S(CH₂CH₂CH₂SMe)₂] respectively. On the basis of their i.r. and electronic spectra all contain octahedral chromium(III) CrE₆³⁺(E = P, As, or S) type cations. [Cr(Me₂PCH₂CH₂PMe₂)₃][BF₄]₃ undergoes a reversible electrochemical one-electron reduction in dimethyl sulphoxide solution.