Redox chemistry of ruthenium ions in mono-substituted Keggin tungstophosphate: a new synthetic extension for ruthenium derivatives based on [PW11O39RuVIN]4−

Abstract

We herein report the synthesis and characterization of a series of ruthenium-substituted Keggin-type heteropolytungstates containing {Ru^II(NO)}, {Ru^III(H₂O)} or {Ru^IVCl} species. Although anionic [PW₁₁O₃₉Ru^II(NO)]⁴⁻ (1) and [PW₁₁O₃₉Ru^III(H₂O)]⁴⁻ (2) are known, a new synthetic method for the preparation of (n-Bu₄N)₄[1] and (n-Bu₄N)₄[2] is developed in this paper. Treatment of (n-Bu₄N)₄[XW₁₁O₃₉(RuN)] with Me₃NO afforded the ruthenium(II) nitrosyl complex (n-Bu₄N)₄[1] in almost quantitative yield. Photolysis of (n-Bu₄N)₄[1] solution in CH₃CN/H₂O gives (n-Bu₄N)₄[2], which is readily oxidized by PhICl₂ to yield the Ru^IV complex (n-Bu₄N)₄[PW₁₁O₃₉Ru^IVCl] ((n-Bu₄N)₄[3]). These complexes are fully characterized by ¹H NMR and ³¹P NMR spectroscopy, infrared spectroscopy, cyclic voltammetry, elemental analysis, thermogravimetric-differential thermal analysis, electrospray ionization mass spectrometry (ESI-MS) and X-ray photoelectron spectroscopy (XPS).