Redox chemistry of ruthenium ions in mono-substituted Keggin tungstophosphate: a new synthetic extension for ruthenium derivatives based on [PW11O39Ru(VI)N](4.).

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(IV)Cl} 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(Ru[triple bond, length as m-dash]N)] 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(IV)Cl] ((n-Bu4N)4[3]). These complexes are fully characterized by (1)H NMR and (31)P NMR spectroscopy, infrared spectroscopy, cyclic voltammetry, elemental analysis, thermogravimetric-differential thermal analysis, electrospray ionization mass spectrometry (ESI-MS) and X-ray photoelectron spectroscopy (XPS).