Stabilization of high-valence ruthenium with silicotungstate ligands: preparation, structural characterization, and redox studies of ruthenium(III)-substituted α-Keggin-type silicotungstates with pyridine ligands, [SiW11O39Ru(III)(Py)]5-.

Ruthenium(III)-substituted α-Keggin-type silicotungstates with pyridine-based ligands, [SiW(11)O(39)Ru(III)(Py)](5-), (Py: pyridine (1), 4-pyridine-carboxylic acid (2), 4,4'-bipyridine (3), 4-pyridine-acetamide (4), and 4-pyridine-methanol (5)) were prepared by reacting [SiW(11)O(39)Ru(III)(H(2)O)](5-) with the pyridine derivatives in water at 80 °C and then isolated as their hydrated cesium salts. These compounds were characterized using cyclic voltammetry (CV), UV/Vis, IR, and (1)H NMR spectroscopy, elemental analysis, titration, and X-ray absorption near-edge structure (XANES) analysis (Ru K-edge and L(3)-edge). Single-crystal X-ray analysis of compounds 2, 3, and 4 revealed that Ru(III) was incorporated in the α-Keggin framework and was coordinated by pyridine derivatives through a Ru-N bond.

Carbonyl-ruthenium substituted alpha-Keggin-tungstosilicate, [alpha-SiW(11)O(39)Ru(II)(CO)](6-): synthesis, structure, redox studies and reactivity.

The carbonyl-ruthenium substituted undecatungstosilicate [alpha-SiW(11)O(39)Ru(II)(CO)](6-) () was isolated as a caesium salt and successfully characterized by using (183)W and (13)C NMR, elemental analysis, IR, UV-vis and cyclic voltammetry (CV). Polyanion represents the first example of a metal-carbonyl moiety being fully incorporated into the polyoxometalate (POM). As a result, the Ru(CO) moiety became redox active and was reversibly oxidized to the one-electron ruthenium(iii) derivative, [alpha-SiW(11)O(39)Ru(III)(CO)](5-).