Synthesis, isolation and spectroscopic characterization of Dawson polyoxotungstate-supported, organometallic complex, [{(C6H6)Ru}P2W15V3O62]7−: The two positional isomers

The Dawson polyoxotungstate (POM)-based, organometallic ruthenium(II) complex, [{(C6H6)Ru}P2W15V3O62]7−, was synthesized as two materials, i.e. 1 · 2Bu4NCl and 1 · 1Bu4NCl (1 = (Bu4N)7[{(C6H6)Ru}P2W15V3O62]), which contained two positional isomers a and b as major or minor species. In isomer a with the overall Cs symmetry, the (C6H6)Ru2+ group was supported on one vanadium(V) octahedral site (two V–O–V bridging oxygens and one Odouble bond; length as m-dashV terminal oxygen) of the three edge-shared vanadium(V) octahedra (V3 site, B-site) in the Dawson POM-support [1,2,3-P2W15V3O62]9−, whereas in the other isomer b with the overall C3v symmetry, the (C6H6)Ru2+ group was supported on the center of the V3 site in the Dawson POM-support. Material 1 · 2Bu4NCl was prepared by a stoichiometric reaction in CH2Cl2 at ambient temperature of the Dawson POM-support (Bu4N)9[1,2,3-P2W15V3O62] with the precursor [(C6H6)RuCl2]2, whereas material 1 · 1Bu4NCl was prepared by a stoichiometric reaction in CH3CN under refluxing conditions. The temperature-varied 31P NMR spectra revealed that b was thermodynamically more stable thana.