Preparation and structural characterization of mono-Ru-substituted α₂-Dawson-type phosphotungstate with a carbonyl ligand and other Ru(CO)-substituted heteropolytungstates

In our previous article (Dalton Trans. 2008, 6692-6698) we reported that hydrothermal reaction of a mono-lacunary Keggin-type silicotungstate, [SiW₁₁O₃₉]^8-, and Ru(acac)₃ (acac: acetylacetonate) for 5-24 h produced a mono-Ru-substituted Keggin-type silicotungstate with a terminal aqua ligand, [SiW₁₁O₃₉Ru^III(H₂O)]^5-, which was further converted into a carbonyl (CO) derivative, [SiW₁₁O₃₉Ru^II(CO)]^6-, by increasing the reaction time for several days. Here, reactions of Ru(acac)₃ with other mono-lacunary heteropolytungstates for the formation of other mono-Ru(CO)-substituted heteropolytungstates, including Keggin derivatives, [GeW₁₁O₃₉Ru^II(CO)]^6- and [PW₁₁O₃₉Ru^II(CO)]^5-, and Dawson-type phosphotungstates, [α₁-P₂W₁₇O₆₁Ru^II(CO)]^8- and [α₂-P₂W₁₇O₆₁Ru^II(CO)]^8-, are presented. The desired α₂-isomer of Dawson-type phosphotungstate, [α₂-P₂W₁₇O₆₁Ru^II(CO)]^8-, was produced in high purity and was fully characterized by CV, ³¹P NMR, ¹³C NMR, IR, UV/Vis, elemental analysis, mass spectroscopy, TG-DTA, TPD-MS, and single-crystal structure analysis. On the other hand, Keggin-type complexes, [GeW₁₁O₃₉Ru^II(CO)]^6- and [PW₁₁O₃₉Ru^II(CO)]^5-, were formed together with their aqua derivatives, [GeW₁₁O₃₉Ru^III(H₂O)]^5- and [PW₁₁O₃₉Ru^III(H₂O)]^4-, respectively, and the α₁-isomer of Dawson-type phosphotungstate, [α₁-P₂W₁₇O₆₁Ru^II(CO)]^8-, was produced together with the α₂-derivative, as confirmed by CV, IR, mass spectroscopy, and ³¹P NMR spectroscopy.