An organosilyl derivative of trivacant tungstophosphate. Synthesis, characterization and crystal structure determination of α-A-[NBu4]3[PW9O34(C2H5SiO)3(C2H5Si)]

In the presence of NBu₄ⁿBr acting as phase-transfer reagent, organosilicon trichloride C₂H₅SiCl₃ reacts in acetonitrile with the trivacant tungstophosphate sodium salt β-A-Na₈HPW₉O₃₄]·24H₂O to give hybrid organosilyl polyoxotungstate derivative α-A-NBu₄ⁿ]₃PW₉O₃₄(C₂H₅SiO)₃(C₂H₅Si)]. X-ray single crystal structural analysis indicates that the title compound is monoclinic, space group Cc, with lattice constants a=26.828(5), b=22.459(5), c=17.517(4) Å, β=103.19(3)°, V=10,276(4) Å³, Z=4, R=0.0462. According to the result of X-ray single crystal diffraction and chemical analysis, the hybrid polyanion consists of one α-A-PW₉O₃₄]⁹⁻ framework on which are grafted simultaneously three RSiO groups through six Si-O-W bridge bonds, each of which is attached to the fourth RSi group through three Si-O-Si bridge bonds. The hybrid polyanion becomes a partial saturated, closed cage structure and also has an assembly of virtual C_3V symmetry.