Abstract
The oxalato-titanium(IV)-containing, dimeric 18-tungsto-2-phosphate [Ti-8(C2O4)(8)P2W18O76(H2O)(4)](18-) (1) and the 32-tungsto-4-phosphate [Ti-6(C2O4)(4)P4W32O124](20-) (2) are formed upon reaction of the oxalato-titanium complex [TiO(C2O4)(2)](2-) with the trilacunary Keggin precursor [A-alpha-PW9O34](9-) and the hexalacunary Wells-Dawson precursor [H2P2W12O48](12-), respectively. Polyanion 1 consists of two {PW9} units encapsulating eight titanium centers and connected to each other via two Ti-O-Ti bridges, and crystallizes as a mixed potassium-sodium-lithium salt in the triclinic space group . Polyanion 2 comprises two {P2W16} units containing each two titanium atoms, and the two half-units are connected via two titanium atoms decorated by two oxalate groups each, and crystallizes as a mixed potassium-lithium salt in the rhombohedral space group . Polyanions 1 and 2 were characterized in the solid state by single-crystal XRD, FT-IR, and TGA, whereas polyanion 2 was also investigated by P-31 and W-183 NMR.