Synthesis and characterization of novel heteropolytungstoarsenate containing lanthanum (LaAs4W40O140)25- and its derivatives (LaAs4W40O140M2)n-

Summary A novel polyanionic ligand (LaAs₄W₄₀O₁₄₀)^25- and its derivatives (LaAs₄W₄₀O₁₄₀M₂)^n- (M = Mn²⁺, Fe²⁺, Fe³⁺, Cr³⁺, Co²⁺, Ni²⁺, Cu²⁺ or Zn²⁺) have been prepared and characterized by elemental analyses, i.r., u.v.-vis. and emission spectra, ¹⁸³W-n.m.r. and polarography. There is evidence that lanthanide occupies the central S1 site, whereas the transition metal cations occupy the S2 site, in the complexes.