Synthesis and characterization of copper-, zinc-, manganese-, and cobalt-substituted dimeric heteropolyanions, [(alpha-XW9O33)(2)M-3(H2O)(3)](n-) (n=12, X = As-III, Sb-III, m = Cu2+, Zn2+; n=10, X = Se-IV, Te-IV, M = Cu2+) and [(alpha-AsW9O33)(2)WO(H2O)M-2(H2O)(2)](10-) (M = Zn2+, Mn2+, Co2+)

Interaction of the lacunary [alpha -XW9O33](9-) (X = As-III, Sb-III) with C u2+ and Zn2+ ions in neutral, aqueous medium leads to the formation of dime ric polyoxoanions, [(alpha -XW9O33)(2)M-3(H2O)(3)](12-) (M = Cu2+, Zn2+; X = As-III, Sb-III), in high yield. The selenium and tellurium analogues of t he copper-containing heteropolyanions are also reported: [(alpha -XW9O33)(2 )Cu-3(H2O)(3)](10-) (X = Se-IV, Te-IV). The polyanions consist of two [alph a -XW9O33] units joined by three equivalent Cu2+ (X = As, Sb, Se, Te) or Zn 2+ (X = As, Sb) ions. All copper and zinc ions have one terminal water mole cule resulting in square-pyramidal coordination geometry. Therefore, the ti tle anions have idealized DY, symmetry. The space between the three transit ion metal ions is occupied by three sodium ions (M = Cu2+, Zn2+: X = As-III , Sb-III) or potassium ions (M = Cu2+; X = Se-IV, Te-IV) leading to a centr al belt of six metal atoms alternating in position. Reaction of [alpha -AsW 9O33](9-) with Zn2+, Co2+, and Mn2+ ions in acidic medium (pH = 4-5) result s in the same structural type but with a lower degree of transition-metal s ubstitution, [(alpha -AsW9O33)(2)-WO(H2O)M-2(H2O)(2)](10-) (M = Zn2+, Co2+, Mn2+). All nine compounds are characterized by single-crystal X-ray diffra ction, IR spectroscopy, and elemental analysis. The solution properties of [(alpha -XW9O33)(2)Zn-3(H2O)(3)](12-) (X = As-III Sb-III) were also studied by W-183-NMR spectroscopy.