Isopolyoxometalates of Antimony: Arylstibonic Acids [H8(RSb)12O28] and Derived Dodecanuclear Polyoxostibonates [M2H10-x(RSb)12O30]x-, M = Na or K

Electrospray ionization mass spectrometry shows arylstibonic acids, p-XC6H4SbO3H2 (X = methyl, nitro, or chloro), and 1-naphthylstibonic acid exist in MeCN as dodecanuclear aggregates [H-8(RSb)(12)O-28]. With KOH or NaOH these form polyoxometalate ions [M2H8(RSb)(12)O-30](2-) (M = K or Na) with a hexagonal antiprismatic array of the Sb atoms, as shown by X-ray crystallographic structures for three new examples. There is one firmly encapsulated 10-coordinate M+ ion within an inorganic 12-crown-6 moiety {Sb6O6} in the hexagonal channel and one six-coordinate M+.