New Sb12 and Sb14 Polyoxometalate Frameworks Derived from Arylstibonic Acids: [LiH3(p-MeC6H4Sb)12O28]4- and [BaH10(p-MeC6H4Sb)14O34]

The lithium salt of p-tolylstibonic acid contains the anion [LiH3(p-MeC6H4Sb)(12)O-28](4-), in which the Li+ is fully enclosed within an {Sb12O28} cage with gamma Keggin ion geometry; the idealized overall formula is Li-5[LiH3(p-MeC6H4Sb)(12)O-28]Br center dot 18H(2)O. In contrast, Ba2+ induces the formation of the unprecedented {Sb14O34} bowl-shaped polyoxostibonate [BaH10(p-MeC6H4Sb)(14)O-34]center dot 4H(2)O. Compounds were characterized by single-crystal X-ray crystallography and by ESI-MS.