A New Family of Sandwich-Type Polytungstophosphates Containing Two Types of Metals in the Central Belt: M'2M2(PW9O34)212- (M' = Na or Li, M = Mn2+, Co2+, Ni2+, and Zn2+)

A new family of sandwich-type potytungstophosphates containing two different types of metals in the central belt, M'2M(PW9O34)212- (M' = Na or Li, M = Mn2+, CO2+ Ni2+, and Th2+) have been synthesized and characterized by infrared spectroscopy, 31P solution NMR spectroscopy, and elemental analysis. Compounds Na2CO2(PW9O34)212- (Na2Co2), Na2Ni2(PW9O34)212- (Na2Ni2), L2(PW9O34)212- (Li2NI2), Na2Mn2(PW9O34)212- (Na2Mn2), and U2Zn2+ (PW9O34)212- (Li2Zn2) were characterized by X-ray crystallography. All these compounds have similar structures, in which two transibon-metal ions and two alkali metal ions (sodium or lithium) are sandwiched between two [B-α-PW9O34]9- units; the transibon and alkali metals reside in the internal and external (solvent exposed) positions of the central belt, respectively. By adding UCI to aqueous solutions of compounds Na2M2, lithium-sodium exchanges in the external beit positions are observed by 31P solution NMR spectroscopy and X-ray crystallography. Magnetic measurements indicate ferromagnetic exchange interactions between the two Ni2+ ions in Na2Nr2 at 10-300 K and the two CO2+ ions in Na2Co2 at 6-30 K. In contrast, Na2Mn2 exhibits an antiferromagnetic interaction between the Mn2+ ions at 2-50 K. [ABSTRACT FROM AUTHOR]