title: A new family of sandwich-type polytungstophosphates containing two types of metals in the central belt: M'2M2(PW9O34)(2)(12-) (M' = Na or Li, M = Mn2+, Co2+, Ni2+, and Zn2+).
abstract: A new family of sandwich-type polytungstophosphates containing two different types of metals in the central belt, M'(2)M(2)(PW(9)O(34))(2)(12-) (M' = Na or Li, M = Mn(2+), Co(2+), Ni(2+), and Zn(2+)), have been synthesized and characterized by infrared spectroscopy, (31)P solution NMR spectroscopy, and elemental analysis. Compounds Na(2)Co(2)(PW(9)O(34))(2)(12-) (Na2Co2), Na(2)Ni(2)(PW(9)O(34))(2)(12-) (Na2Ni2), Li(2)Ni(2)(PW(9)O(34))(2)(12-) (Li2Ni2), Na(2)Mn(2)(PW(9)O(34))(2)(12-) (Na2Mn2), and Li(2)Zn(2)(PW(9)O(34))(2)(12-) (Li2Zn2) were characterized by X-ray crystallography. All these compounds have similar structures, in which two transition-metal ions and two alkali metal ions (sodium or lithium) are sandwiched between two [B-alpha-PW(9)O(34)](9-) units; the transition and alkali metals reside in the internal and external (solvent exposed) positions of the central belt, respectively. By adding LiCl to aqueous solutions of compounds Na2M2, lithium-sodium exchanges in the external belt positions are observed by (31)P solution NMR spectroscopy and X-ray crystallography. Magnetic measurements indicate ferromagnetic exchange interactions between the two Ni(2+) ions in Na2Ni2 at 10-300 K and the two Co(2+) ions in Na2Co2 at 6-30 K. In contrast, Na2Mn2 exhibits an antiferromagnetic interaction between the Mn(2+) ions at 2-50 K.
authors.affiliation: Department of Chemistry, Emory University, 1515 Dickey Drive, Atlanta, Georgia 30322, USA.
authors.forename: Yu
authors.initials: Y
authors.lastname: Hou
authors.forename: Lin
authors.initials: L
authors.lastname: Xu
authors.forename: Morgan J
authors.initials: MJ
authors.lastname: Cichon
authors.forename: Sheri
authors.initials: S
authors.lastname: Lense
authors.forename: Kenneth I
authors.initials: KI
authors.lastname: Hardcastle
authors.forename: Craig L
authors.initials: CL
authors.lastname: Hill
mesh_terms: D008670:Metals / Q000737:chemistry*; D010710:Phosphates / Q000737:chemistry*; D011108:Polymers / Q000138:chemical synthesis / Q000737:chemistry*; D013696:Temperature; D014414:Tungsten / Q000737:chemistry*
chemical_list: D008670:Metals; D010710:Phosphates; D011108:Polymers; D014414:Tungsten