Patent Number: 053645685
Section: claims

1. A method of encapsulating a cation, comprising (i) contacting, in an aqueous solution, an anion of formula (I): EQU [DA.sub.5 M.sub.30-x O.sub.110-x (M'L).sub.x ].sup.m- (I) 2. The method of claim 1, wherein D is Na, x is 0, A is P, and m is 14. 3. In a method of reprocessing spent nuclear reactor fuel, comprising separating a cation from an aqueous solution comprising said cation, the improvement being that said separating comprises contacting, in an aqueous solution, an anion of formula (I): EQU [DA.sub.5 M.sub.30-x O.sub.110-x (M'L).sub.x ].sup.m- (I) 4. The method of claim 3, wherein D is Na, x is 0, A is P, and m is 14. 5. The method of claim 3, wherein said separating further comprises precipitating said anion of formula (II) in the form of an insoluble salt. 6. A composition of matter of the formula (II): EQU [ZA.sub.5 M.sub.30-x O.sub.110-x (M'L).sub.x ].sup.(m+1-n)- (II) 7. The composition of matter of claim 6, wherein x is 0 or 1, M' is V, L is O.sup.2-, and m is 14 or 15. 8. The composition of matter of claim 6, wherein x is 0 and m is 14. 9. The composition of matter of claim 6, wherein x is 1, m' is V, L is O, and m is 15. 10. The composition of matter of claim 6, which is in the form of a water-soluble salt. 11. The composition of matter of claim 6, which is in the form of a water-insoluble salt. 12. The composition of matter of claim 6, which is in the form of a potassium ion salt. 13. The composition of matter of claim 6, wherein x is 0, A is P, and m is 14. 14. A composition of matter of formula (Ia): EQU [DA'.sub.5 M.sub.30-x O.sub.110-x (M'L).sub.x ].sup.m- (I) (a) every occurrence of A' is not P when x is 0; and  (b) every occurrence of A' is not P, M' is not V, and L is not O, when x is 1. 15. The composition of matter of claim 14, which is in the form of a water-soluble salt. 16. The composition of matter of claim 14, which is in the form of a sodium ion salt. 17. The method of claim 1, wherein said separating comprises extracting said anion of formula (II) into an organic solvent by means of a phase transfer agent. 18. The method of claim 1, wherein said separating comprises precipitating said anion of formula (II). 19. The method of claim 18, wherein said anion of formula (II) is precipitated as a potassium salt, a cesium salt, or a NR.sub.4.sup.+ salt, wherein R is methyl, ethyl, or n-propyl. 20. The method of claim 1, wherein said anion of formula (I) is selected from the group consisting of [NaP.sub.5 W.sub.29 VO.sub.110 ].sup.16- and [NaP.sub.5 W.sub.30 O.sub.110 ].sup.14-. 21. The method of claim 3, wherein said anion of formula (I) is selected from the group consisting of [NaP.sub.5 W.sub.29 VO.sub.110 ].sup.16- and [NaP.sub.5 W.sub.30 O.sub.110 ].sup.14-.