Peacock-Weakley anion

LANTHANIDE AND ACTINIDE CATION LINKERS Mixed Ligand Peacock-Weakley Anions... 

Peacock-Weakley anions, exemplified by a-[PWu039] and a2-[P2W 706i]. Both of these are stable in aqueous solution and this stability allows the straightforward determination of conditional formation constants. Pi and P2 for the 1 1 and 1 2 complexes respectively (see Table 1 for examples)... 

Figure 8. Polyhedral representation of the syn conformation of the C2-symmetric Peacock-Weakley type anions [M(a2-X2Wi706i)2] > showing the square-antiprismatic coordination environment of the heteroatom M.

The first systematic studies of polyoxometalate—rare-earth complexes were published in 1971 (Peacock and Weakley, 1971a, 1971b). Two classes of polytungstate complexes were described and these can now be seen to have common structural features. The complexes of Y, La, Ce(III and IV), Pr, Nd, Sm, Ho, Er, and Yb in which R W = 1 10 were readily formed by reaction of WO - with the appropriate rare-earth salt, but are stable only within the pH range 5.5-8.5. More recent 183W-NMR studies (Inoue et al., 2003) indicate that in solution the anions containing the heaviest R (Tm, Yb and Lu) are partially decomposed. 

Two isomers [al-P2Wi706i] ° and [a2-P2Wi706i] ° can be derived from the parent Wells-Dawson anion [a-P2Wi8062] by removal of a belt or cap W = Od unit, respectively. Complexes of RE ions with a lacunary [a-P2Wi706i] ° anion were first reported by Peacock and Weakley in 1971, which is now known as [RE(a2-P2Wi706i)2]" - The complex of the al isomer, [RE(al-P2Wi706i)]" , has also been prepared, although it could not be isolated. Until... 

The lacunary anions [PWnOsg] ", [SiWn039] " and (a2-) [P2Wi706i] °" were first shown to form complexes with a variety of lanthanide cations (Ln POM =1 1 and 1 2) by Peacock and Weakley in 1971.[41] At that time only the 1 2 complexes could be isolated, and the ai isomer of [P2Wi706i] ° had not been discovered. The first actinide (tetravalent Th, U) analogs of the Peacock-... 

Anions of type 2 above were first synthesized by Peacock and Weakley in 1971, and the first reports of crystal structures of such (1 2) complexes ([U (GeWu039)2] and... 

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