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A-Dawson anions

One of the lacunary derivatives of the a-Dawson anion forms crystals of composition, K28Li5H7PgW4gOig4 92H20 ( P8W48, (46)) with the cyclic structure shown in Figure 38. A tetramer of P2W12 groups leads to the D f, symmetry of the structure of the PgW48 anion. The crystal structure reveals that the central cavity of the anion contains a number of potassium cations. [Pg.24]

Electrochemistry of a New family of Wells-Dawson Anions SemivacantTungstophosphates and Arsenates [H4XWi8062] (X = P... [Pg.608]

B) Wells-Dawson (a-X2Wig062 ) anions (taken from Ref 1). [Pg.612]

FIGURE 14 Some multivacant lacunary structures derived from Keggin and Dawson anions, (a) A-a-[PW9 034]9- (b) B-a-[PW9034]9-, (c) a-[P2Wi5 0 56]12- (d) y-[SiW10O36]8-. [Pg.356]

The anion [Ce4(0H)2(H20)9(P2Wi6059)2]14 (Figure 24) is isolated in good yield from reaction of Ce(NC>3)3 with Ki2H2P2Wi2048-nH20/ a hexavacant derivative of the Wells-Dawson anion U WisCfe]6-, and Na2W04. The anion has... [Pg.361]

Figure 9). The Dawson anions are formed spontaneously in molybdophosphate and -arsenate solutions of the appropriate stoichiometry and acidity, but the tungstates are formed slowly in solutions with a large excess of phosphate or arsenate. Several structural isomers (a, p, etc.) are known, especially for the tungstates. These involve rotation of the edge-shared triad groups at the ends of the anion, and/or rotation of the two halfunits. Further (positional) isomerism has been demonstrated for mixed-addenda species such as o -[ P04 2 Wi2Mo6054] . Figure 9). The Dawson anions are formed spontaneously in molybdophosphate and -arsenate solutions of the appropriate stoichiometry and acidity, but the tungstates are formed slowly in solutions with a large excess of phosphate or arsenate. Several structural isomers (a, p, etc.) are known, especially for the tungstates. These involve rotation of the edge-shared triad groups at the ends of the anion, and/or rotation of the two halfunits. Further (positional) isomerism has been demonstrated for mixed-addenda species such as o -[ P04 2 Wi2Mo6054] .
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... [Pg.194]

P2Wi6059] ° anion is a divacant derivative of a Wells-Dawson [a-P2Wi8062] anion, with the lacunae in adjacent belt (al) sites on either side of the anion s belt. In the complex, the four central cerium ions are linked by two X3-OH(Ce3), one X2-H20(Ce2), and four (1,3-0(W,Ce2). There are two distinct cerium coordination environments. The two cerium atoms... [Pg.200]

Keggin anion [SiWn039] by a monovacant Wells-Dawson anion [a2-P2Wi706i] , has also been reported [48]. [Pg.207]

The [P8W480i84] anion shows a cyclic cluster structure constructed by four P2W12O48 units derived from a Wells-Dawson anion by removal of six adjacent W06 octahedra. In the complex RE4(H20)28[KcP8W480i84(H4W40i2)2RE2(H20)io] (RE = La, Ce, Pr,... [Pg.216]

The commonest lacunary polytungstates are derived from three plenary tungstate structures the C Lindqvist ) hexatungstate, [WgOig] the Keggin anion, typically a-[PWi204o] and the Wells-Dawson anion, typically a-[P2Wis062] -. [Pg.346]

Figure 6. Three lacunary deivatives of the Wells-Dawson anion a-[P2Wi80g2] (a) ap [P2Wi70gi] ° (b) a2-[P2Wi70gi] ° (c) a-[P2Wi505g] ... Figure 6. Three lacunary deivatives of the Wells-Dawson anion a-[P2Wi80g2] (a) ap [P2Wi70gi] ° (b) a2-[P2Wi70gi] ° (c) a-[P2Wi505g] ...
Figure 8 Numbering scheme for the a isomers of the Keggin and Wells-Dawson anions. The numbering is retained for the /3-isomer of the Keggin anion with the rotated triad containing atoms 10, 11, and 12. Figure 8 Numbering scheme for the a isomers of the Keggin and Wells-Dawson anions. The numbering is retained for the /3-isomer of the Keggin anion with the rotated triad containing atoms 10, 11, and 12.
Electrochemistry of a New Family of Wells-Dawson Anions Semivacant Tungstophosphates and Arsenates [H4XWi8O6zf- (X=PorAs)... [Pg.660]

A. Ostuni, Lanthanide and actinide complexes of the lacunary Wells-Dawson anions synthesis, structure... [Pg.26]


See other pages where A-Dawson anions is mentioned: [Pg.660]    [Pg.661]    [Pg.661]    [Pg.17]    [Pg.762]    [Pg.762]    [Pg.762]    [Pg.796]    [Pg.797]    [Pg.798]    [Pg.660]    [Pg.661]    [Pg.661]    [Pg.17]    [Pg.762]    [Pg.762]    [Pg.762]    [Pg.796]    [Pg.797]    [Pg.798]    [Pg.312]    [Pg.633]    [Pg.668]    [Pg.44]    [Pg.1040]    [Pg.1040]    [Pg.1041]    [Pg.121]    [Pg.196]    [Pg.200]    [Pg.275]    [Pg.104]    [Pg.354]    [Pg.649]    [Pg.650]    [Pg.661]    [Pg.666]    [Pg.667]    [Pg.608]    [Pg.633]    [Pg.668]   
See also in sourсe #XX -- [ Pg.796 ]




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A Anionic

Dawson

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