Synthesis and Structural Characterization of ... - Jacobs University

Chapter 1
Introduction
[Gd 8 As 12 W 124 O 432 (H 2 O) 22 ] 60– ({Gd 8 As 12 W 124 }) from the reaction of Gd 3+ ions with the
dilacunary polyanion precursor [As 2 W 19 O 67 (H 2 O)] 14– . 50 The polyanion {Gd 8 As 12 W 124 }
exhibits C i point group symmetry and comprises two identical [Gd 4 As 6 W 62 O 216 (H 2 O) 11 ] 30–
subunits linked by two Gd–O–W bridges. Each subunit is composed of six trilacunary
tungstoarsenates(III) (α-As III W 9 O 33 ) 9− {AsW 9 } building blocks and two {Gd 2 W 4 } fragments.
The gadolinium ions are octacoordinate with two terminal aqua ligands. Finally, the largest
molecular polytungstate to date is the cerium containing arsenotungstate
[Ce 16 As 12 W 148 O 524 (H 2 O) 36 ] 76− , reported in 1997 by Pope and coworkers, and containing 16
ceriums and 148 tungstens. 51
Our group has also been working on lanthanide-containing heteropolytungstates. 52 We
have reported the ytterbium-containing tungstoarsenate [YbAs 2 W 20 O 68 (H 2 O) 3 ] 7−
resulting
from the interaction of the monolacunary [As 2 W 20 O 68 (H 2 O)] 10− with Yb 3+ ions in acidic
aqueous medium. The polyanion consists of two (α-As III W 9 O 33 ) 9− fragments connected by a
V-shaped (H 2 O)Yb(OW(H 2 O)) 2 fragment (Figure 1.13). 52a
Figure 1.13 Combined polyhedral/ball-and-stick representation of [YbAs 2 W 20 O 68 (H 2 O) 3 ] 7− .
Red octahedra: WO 6 , green balls: As, red ball: O, blue ball: Yb.
30