Synthesis and Structural Characterization of ... - Jacobs University

Chapter 3
Unpublished Results
In polyanions 15–17 the Ln 3+ ion is bound to the two SbW 9 subunits via three -oxo
bridges, two bridges to one SbW 9 unit and one bridge to the other unit through one WO 6
octahedral of the rotated triad (yellow in Figure 3.29). The lanthanide ion has three terminal
aqua ligands. The coordination sphere of the lanthanide ion is completed through a Ln–O–W’
bridge, where W’ belongs to a neighbouring polyanion, leading to a dimer formation in the
solid state (see Figure 3.30).
Figure 3.30. Polyhedral representation of 15–17 forming a dimer in the solid state. The color
code is as follows: WO 6 octahedra (red), Sb (green), Ln (blue), H 2 O (pink).
We checked for possible protonation of polyanions 15–17 by bond valence sum (BVS)
calculations, 12 one monoprotonated oxygen was identified in the fac-WO 6 octahedral, (BVS ~
0.99) (grey ball in Figure 3.19) and no additional protonation sites besides the terminal aqua
ligands described above were identified. This results in an OH group for 15–17 and a total
charge of –10 for the polyanions. It is noteworthy that the resulting protonation of one of the
three terminal oxy ligand groups is most preferable to obey the Lipscomb rule.
The di-lanthanide(III) polyanions [Ln 2 (H 2 O) 6 Sb 2 W 20 O 70 )] 8−
(Ln = Yb (18), Lu(19),
Y(20)) were synthesized under mild, conventional conditions by interaction of the sodium salt
of the trilacunary SbW 9 with Ln 3+ ions in aqueous acidic (pH = 5) medium. Interaction of
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