Synthesis and Structural Characterization of ... - Jacobs University

Chapter 5
Published Results
Transition-metal-containing POMs are usually prepared in a one-pot reaction of transition
metal ions (e.g., Cu 2+ , Fe 3+ ) with lacunary polytungstate precursors. In particular, the class of
copper-containing POMs is very rich with respect to the number of Cu 2+ ions and the shape of
the magnetic cluster, for example, [Cu 3 (H 2 O) 3 (α-XW 9 O 33 ) 2 ] n– (n = 12, X = As III , Sb III ; n = 10,
X = Se IV , Te IV ), 6 [Cu 4 (H 2 O) 2 (B--XW 9 O 34 ) 2 ] n– (X = P V , As V , n = 10; X = Si IV , n = 12), 7
[Cu 4 K 2 (H 2 O) 8 (α-AsW 9 O 33 ) 2 ] n– , 8 [Cu 5 (OH) 4 (H 2 O) 2 (A-α-SiW 9 O 33 ) 2 ] 10- , 9
[{(SiW 9 O 34 )(SiW 9 O 33 (OH))(Cu(OH)) 6 Cu} 2 X] 23– (X = Cl, Br), 10 and
[Cu 20 Cl(OH) 24 (H 2 O) 12 (P 8 W 48 O 184 )] 25– . 11
However, the number of transition-metal-containing tungstogermanates is still limited.
The subclass of organic-inorganic hybrid tungstogermanates includes a handful of structures.
The group of Yang prepared [Ni 4 (Hdap) 2 (B-α-HGeW 9 O 34 ) 2 ] 8– (dap = 1,2-diaminopropane), 12
[Cu 5 (2,2-bpy) 6 -(H 2 O)][B-β-GeW 8 O 31 ] and {[Cu 5 (2,2-bpy) 5 (H 2 O)][B-α-GeW 9 O 34 ]} 2 (2,2bpy
= 2,2-bipyridine). 13 On the other hand, Niu et al. reported the copper-containing species
[Cu(DMF) 4 (α-GeW 12 O 40 ) 2 ] 6– (DMF = N,N-dimethylformamide), 14 {[Cu(phen)(µ 2 -
CH 3 COO) 2 Cu(phen)(H 2 O)] 2 [Ge 2 W 23 CuO 80 ]} 8– (phen = phenanthroline), 15 and
[Cu(en) 2 (H 2 O)] 2 {[Cu 4 (GeW 9 O 34 ) 2 ][Cu(en) 2 ]} 3– . 16
Our group has contributed several tungstogermanates with different incorporated or
grafted transition metals: [(RuC 6 H 6 ) 2 GeW 9 O 34 ] 6– , 17 [Ru(dmso) 3 (H 2 O)GeW 11 O 39 ] 6− , 18
[{Ru(C 6 H 6 )(H 2 O)}{Ru(C 6 H 6 )}(γ-GeW 10 O 36 )] 4– , 19 [Fe 6 (OH) 3 (A-α-GeW 9 O 34 (OH) 3 ) 2 ] 11– , 20
K(H 2 O)(β-Fe 2 GeW 10 O 37 (OH))(γ-GeW 10 O 36 )] 12– and [{β-Fe 2 GeW 10 O 37 (OH) 2 } 2 ] 12– , 21 and the
Weakley-type dimers [M 4 (H 2 O) 2 (B--GeW 9 O 34 ) 2 ] 12– (M = Mn 2+ , Cu 2+ , Zn 2+ , Cd 2+ ). 22
Other transition-metal-containing tungstogermanates include
[Cu 10 (H 2 O) 2 (N 3 ) 4 (GeW 9 O 34 ) 2 (GeW 8 O 31 ) 2 ] 24– , 23 [Y(GeW 11 O 39 )(H 2 O) 2 ] 5– , 24
[Ti 6 (OH) 3 (GeW 9 O 37 ) 2 ] 11– , 25 and the open Wells-Dawson structure [{Co(H 2 O)}(µ-
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