Sandwich polyoxometalates structure

FIGURE 16.1 Structure of the [WZn3(ZnW9034)2] sandwich polyoxometalate anion. 

Transition metals substituted polyoxometalates are obtained starting from vacant or lacunary POMs. The latter are derived from the saturated parent POM, through formal loss of one or more MOe octahedral units. Such complexes present several coordinatively unsaturated oxygen atoms, which surround the defect and form a polydentate site, able to coordinate a multitude of transition metals, M . Fundamental modes of coordination of the transition metals are in pocket and out of pocket , the latter including sandwich-like structures and metal oxide cluster stabilization, depending both on the dimensions of M and on the stoichiometic ratio between M and the vacant units. " ... 

The structure of [(Y0H2)3(C03)(A-a-PW9034)2]" [25]. (Reprinted with permission from T.M. Anderson, W.A. Neiwert, and C.L. HiU, Yttrinm polyoxometalates. Synthesis and characterization of a carbonate-encapsulated sandwich-type complex, Inorganic Chemistry, 42, no. 26, 8600-8602 (Figure 1), 2003. 2003 American Chemical Society.)... 

Figure 5.1 General structure of the Keggin-type (a) and sandwich-type (b) transition metal substituted polyoxometalates (TMSPs) used in catalysis W (green) O (red) heteroatom X (yellow) transition metal M (pink). See insert for color representation of the figure.)...

FIGURE 31. An assembly of [Cu(H20)5(Ci2H2406)2] sandwiches and polyoxome-talate anions [MogOi9] in the crystal structure of [Cu(H20)5(Ci2H2405)2][Mo50i9], showing the molecular clipping of the sandwiches by polyoxometalate anions. (Reprinted with permission from ref. 61.)... 

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