Nonanuclear Heterometal Five-Layer Sandwich-Type Polyoxometalate.

A new nonanuclear heterometal five-layer sandwich silicotungstate [H2N(CH3)2]6H5NaK{[NaMn8O6(OAc)6][A-α-SiW9O34]2}·34H2O (1) has been made under hydrothermal reactions of MnCl2·4H2O, KMnO4, trivacant [A-α-SiW9O34]10- {SiW9} fragment, and [H2N(CH3)2]·Cl in NaOAc-HOAc buffer (pH = 4.8). The polyoxoanion of 1 is a sandwich architecture, in which the nonanuclear heterometal cluster [NaMn8O6(OAc)6]7+ made of two triangular pyramid clusters [Mn4O3(OAc)3]3+ {Mn4} via a hexacoordinate antitrigonal prism Na+ linkage is encapsulated by two trivacant fragments of {SiW9}. Furthermore, magnetic measurements of compound 1 reveal the existence of antiferromagnetic exchange interactions between the metal centers.