Syntheses, characterization and magnetic properties of two novel inorganic–organic tungstoferrites, [FeIII4(H2O)2(B-α-FeIIIW9O34)2]10−

Interaction of the lacunary [α-SbW9O33]9– with Fe3+ in the presence of organic amines under hydrothermal conditions yields two novel inorganic–organic hybrid tungstoferrites [dapH2]3[enH2][enH]Na[Fe4(H2O)2(FeW9O34)2]·7H2O (dap=1,2-diaminopropane, en=ethylenediamine) (1) and [dapH2]5[Fe4(H2O)2(FeW9O34)2]·11H2O (2), which have been characterized by IR, elemental analysis, UV–Vis, TG and single-crystal X-ray diffraction. Both 1 and 2 consist of two [B-α-FeIIIW9O34]11− units joined by a rhomb-like tetranuclear iron cluster. Interestingly, 1 displays a new example of 1D chain-like architecture, in which adjacent [Fe4(FeW9O34)2]10– anions are interconnected by two unusual W–O–Fe bridges. Meanwhile, the neighboring chains are further assembled by Na+ ions, forming the 2D extended network. 2 exhibits a discrete dimeric TMSP structure constructed from two trivacant [B-α-FeIIIW9O34]11− subunits encapsulating a rhomb-like tetranuclear iron cluster with five isolated diprotoned dap molecules. Magnetic measurements indicate that antiferromagnetic exchange interactions are dominant in the hexanuclear {Fe6O22} clusters in 1 and 2.