Weakley sandwich-type anion in organic–inorganic hybrid compound with 3D framework

Reaction of Na2WO4·2H2O, GeO2, Cu(Ac)2·H2O and H4EGTA in conventional conditions results in formation of a new compound, (H3O)4Cu(H2O)6[K6(H2O)17Cu2(EGTA)(H2O)2{Cu4(H2O)2(B-α-GeW9O34)2}]·9H2O (1) (EGTA = ethyleneglycol-bis-(2-aminoethylether)-N,N,N′,N′-tetraacetate tetraanion). Its crystal structure was determined with X-ray diffraction method. The in situ synthesized [Cu4(H2O)2(B-α-GeW9O34)2]12 − has the typical Weakley sandwich structure and acts as an eleven-dentate ligand linking nine K+ ions and two Cu2 + ions. All Cu2 + ions are in an elongated octahedral environment. Two Cu2 + ions are chelated by EGTA from two ends and coordinated by terminal oxygen atoms of [Cu4(H2O)2(B-α-GeW9O34)2]12 −, forming a chain CuEGTA-Cu4(H2O)2(GeW9O34)2. K+ ions connect the chains into a complicated three dimensional framework. The magnetic measurement shows that 1 exhibits antiferromagnetic property.

Graphical abstractWeakley sandwich-type anion [Cu4(H2O)2(B-α-GeW9O34)2]12 − was in situ synthesized and acts as an eleven-dentate ligand linking nine K+ ions and two Cu2 + ions in (H3O)4Cu(H2O)6[K6(H2O)17Cu2(EGTA)(H2O)2{Cu4(H2O)2(B-α-GeW9O34)2}]·9H2O (1), which is the highest dentate number for the anion. [Cu4(H2O)2(B-α-GeW9O34)2]12 −, Cu2 + ions and EGTA are assembled into a complicated 3D framework with antiferromagnetic property.Figure optionsDownload full-size imageDownload as PowerPoint slideHighlights► [Cu4(H2O)2(B-α-GeW9O34)2]12 − was in situ synthesized in presence of H4EGTA. ► [Cu4(H2O)2(B-α-GeW9O34)2]12 − acts as an eleven-dentate ligand in the compound. ► The chelating ligand EGTA plays an important role in constructing 3D framework. ► 1 is first structurally-defined compound of [Cu4(H2O)2(GeW9O34)2]12 − and Cu-EGTA.