Solid state coordination chemistry of the oxofluorovanadium–diphosphonate system in the presence of Cu(II)–tetrapyridylpyrazine complex cations: The crystal structures of [{Cu2(tpyprz)(H2O)2}V4FO8(HO3PCH2PO3)2], [{Cu2(tpyprz)(H2O)2}V4F6O6(O3PCH2CH2PO3)],

The hydrothermal reactions of V2O5, Cu(CH3CO2)2·H2O, tetrapyridylpyrazine (tpyprz), HF and the appropriate diphosphonic acid yielded a series of compounds of the {Cu2(tpyprz)}4+/VxOyFzn-/{O3P(CH2)nPO3}4- family of materials. The structure of [{Cu2(tpyprz)(H2O)2}V4F6O6(HO3PCH2PO3)2] (1) is one-dimensional, constructed from mixed valence {V3VVIVFO8(HO3PCH2PO3)2}4- clusters linked through {Cu2(tpyprz)(H2O)2}4+ rods. The two-dimensional [{Cu2(tpyprz)(H2O)2}V4F6O6(O3PCH2CH2PO3)] (2) is constructed from {V4F6O6(O3PCH2CH2PO3)}n4n- chains crosslinked by {Cu2(tpyprz))(H2O)2}4+ rods; mixed valence {V2VV2IVF6O6(O3PCH2CH2PO3)}4- clusters are embedded in the network. Compound 3, [Cu2(tpyprz){HO3P(CH2)3PO3H}][V2F2O5], consists of [Cu2(tpyprz){HO3P(CH2)3PO3H}]n2n+ chains and isolated {V2F2O5}2− anions. Structures 1–3 are compared to the structures of the analogous series {Cu2(bisterpy)}4+/VxOyFzn-/{O3P(CH2)nPO3}4-, where bisterpy is 2,2′:4′:4″:2″,2‴-quaterpyridine, 6′,6″-di-2-pyridinyl. The temperature-dependent magnetic susceptibilities of 2 and 3 are also discussed.

Graphical abstractHydrothermal reactions have been exploited in the preparation of a series of bimetallic oxides constructed from {Cu2(tpyprz)}4+ and oxyfluorovanadium organophosphonate components. A view of the two-dimensional structure of the mixed valence [{Cu2(tpyprz)(H2O)2}V4F6O6(O3PCH2CH2PO3)] is provided.Figure optionsDownload full-size imageDownload as PowerPoint slide