Solid state coordination chemistry of the oxovanadium-diphosphonate system: Structural consequences of aryl tethers on materials of the type cation/VxOy/diphos, where cation = organoammonium and diphos = 1,4-phenyldiphosphonic acid

Hydrothermal reactions of V2O5, 1,4-phenyldiphosphonic acid and an appropriate organoamine, in the presence of HF as solubilizer, were exploited to prepare a series of materials of the general type [organoammonium cation]n[VxOy(HmO3PC6H4PO3Hp)3]. Compound 1, [H3N(CH2)4NH3][V2O4(O3PC6H4PO3)], exhibits a one-dimensional V–P–O substructure, linked through the phenyl tethers of the ligand into a { V 2 O 4 ( O 3 PC 6 H 4 PO 3 ) } n 2 n - layer. Compound 1 is a unique example of a V(V)-diphosphonate phase. Compounds 2 and 3, [H3N(CH2)2NH3][V2O2(O3PC6H4PO3H)2] and [H2pip][V2O2(O3PC6H4PO3H)2] (H2pip = piperazinium), exhibit identical two dimensional { V 2 O 2 ( O 3 PC 6 H 4 PO 3 H ) 2 } n 2 n - substructures, constructed from { V 2 O 2 ( O 3 PR ) 2 ( HO 3 PR ) 2 } n 2 n - ribbons connected through the phenyl tethers of the ligands. The three-dimensional framework of [H3N(CH2)7NH3]2[V3O4(O3PC6H4PO3)2] (4) consists of V–P–O layers characterized by trinuclear V(IV)-oxide subunits and 9 and 12 polyhedral connect rings; the layers are buttressed by the phenyl spacers to provide the typical “pillared” layer structure common to metal diphosphonate materials. Compound 5, [H2dabco][V2F3O2(O3PC6H4PO3H)]·H2O, is also three-dimensional with oxyfluoro-vanadium(IV) chains linked through the diphosphonate ligands into a framework structure with void spacers to accommodate the {H2dabco}2+ cations (dabco = diamino bicyclo octane). The magnetic properties of 2–5 reflect the structural characteristics of the materials.