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

Abstract

Hydrothermal reactions of V 2O 5, 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 [V x O y (H m O 3PC 6H 4PO 3H p ) 3]. Compound 1, [H 3N(CH 2) 4NH 3][V 2O 4(O 3PC 6H 4PO 3)], 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, [H 3N(CH 2) 2NH 3][V 2O 2(O 3PC 6H 4PO 3H) 2] and [H 2pip][V 2O 2(O 3PC 6H 4PO 3H) 2] (H 2pip = 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 [H 3N(CH 2) 7NH 3] 2[V 3O 4(O 3PC 6H 4PO 3) 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, [H 2dabco][V 2F 3O 2(O 3PC 6H 4PO 3H)]·H 2O, is also three-dimensional with oxyfluoro-vanadium(IV) chains linked through the diphosphonate ligands into a framework structure with void spacers to accommodate the {H 2dabco} 2+ cations (dabco = diamino bicyclo octane). The magnetic properties of 2– 5 reflect the structural characteristics of the materials.