The hydrothermal chemistry of the copper-organonitrogen ligand/vanadium oxide/aromatic phosphonate system has been studied. Not only was HF required to induce crystallization, but product composition was highly dependent on the HF/V ratio of the reactions. At relatively low concentrations of HF/V of 6:1, materials of the Cu(II)-ligand/V_xO_y/organophosphonate type were observed, namely, [{Cu(phen)}₂V₂O₅(O₃PC₆H₄PO₃)] (1), [Cu(phen)VO₂(HO₃PC₆H₄PO₃)] (2), [{Cu(terpy)}₂V₂O₅(O₃PC₆H₄PO₃)] (3), [{Cu(phen)(H₂O)}VO₂(HO₃PC₆H₄PO₃)] (6), [{Cu(phen)}VO₂(HO₃PC₆H₄PO₃)] (7a and 7b), [Cu(C₅H₄NCO₂)₂V₂O₄(HO₃PC₆H₄POH₃)] (8), [Cu(bpy)VO₂ {(HO₃P)₃C₆H₃}]·1.5H₂O (12·1.5H₂O), [{Cu(bpy)}₂V₃O₇{(O₃P)₂C₆H₃PO₃H}] (13) and [Cu(phen)V₃O₆(H₂O){(O₃P)₂C₆H₃(PO₃H)}] (14). When the HF concentration was raised, materials incorporating fluoride anion were observed; that is, compounds of the Cu(II)-ligand/V_xO_yF_z/organophosphonate type: [{Cu(bpa)}₂VO₂F(H₂O)(O₃PC₆H₄PO₃)]·H₂O (4), [{Cu(bpa)}₂V₂O₄F₂(O₃PC₆H₄PO₃)] (5), [{Cu(bpy)}₂V₂O₄F₂(O₃PC₆H₄PO₃)] (9), [{Cu(terpy)}₂V₃O₆F(HO₃PC₆H₄PO₃)₂] (10), [{Cu(bpa)}₂V₂O₄F₂(O₃PC₆H₄PO₃)] (11). At HF/V concentrations of 25:1 or greater, vanadium free products, Cu(II) ligand/organophosphonate, were obtained: [Cu(C₅H₄NCO₂)₂(H₂O₃PC₆H₄PO₃H₂)]·H₂O (15·H₂O), [Cu(C₅H₄NCO₂)₂(H₂O₃PC₆H₄PO₃H₂)] (16), [Cu(bpy)(H₂O){(HO₃P)₂C₆H₃(PO₃H₂)}] (17), [Cu(bpy){(HO₃P)₂C₆H₃(PO₃H₂)}]·H₂O (18·H₂O), [Cu(phen){(H₂O₃P)C₆H₃(PO₃H)₂}]·2H₂O (19·2H₂O) and [Cu(bpa){H₂O₃PC₆H₃(PO₃H)₂}]·H₂O (20·H₂O). The structural chemistry is unusually diverse with the Cu(II) ligand/V_xO_y/organophosphonate series exhibiting one-, two- and three-dimensional structures with a variety of copper-vanadate and vanadophosphonate substructures. The structural chemistry is discussed in relation to other examples of materials of the Cu(II) ligand/V_xO_y/organophosphonate and Cu(II) ligand/V_xO_yF_z/organophosphonate families.