Secondary metal-ligand cationic subunits {ML}ⁿ⁺ as structural determinants in the oxovanadium/phenylphosphonate/{ML}ⁿ⁺ system, where {ML} is a Cu²⁺/organonitrogen moiety

The hydrothermal reactions of CuSO₄·5H₂O, Na₃VO₄, phenylphosphonic acid and the appropriate organonitrogen ligand yield a series of materials of the oxovanadium/ phenylphosphonate/Cu(II)-ligand family. The structural influences of the organonitrogen ligand are most pronounced in the dimensionality of the material. Thus, [{Cu(phen)}VO(O₃PC₆H₅) ₂]·0.5 H₂O (1) is one-dimensional; [{Cu ₂(bpytrz)(H₂O)}VO(O₃PC₆H ₅)₂(HO₃PC₆H₅)] (2) (bpytrz 5 3,5-di-2-pyridyl-1,2,4-triazolate) is two-dimensional, and [{Cu(4,4′-bpy)}_0.5VO₂(O₃PC ₆H₅)] (3) is three-dimensional. When the phenylphosphonate component is replaced by phenyl-1,2-diphosphonate, the three-dimensional material [{Cu(4,4′-bpy)}VO₂(HO₃PC₆H ₄PO₃)] (4) is obtained. In contrast to the structure of 3 which exhibits a three-dimensional Cu-V-P-O substructure which encapsulates the {Cu₂(bpy)}⁴⁺ unit, 4 exhibits the more common "pillared" layer structure with Cu-V-P-O networks buttressed by the 4,4′-bipyridyl groups. When the starting materials that gave 4 are reacted at 200°C rather than 120°C, the copper phase [{Cu(4,4′-bpy) _0.5}{Cu(H₂O)}(O₃PC₆H ₄PO₃)]·H₂O (5) is obtained. Compound 5 exhibits a "pillared" layer structure with a Cu-P-O network exhibiting embedded binuclear copper(II) sites.