Effect of the central metal on coordination of 1,10-phenanthroline-5,6-dione in Keggin-based hybrid compounds

Two new Keggin-based hybrid compounds, [Cu₂(pdon)₃][PMo^VI ₁₁Mo^VO₄₀]·3H₂O (1) and [Mn₂Cl(H₂O)₂(pdon)₄][PMo₁₂O₄₀]·2H₂O (2) (pdon = l, l0-phenanthroline-5,6-dione) (pdon), were synthesized under hydrothermal conditions. By using different metal ions and tuning the ratio of metal to ligand, pdon shows different coordination modes. In compound 1, pdon with three kinds of coordination modes link Cu^II ions to form a 1D wave chain and Keggin-type polyanions [PMo^VI ₁₁Mo^VO₄₀]^4? fringe this 1D chain; hydrogen bonding interactions extend these 1D chains into a 2D supramolecular network. Compound 2 exhibits a discrete structure, in which pdon shows a single chelating coordination. Electrochemical properties of the title compounds have been investigated.