A new Wells–Dawson organic–inorganic hybrid polytungstate containing dimeric silver coordination complexes: (Hpy)₂[Ag₂(phen)₄]₂(P₂W₁₈O₆₂)

An attempt to incorporate Ag⁺ ions and some organic-reducing ingredients (e.g. pyridine) simultaneously into a polyoxometalate is a challenging task due to the high-standard reduction potential of Ag⁺ ions. By using a second organic ligand to coordinate Ag⁺ first, we prepared a new polytungstate, (Hpy)₂[Ag₂(phen)₄]₂(P₂W₁₈O₆₂) (1) (py = pyridine (C₅NH₅), phen = 1,10-phenanthroline (C₁₂N₂H₈)), which contains discrete inorganic polyanions ([P₂W₁₈O₆₂]^6–), protonated pyridine molecules, and [Ag₂(phen)₄]²⁺ dimers. The isolated inorganic polyanions cluster close to the planes of (1 0 0) and are bound together by pyridine molecules via hydrogen bonds to form layers parallel to (1 0 0) at (0, y, z) and (0.5, y, z). The [Ag₂(phen)₄]²⁺ dimers are located between successive layers of (1 0 0) and represent an uncommon feature that the hexagonal benzene rings of phen molecules are directly overlapped face to face. Our work opens a new way for synthesis of other Wells–Dawson organic–inorganic hybrid polytungstates by controlling reactant addition order.