pH-Dependent Syntheses and Crystal Structures of a Series of Organic−Inorganic Hybrids Constructed from Keggin or Wells−Dawson Polyoxometalates and Silver Coordination Compounds

A series of silver complexes of polyoxometalates (POMs), formulated as, [Ag2(4,4′-bpy)2(4,4′-Hbpy)(H2O)][PW12O40] (4,4′-bpy = 4,4′-bipyridine, 1), [Ag4(4,4′-bpy)4][4,4′-H2bpy][P2W18O62]·4H2O (2), [Ag4(4,4′-bpy)4][H2P2W18O62]·7H2O (3), and Na8[Ag3(4,4′-bpy)3][PW10Ag2O39]·6H2O (4), have been hydrothermally synthesized in situ at different pH. Complex 1, based on saturated Keggin POM building blocks and silver coordination compounds, exhibits an interesting 3-fold interpenetration of diamondlike network in the POM chemistry. Different from complex 1, complexes 2−3 consist of Wells−Dawson polyoxoanions and silver coordination compounds. Complex 2 represents the highest coordination number of Wells−Dawson polyoxoanions, which helps to form a high-dimensional framework with (4·64·8)4(44·616·88) topology. Thee-dimensional (3D) Wells−Dawson phosphotungstate 3 reveals another new topology (4·64·7)(4·64·8)2(43·68·72·82). Complex 4 forms a 3D framework constructed from divacant Keggin polyoxoanions and silver coordination compounds. Their structural differences indicate that the pH value of the reaction system plays a key role on the structures and topologies of these complexes, and the whole self-assembly process is pH-dependent.