Crystal structures of three copper(II)–2,2′-bi­pyridine (bpy) compounds, [Cu(bpy)2(H2O)][SiF6]·4H2O, [Cu(bpy)2(TaF6)2] and [Cu(bpy)3][TaF6]2 and a related coordination polymer, [Cu(bpy)(H2O)2SnF6]n

We report the hydro­thermal syntheses and crystal structures of aqua­bis­(2,2′-bi­pyridine-κ2N,N′)copper(II) hexa­fluorido­silicate tetra­hydrate, [Cu(bpy)2(H2O)][SiF6]·4H2O (bpy is 2,2′-bi­pyridine, C10H8N2), (I), bis­(2,2′-bi­pyridine-3κ2N,N′)-di-μ-fluorido-1:3κ2F:F;2:3κ2F:F-deca­fluorido-1κ5F,2κ5F-ditantalum(V)copper(II), [Cu(bpy)2(TaF6)2], (II), tris­(2,2′-bi­pyridine-κ2N,N′)copper(II) bis[hexa­fluorido­tantalate(V)], [Cu(bpy)3][TaF6]2, (III), and catena-poly[di­aqua­(2,2′-bi­pyridine-κ2N,N′)copper(II)]-μ-fluorido-tetra­fluorido­tin-μ-fluorido], [Cu(bpy)(H2O)2SnF6]n, (IV). Compounds (I), (II) and (III) contain locally chiral copper coordination complexes with C2, D2, and D3 symmetry, respectively. The extended structures of (I) and (IV) are consolidated by O—H⋯F and O—H⋯O hydrogen bonds. The structure of (III) was found to be a merohedral (racemic) twin.