Three isomorphous Ln complexes: {[Ln₂(bt)₆(bno)(H₂O)₄]·bno}_n (bt is but-2-enoate and bno is 4,4′-bipyridyl N,N′-dioxide), with Ln = Nd, Er and Y

The polymeric title compounds, namely catena-poly[[[di-μ-but-2-enoato-κ³O:O,O′;κ³O,O′:O′-bis­[diaqua­dibut-2-enoato-κO;κ²O,O′-neodymium(III)]]-μ-4,4′-bipyridyl N,N′-dioxide-κ²O:O′] 4,4′-bipyridyl N,N′-dioxide solvate] and the erbium(III) and yttrium(III) analogues, {[Ln₂(C₄H₅O₂)₆(C₁₀H₈N₂O₂)(H₂O)₄]·C₁₀H₈N₂O₂}_n (Ln = Nd, Er and Y), form from [Ln₂(bt)₆(H₂O)₄] dimers (bt is but-2-enoate) bridged by 4,4′-bipyridyl dioxide (bno) spacers into sets of parallel chains; these linear arrays are inter­connected by aqua-mediated hydrogen bonds into broad two-dimensional structures, which in turn inter­act with each other though the hydrogen-bonded bridged bno solvent units. Both independent bno units in the structures are bisected by symmetry centres.