Two isomorphous crotonatolanthanide complexes: tetra-mu-but-2-enoato-bis[diaqua(but-2-enoato)Ln]-2,6-diaminopurine (1/2) (Ln = Dy and Ho).

The title isomorphous compounds, tetra-mu-but-2-enoato-bis[diaqua(but-2-enoato)dysprosium(III)]-2,6-diaminopurine (1/2), [Dy(2)(C(4)H(5)O(2))(6)(H(2)O)(4)].2C(5)H(6)N(6), and tetra-mu-but-2-enoato-bis[diaqua(but-2-enoato)holmium(III)]-2,6-diaminopurine (1/2), [Ho(2)(C(4)H(5)O(2))(6)(H(2)O)(4)].2C(5)H(6)N(6), consist of [Ln(crot)(3)(H(2)O)(2)](2) dimers (crot is crotonate or but-2-enoate; Ln is the lanthanide cation), built up around inversion centres and completed by 2,6-diaminopurine molecules. The lanthanide cation is coordinated by three chelating crotonate units and two water molecules. One of the chelating carboxylate groups acts also in a bridging mode sharing one O atom with both cations and the final result is a pair of DyO(9) tricapped prismatic polyhedra linked to each other through a central (Dy-O)(2) loop. A feature of the structures is the existence of a complex intermolecular interaction scheme involving two sets of tightly interlinked non-intersecting one-dimensional structures, one of them formed by the [Dy(crot)(3)(H(2)O)(2)](2) dimers (running along [100] and linked by O-H...O hydrogen bonds) and the second formed by 2,6-diaminopurine molecules (evolving along [010] linked by N-H...N hydrogen bonds).