Two isomorphous lanthanide crotonate complexes: di-μ-but-2-enoato-bis[diaquabis(but-2-enoato)dysprosium(III)] adenine monosolvate heptahydrate and the samarium(II) analogue

Abstract

The asymmetric unit of the title dimeric compounds, [Ln2(C4H5O2)6(H2O)4]·C5H5N5·7H2O, with Ln = Dy, (I), and Sm, (II), consists of an LnIIIcation, three crotonate (but-2-enoate) anions and two coordinated water molecules forming the neutral complex, cocrystallized with half of an external adenine molecule and 3.5 water molecules. The metal complex has crystallographic inversion symmetry. The LnO9coordination polyhedra are connected through the sharing of a single edge to form isolated dimeric units, with Ln...Ln separations of 4.1766 (12) Å for (I) and 4.2340 (12) Å for (II). The unbound adenine molecule and one of the solvent water molecules are disordered around an inversion centre into two overlapping, equally populated, units. The structure is sustained by a complex hydrogen-bonding scheme involving all possible O—H and N—H groups as donors, and crotonate and water O and adenine N atoms as acceptors. The system is compared with recently published related compounds.