Lanthanide Diruthenium(II,III) Compounds Showing Layered and PtS-Type Open Framework Structures

Two types of lanthanide diruthenium phosphonate compounds, based on the mixed-valent metal−metal bonded paddlewheel core of Ru₂(hedp)₂^3- [hedp = 1-hydroxyethylidenediphosphonate, CH₃C(OH)(PO₃)₂], have been prepared with the formulas Ln(H₂O)₄[Ru₂(hedp)₂(H₂O)₂]·5.5H₂O (1·Ln, Ln = La, Ce) and Ln(H₂O)₄[Ru₂(hedp)₂(H₂O)₂]·8H₂O (2·Ln, Ln = La, Ce, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Ho, Er). In both types, each Ru₂(hedp)₂(H₂O)₂^3- unit is linked by four Ln³⁺ions through four phosphonate oxygen (O_P) atoms and vice versa. The geometries of the {LnO_P4} group, however, are different in the two cases. In 1·Ln, the geometry of {LnO_P4} is closer to a distorted plane, and thus a square-grid layer structure is found. In 2·Ln, the geometry of {LnO_P4} is better described as a distorted tetrahedron; hence, a unique PtS-type open-framework structure is observed. The channels generated in structures 2·Ln are filled with water aggregates with extensive hydrogen-bond interactions. The magnetic and electrochemical properties are also investigated.