Complexes of a hexadentate podand ligand with actinides; The syntheses and crystal structures of [Th(Tp(Py))(NO3)(3)].(dmf).(Et(2)O)(0.5) and trans-[UO2(Tp(Py))(OEt)] {Tp(Py)=tris[3-(2'-pyridyl)-pyrazol-1-yl]hydroborate}

The syntheses and crystal structures of [Th(Tp(Py))(NO3)(3)] (1) and trans-[UO2(Tp(PY))(OEt)] (2) are described, where [Tp(Py)](-) is the potentially hexadentate podand ligand tris[3-(2'-pyridyl)-pyrazol-1-yl]hydroborate. In the crystal structure of (1) (dmf).(Et(2)O)(0.5) the Th(IV) centre lies within the encapsulating ligand cavity, and is 12-coordinate from the six N-donor atoms of [Tp(Py)](-) and three bidentate nitrate ligands. The molecule has crystallographically imposed threefold rotational symmetry, and the nitrate ions are interleaved between the bidentate arms of the podand. In contrast for (2), where it is sterically impossible for the trans-dioxouranium(IV) fragment to be wholly encapsulated, the coordination geometry is pentagonal bipyramidal. The pentagonal plane comprises two bidentate ligand arms and one ethoxide ligand; the third ligand arm is pendant.