Complexes of a hexadentate podand ligand with actinides; The syntheses and crystal structures of [Th(Tp Py)(NO 3) 3] · (dmf) · (Et 2O) 0.5 and trans-[UO 2(Tp Py)(OEt)] Tp Py = tris[3-(2′-pyridyl)pyrazol-1-yl]hydroborate

Abstract

The syntheses and crystal structures of [Th(Tp Py)(NO 3) 3] ( 1) and trans-[UO 2(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 2O) 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.