Th(IV) complexes with cis-ethylenebis(diphenylphosphine oxide): X-ray structures and NMR solution studies

Abstract

The complexation of Th(NO3)4 with the rigid diphosphoryl ligand cis-ethylenebis(diphenylphosphine oxide) has been investigated using X-ray crystallography, IR, NMR and CHN analysis. Three crystal polymorphs were grown out of methanolic solution where the 1:3 Th(IV)–ligand complex is ten-coordinate, and the metal is bound by three bidentate ligands and two nitrato groups. An additional metal–ligand complex with similar geometry was also grown from the non-coordinating solvent CHCl3. Analysis of CD3OD and CDCl3 solutions of this complex using 1H and 31P NMR reveals that ligand exchange rates are fast on the NMR time scale in methanol-d4, and slow on the NMR time scale in chloroform-d. Further, three additional crystal structures are reported describing the 1:1 and 1:2 Th(IV)–ligand complex, the 1:3 Th(IV)–ligand complex with an extra aqua ligand, and a serendipitous 1:3 Th(IV)–ligand structure where one ligand bears an epoxide.