Synthesis of Coordinatively Unsaturated Tetravalent Actinide Complexes with η5 Coordination of Pyrrole

The synthesis of new actinide complexes utilizing bridged α-alkyl-pyrrolyl ligands is presented. Lithiation of the ligands followed by treatment with 1 equiv of actinide tetrachloride (uranium or thorium) produces the desired complex in good yield. X-ray diffraction studies reveal unique η5:η5 coordination of the pyrrolyl moieties; when the nonsterically demanding methylated ligand is used, rapid addition of the lithiated ligand solution to the metal precursor forms a bis-ligated complex that reveals η5:η1 coordination as determined by crystallographic analysis.