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.本研究报道了利用桥联α-烷基吡咯配体（bridged α-alkyl-pyrrolyl ligands）合成新型锕系配合物（actinide complexes）的工作。对该配体实施锂化反应后，与1当量锕系四氯化物（actinide tetrachloride，即铀或钍的四氯化物）进行反应，可获得收率优良的目标配合物。X射线衍射（X-ray diffraction）研究显示，吡咯基团（pyrrolyl moieties）呈现独特的η⁵:η⁵配位模式；当使用位阻较小的甲基化配体时，将锂化配体溶液快速加入金属前驱体（metal precursor）中，可得到双配体配合物（bis-ligated complex），经晶体结构分析（crystallographic analysis）确认其配位模式为η⁵:η¹配位。