Chen Xiuting, Xiong Zhixin, Gong Yu
Department of Radiochemistry, Shanghai Institute of Applied Physics, Chinese Academy of Sciences, Shanghai 201800, China.
School of Nuclear Science and Technology, University of Chinese Academy of Sciences, Beijing 100049, China.
J Am Soc Mass Spectrom. 2021 Mar 3;32(3):700-706. doi: 10.1021/jasms.0c00420. Epub 2021 Feb 1.
Gas-phase tetrapositively charged M(HMNTA) (M = Zr, Hf, Th, and U) ions were generated via electrospray ionization of the M(ClO) and ,,',',″,″-hexamethylnitrilotriacetamide (HMNTA) mixtures in acetonitrile. In these complexes, the Zr, Hf, Th, and U metal centers are coordinated by two neutral HMNTA ligands forming antitriangular prism geometry on the basis of DFT calculations. Bonding analysis reveals that the M center is stabilized by six carbonyl oxygen atoms, while the interactions between M and two central amine nitrogen atoms are negligible. This is further confirmed by the calculation results of two tetrapositive model complexes without either central amine nitrogen or carbonyl oxygen atoms, indicating the central nitrogen atom of HMNTA is not necessary in forming tetrapositive metal complexes that can be stabilized in gas phase. Collision-induced dissociation of Zr(HMNTA), Hf(HMNTA), and Th(HMNTA) shows the formation of similar charge reducing products with the oxidation state of metal retaining IV whereas ions with other oxidation states were observed for the fragmentation products of U(HMNTA).
通过在乙腈中对M(ClO)和N,N',N'',N'''-六甲基次氮基三乙酰胺（HMNTA）混合物进行电喷雾电离，生成了气相四价带电的M(HMNTA)（M = Zr、Hf、Th和U）离子。在这些配合物中，基于密度泛函理论计算，Zr、Hf、Th和U金属中心由两个中性HMNTA配体配位，形成反三棱柱几何结构。键合分析表明，M中心由六个羰基氧原子稳定，而M与两个中心胺氮原子之间的相互作用可忽略不计。这通过两个没有中心胺氮或羰基氧原子的四价模型配合物的计算结果得到进一步证实，表明HMNTA的中心氮原子对于形成可在气相中稳定的四价金属配合物并非必要。Zr(HMNTA)、Hf(HMNTA)和Th(HMNTA)的碰撞诱导解离显示形成了类似的电荷减少产物，金属的氧化态保持为IV，而对于U(HMNTA)的碎片产物观察到了具有其他氧化态的离子。
