Highly Diverse Bonding between Two U3+ Ions When Ligated by a Flexible Polypyrrolic Macrocycle

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• 作者：Dong-Mei Su ; Xiu-Jun Zheng ; Georg Schreckenbach ; Qing-Jiang Pan
• 刊名：Organometallics
• 出版年：2015
• 出版时间：November 9, 2015
• 年：2015
• 卷：34
• 期：21
• 页码：5225-5232
• 全文大小：445K
• ISSN：1520-6041

文摘

A Schiff-base polypyrrolic ligand (H₄L) can accommodate two U³⁺ ions and form a Pacman-like complex [U₂(L)]²⁺ according to relativistic density functional theory. Sixteen species, featuring four structural models in four electronic states, are energetically stable. Ligand flexibility, lack of axial restriction, and suitable U鈥揘 interactions allow the two U³⁺ ions to stretch freely over a wide range, in contrast to U₂@C_n (n = 60, 74, 80) studied previously. Diverse U³⁺鈥揢³⁺ interactions are found. The quintet state of the Out鈥揑n model, which is calculated to be the global ground state both including and excluding the spin鈥搊rbit coupling energy, likely shows a weak single U₂ bond. In both vertical and tilt In鈥揑n species, a triple bond is found. It is composed of two two-electron鈥搕wo-center bonds and two one-electron鈥搕wo-center bonds; moreover, the tilt conformer is almost isoenergetic with Out鈥揑n. The Out鈥揙ut species shows no U路路路U bonding. Comparison with explicitly THF-solvated diuranium complexes is also addressed.