科研之友
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摘要
Understanding of reaction and structural property of diuranium(III) complexes of a single ligand is essential to advancing their experimental synthesis and exploring promising applications in small molecule activation chemistry. In this work, we theoretically examined a series of diuranium(III) complexes building on the reaction of [UI3(THF)(4)] and octadentate polypyrrolic ligands (H4L1 and H4L2). At the relativistic density functional theory level, 11.2 kcal/mol energy is required to form the Pacman-like [(UI)(2)(mu(2)-I)(L-1)](-) (1) in THF solution, while only 0.5 kcal/mol for its non-classic Pacman isomer 1n. These agree with their analogues that have been experimentally proposed. A variety of chemical modification has been made for 1. The addition of one THF solvent or one iodine ion raises reaction energy by 6.8 similar to 14.5 kcal/mol, while two or more are significantly endoergic. Smaller energies of 1.4 and 7.4 kcal/mol are required when varying bridged atom (from the iodine of 1 into the THF of 2 [(UI)(2)(mu(2)-THF)(L-1)]) and lengthening ligand linker size (from ortho-phenylene of H4L1 of 1 into anthracene of H4L2 of 3 [(UI)(2)(mu(2)-I)(L-2)](-)), respectively. Eleven diuranium(III) complexes were optimized to be energetically stable. The U-U distances of 4.13 and 4.08 angstrom were calculated for 1 and 2, respectively, compared with the long one of 5.90 angstrom for 3.
