The linear actinyl ions, AnO22+ dominate the chemistry of light actinides in their hexavalent oxidation states, and have played a central role in discussions surrounding covalency between An=O and An-Cl bonds in the actinide series. With the discovery of the family of trans diimido U(NR)22+ containing compounds where R = But, Ph, 2,6-Pri2C6H3, 2,6-(CF3)2C6H3, we have the unique opportunity to assess the similarity in electronic structure between the isoelectronic AnO22+ and An(NR)22+ units. All of these complexes contain short U=N bonds in the range 1.85 � 1.88�. Hybrid DFT electronic structure calculations indicate a formal U-N triple bond similar to that observed for UO22+, with axial U=O and U=N bonds composed of 6ds, 6dp, 5fs, and 5fp interactions. The comparative equatorial U-Cl bonding was explored through Cl K-edge XAS spectra of the UO2Cl42- and U(NtBu)2Cl42- ions. Curve fits of the peaks reveal a very small % Cl 3p mixing whose interpretation will be discussed.

Evaluating orbital mixing in UO2Cl42- vs. U(NtBu)2Cl42- using Cl K-edge XAS and TDDFT

245th National Meeting (2013)

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