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The reaction of 1 equiv of 1-azidoadamantane with [U
(NR
)
] (R = SiMe
) in Et
O results in the formation of [U
(NR
)
(NAd)] (
, Ad = 1-adamantyl) in good yields. The electronic structure of
, as well as those of the related U(V) complexes, [U
(NR
)
(NSiMe
)] (
) and [U
(NR
)
(O)] (
), were analyzed with EPR spectroscopy, SQUID magnetometry, NIR-visible spectroscopy, and crystal field modeling. This analysis revealed that, within this series of complexes, the steric bulk of the E
(E═O, NR) ligand is the most important factor in determining the electronic structure. In particular, the increasing steric bulk of this ligand, on moving from O
to [NAd]
, results in increasing U═E distances and E-U-N
angles. These changes have two principal effects on the resulting electronic structure: (1) the increasing U═E distances decreases the energy of the f
orbital, which is primarily σ* with respect to the U═E bond, and (2) the increasing E-U-N
angles increases the energy of f
, due to increasing antibonding interactions with the amide ligands. As a result of the latter change, the electronic ground state for complexes
and
is primarily f
in character, whereas the ground state for complex
is primarily f
.