Synthesis, Characterization, and Density Functional Theory Analysis of Uranium and Thorium Complexes Containing Nitrogen-Rich 5-Methyltetrazolate Ligands.
Two nitrogen-rich, isostructural complexes of uranium and thorium, (C5Me5)2U[η(2)-(N,N')-tetrazolate]2 (7) and (C5Me5)2Th[η(2)-(N,N')-tetrazolate]2 (8), containing 5-methyltetrazolate, have been synthesized and structurally characterized by single-crystal X-ray diffraction, electrochemical methods, UV-visible-near-IR spectroscopy, and variable-temperature (1)H NMR spectroscopy. Density functional theory (DFT) calculations yield favorable free energies of formation (approximately -375 kJ/mol) and optimized structures in good agreement with the experimental crystal structures. Additionally, calculated NMR chemical shifts of 7 and 8 are in good agreement with the variable-temperature (1)H NMR experiments. Time-dependent DFT calculations of both complexes yield UV-visible spectroscopic features that are consistent with experiment and provide assignments of the corresponding electronic transitions. The electronic transitions in the UV-visible spectroscopic region are attributed to C5Me5 ligand-to-metal charge transfer. The low-lying molecular orbitals of the tetrazolate ligands (∼2 eV below the HOMO) do not contribute appreciably to experimentally observed electronic transitions. The combined experimental and theoretical analysis of these new nitrogen-rich uranium and thorium complexes indicates the tetrazolate ligand behaves primarily as a σ-donor.
Los Alamos National Laboratory , Los Alamos, New Mexico 87545, United States.
Kevin P
KP
Browne
Los Alamos National Laboratory , Los Alamos, New Mexico 87545, United States.
Katie A
KA
Maerzke
Los Alamos National Laboratory , Los Alamos, New Mexico 87545, United States.
Nicholas E
NE
Travia
Los Alamos National Laboratory , Los Alamos, New Mexico 87545, United States.
David E
DE
Morris
Los Alamos National Laboratory , Los Alamos, New Mexico 87545, United States.
Brian L
BL
Scott
Los Alamos National Laboratory , Los Alamos, New Mexico 87545, United States.
Neil J
NJ
Henson
Los Alamos National Laboratory , Los Alamos, New Mexico 87545, United States.
Ping
P
Yang
Los Alamos National Laboratory , Los Alamos, New Mexico 87545, United States.
Jaqueline L
JL
Kiplinger
Los Alamos National Laboratory , Los Alamos, New Mexico 87545, United States.
Jacqueline M
JM
Veauthier