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Synthesis of uranium(VI) terminal oxo complexes: Molecular geometry driven by the inverse trans -influence

Kosog B, la Pierre HS, Heinemann FW, Liddle ST, Meyer K (2012)

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Publication Type: Journal article, Original article

Publication year: 2012

Journal

Original Authors: Kosog B., La Pierre H.S., Heinemann F.W., Liddle S.T., Meyer K.

Publisher: American Chemical Society

Book Volume: 134

Pages Range: 5284-5289

Journal Issue: 11

DOI: 10.1021/ja211618v

Abstract

Oxidation of our previously reported uranium(V) oxo complexes, supported by the chelating ( ArO) tacn ligand system (R = tert-butyl (t-Bu), 1-t-Bu; R = 1-adamantyl (Ad), 1-Ad), yields terminal uranium(VI) oxo complexes [(( ArO) tacn)U(VI)(O)]SbF (R = t-Bu, 2-t-Bu; R = Ad, 2-Ad). These complexes differ in their molecular geometry in that 2-t-Bu possesses pseudo-C symmetry in solution and solid state as the terminal oxo ligand lies in the equatorial plane (as defined by the three aryloxide arms of the ligand) in order to accommodate the thermodynamic preference of high-valent uranium oxo complexes to have a δ- and π-donating ligand trans to the oxo (vis-à-vis the ubiquity of the linear UO moiety). The distortion of the ligand - which stands in contrast to all other complexes of uranium supported by the ( ArO) tacn ligand, including 2-Ad - is most clearly seen in the structures of 2-t-Bu, [(( ArO) tacn)U(VI)(O) ]SbF , and 3-t-Bu, [(( ArO) tacn)U(VI)(O) (OC(O) CF ) ]. The solid-state structure of 3-t-Bu reveals that the trans U-O bond length is shortened by 0.1 Å in comparison to the cis U-O bonds and the trans U-O-C angle is linearized (157.67° versus 147.85° and 130.03°). Remarkably, the minor modification of the ligand to have Ad groups at the ortho positions of the aryloxide arms is sufficient to stabilize a C -symmetric terminal uranium(VI) oxo complex (2-Ad) without a ligand trans to the oxo. These experimental results were reproduced in DFT calculations and allow the qualitative bracketing of the relative thermodynamic stabilization afforded by the inverse trans-influence as ∼6 kcal mol . © 2012 American Chemical Society.

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APA:

Kosog, B., la Pierre, H.S., Heinemann, F.W., Liddle, S.T., & Meyer, K. (2012). Synthesis of uranium(VI) terminal oxo complexes: Molecular geometry driven by the inverse trans -influence. Journal of the American Chemical Society, 134(11), 5284-5289. https://doi.org/10.1021/ja211618v

MLA:

Kosog, Boris, et al. "Synthesis of uranium(VI) terminal oxo complexes: Molecular geometry driven by the inverse trans -influence." Journal of the American Chemical Society 134.11 (2012): 5284-5289.

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