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Synthesis and Characterization of a Uranium(II) Monoarene Complex Supported by δ Backbonding
Author(s) -
La Pierre Henry S.,
Scheurer Andreas,
Heinemann Frank W.,
Hieringer Wolfgang,
Meyer Karsten
Publication year - 2014
Publication title -
angewandte chemie
Language(s) - English
Resource type - Journals
eISSN - 1521-3757
pISSN - 0044-8249
DOI - 10.1002/ange.201402050
Subject(s) - chemistry , uranium , crystallography , electron paramagnetic resonance , electronic structure , thorium , metal , magnetism , absorption spectroscopy , spectroscopy , computational chemistry , nuclear magnetic resonance , materials science , organic chemistry , physics , quantum mechanics , metallurgy
The low‐temperature (<−35 °C) reduction of the trivalent uranium monoarene complex [{( Ad,Me ArO) 3 mes}U] ( 1 ), with potassium spheres in the presence of a slight excess of 2.2.2‐cryptand, affords the quantitative conversion of 1 into the uranium(II) monoarene complex [K(2.2.2‐crypt)][(( Ad,Me ArO) 3 mes)U] ( 1‐K ). The molecular and electronic structure of 1‐K was established experimentally by single‐crystal X‐ray diffraction, variable‐temperature 1 H NMR and X‐band EPR spectroscopy, solution‐state and solid‐state magnetism studies, and optical absorption spectroscopy. The electronic structure of the complex was further investigated by DFT calculations. The complete body of evidence confirms that 1‐K is a uranium(II) monoarene complex with a 5f 4 electronic configuration supported by δ backbonding and that the nearly reversible, room‐temperature reduction observed for 1 at −2.495 V vs. Fc/Fc + is principally metal‐centered.