Role of the meso substituent in defining the reduction of uranyl dipyrrin complexes

van Rees, K., Rajeshkumar, T., Maron, L., Sproules, S. and Love, J. B. (2022) Role of the meso substituent in defining the reduction of uranyl dipyrrin complexes. Inorganic Chemistry, 61(50), pp. 20424-20432. (doi: 10.1021/acs.inorgchem.2c03048) (PMID:36472325) (PMCID:PMC9768749)

Abstract

The uranyl complex UVIO2Cl(LMes) of the redox-active, acyclic dipyrrin–diimine anion LMes– [HLMes = 1,9-di-tert-butyl-imine-5-(mesityl)dipyrrin] is reported, and its redox property is explored and compared with that of the previously reported UVIO2Cl(LF) [HLF = 1,9-di-tert-butyl-imine-5-(pentafluorophenyl)dipyrrin] to understand the influence of the meso substituent. Cyclic voltammetry, electron paramagnetic resonance spectroscopy, and density functional theory studies show that the alteration from an electron-withdrawing meso substituent to an electron-donating meso substituent on the dipyrrin ligand significantly modifies the stability of the products formed after reduction. For UVIO2Cl(LMes), the formation of a diamond-shaped, oxo-bridged uranyl(V) dimer, [UVO2(LMes)]2 is seen, whereas in contrast, for UVIO2Cl(LF), only ligand reduction occurs. Computational modeling of these reactions shows that while ligand reduction followed by chloride dissociation occurs in both cases, ligand-to-metal electron transfer is favorable for UVIO2Cl(LMes) only, which subsequently facilitates uranyl(V) dimerization.

• Item Type: Articles
• Additional Information: The authors thank the University of Edinburgh, the EPSRC (UK), and the EPSRC CRITICAT Centre for Doctoral Training (PhD studentship to K.v.R.; grant EP/L016419/1) for financial support.
• Status: Published
• Refereed: Yes
• Glasgow Author(s) Enlighten ID: Sproules, Dr Stephen
• Authors: van Rees, K., Rajeshkumar, T., Maron, L., Sproules, S., and Love, J. B.
• College/School: College of Science and Engineering > School of Chemistry
• Journal Name: Inorganic Chemistry
• Publisher: American Chemical Society
• ISSN: 0020-1669
• ISSN (Online): 1520-510X
• Published Online: 06 December 2022
• Copyright Holders: Copyright © 2022 The Authors
• First Published: First published in Inorganic Chemistry 61(50): 20424-20432
• Publisher Policy: Reproduced under a Creative Commons License