University of Oulu

Tsoureas, N., Mansikkamäki, A., & Layfield, R. A. (2021). Synthesis, bonding properties and ether activation reactivity of cyclobutadienyl-ligated hybrid uranocenes. Chemical Science, 12(8), 2948–2954.

Synthesis, bonding properties and ether activation reactivity of cyclobutadienyl-ligated hybrid uranocenes

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Author: Tsoureas, Nikolaos1; Mansikkamäki, Akseli2; Layfield, Richard A.1
Organizations: 1Department of Chemistry, School of Life Sciences, University of Sussex, Brighton, BN1 9QJ, UK
2NMR Research Unit, University of Oulu, P. O. Box 8000, FI-90014, Finland
Format: article
Version: published version
Access: open
Online Access: PDF Full Text (PDF, 1.2 MB)
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Language: English
Published: Royal Society of Chemistry, 2021
Publish Date: 2021-03-09


A series of hybrid uranocenes consisting of uranium(IV) sandwiched between cyclobutadienyl (Cb) and cyclo-octatetraenyl (COT) ligands has been synthesized, structurally characterized and studied computationally. The dimetallic species [(η⁴-Cb′′′′)(η⁸-COT)U(μ:η²:η⁸-COT)U(THF)(η⁴-Cb′′′′)] (1) forms concomitantly with, and can be separated from, monometallic [(η⁴-Cb′′′′)U(THF)(η⁸-COT)] (2) (Cb′′′′ = 1,2,3,4-tetrakis(trimethylsilyl)cyclobutadienyl, COT = cyclo-octatetraenyl). In toluene solution at room temperature, 1 dissociates into 2 and the unsolvated uranocene [(η⁴-Cb′′′′)U(η⁸-COT)] (3). By applying a high vacuum, both 1 and 2 can be converted directly into 3. Using bulky silyl substituents on the COT ligand allowed isolation of base-free [(η⁴-Cb′′′′)U{η⁸-1,4-(iPr₃Si)₂C₈H₆}] (4), with compounds 3 and 4 being new members of the bis(annulene) family of actinocenes and the first to contain a cyclobutadienyl ligand. Computational studies show that the bonding in the hybrid uranocenes 3 and 4 has non-negligible covalency. New insight into actinocene bonding is provided by the complementary interactions of the different ligands with uranium, whereby the 6d orbitals interact most strongly with the cyclobutadienyl ligand and the 5f orbitals do so with the COT ligands. The redox-neutral activation of diethyl ether by [(η⁴-Cb′′′′)U(η⁸-C₈H₈)] is also described and represents a uranium-cyclobutadienyl cooperative process, potentially forming the basis of further small-molecule activation chemistry.

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Series: Chemical science
ISSN: 2041-6520
ISSN-E: 2041-6539
ISSN-L: 2041-6520
Volume: 12
Issue: 8
Pages: 2948 - 2954
DOI: 10.1039/D0SC05199C
Type of Publication: A1 Journal article – refereed
Field of Science: 114 Physical sciences
116 Chemical sciences
Funding: The authors thank the University of Sussex, the European Research Council (CoG RadMag, grant 646740), the EPSRC (EP/M022064/2), the Academy of Finland (grant 332294) and the University of Oulu (Kvantum Institute) for financial support. Computational resources were provided by the Center for Science in Finland and the Finnish Grid and Cloud Infrastructure project (urn:nbn:fi:research-infras-2016072533) for financial support.
Academy of Finland Grant Number: 332294
Detailed Information: 332294 (Academy of Finland Funding decision)
Dataset Reference: Electronic supplementary information (ESI) available: Synthesis, spectroscopic characterization, crystallography details, computational details. CCDC 2026517–2026520, 2049726 and 2049727. For ESI and crystallographic data in CIF or other electronic format see DOI: 10.1039/d0sc05199c.
Copyright information: © 2021 The Authors. This article is licensed under a Creative Commons Attribution 3.0 Unported Licence.