New publication

Axially symmetric U-O-Ln and U-O-U containing molecules from the control of uranyl reduction with simple f-block halides

P. L. Arnold, B. E. Cowie, M. Suvova, M. Zegke, N. Magnani, E. Colineau, J-C Griveau, R. Caciuffo, J. B. Love

Angew. Chem. Int. Ed., 2017, DOI: 10.1002/anie.201705197

Cowie ANIE2017

Stuck on U: Simple, tunable reactions between Ln(II) iodides and uranyl salts in pyridine or acetonitrile generate axially symmetric, one-or two-electron reduced, discrete or infinite, oxo-coupled 4f/5f systems, allowing fundamental electronic or magnetic properties to be tuned and studied.

 

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3MT Winner!

Congratulations to Euan Doidge for winning the University-wide Three Minute Thesis competition with his presentation “WEEE are golden: metal recovery by solvent extraction”. He will now represent the University at National level! Euan also came away with the ‘People’s Choice’ prize.Euan Doidge 3MT

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Prize winning talks

Congratulations to Euan Doidge (Materials Chemistry) and Innis Carson (Physical Chemistry) for winning 1st prizes for their presentations at the School’s Joseph Black Conference. Well done!

Euan and Innis JBconference 2017

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New publication

Reduction of carbon dioxide and organic carbonyls by hydrosilanes catalysed by the perrhenate anion

Danny S. Morris, Catherine Weetman, Julian T. C. Wennmacher, Mirza Cokoja, Markus Drees, Fritz E. Kühn, and Jason B. Love, Catal. Sci. Technol., 2017

ToC CatSciTechnol

The simple perrhenate salt [N(hexyl)4][(ReO4)] acts as a catalyst for the reduction of organic carbonyls and carbon dioxide by primary and secondary hydrosilanes. In the case of CO2, this results in the formation of methanol equivalents via silylformate and silylacetal intermediates. Furthermore, the addition of alkylamines to the reaction mixture favours catalytic amine N-methylation over methanol production under certain conditions. DFT analysis of the mechanism of CO2 reduction shows that the perrhenate anion activates the silylhydride forming a hypervalent silicate transition state such that the CO2 can directly cleave a Si-H bond.

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New publication

“Triggering redox activity in a thiophene compound: radical stabilization and coordination chemistry”

M. Curcio, J. R. Pankhurst, S. Sproules, D. Mignard, J. B. Love, Angew. Chem. Int. Ed.2017, DOI: 10.1002/anie.201703576R1

thiophene

Abstract: The synthesis, metalation, and redox properties of an acyclic bis(iminothienyl)methene L are presented. This π-conjugated anion displays pronounced redox activity, undergoing facile one-electron oxidation to the acyclic, metal-free, neutral radical L on reaction with FeBr2. In contrast, reaction of L with CuI forms the unique, neutral Cu2I2(L) complex of a ligand-centered radical, whereas reaction with the stronger oxidant AgBF4 forms the metal-free radical dication L2+.

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New publication

Multi-electron reduction of sulfur and carbon disulfide using binuclear uranium(III) borohydride complexes

Polly L. Arnold,* Charlotte J. Stevens, Nicola L. Bell, Rianne M. Lord, Jonathan M. Goldberg, Gary S. Nichol and Jason B. Love* Chem. Sci. 2017, DOI: 10.1039/c7sc00382j

chemsci2017

The first use of a dinuclear UIII/UIII complex in the activation of small molecules is reported. The octadentate Schiff-base pyrrole, anthracene-hinged ‘Pacman’ ligand LA combines two strongly reducing UIII centres and three borohydride ligands in [M(THF)4][{U(BH4)}2(µ-BH4)(LA)(THF)2] 1-M, (M = Li, Na, K). The two borohydride ligands bound to uranium outside the macrocyclic cleft are readily substituted by aryloxide ligands, resulting in a single, weakly-bound, encapsulated endo potassium borohydride bridging the two UIII centres in [{U(OAr)}2(m-MBH4)(LA)(THF)2] 2-M (OAr = OC6H2tBu3-2,4,6, M = Na, K). X-ray crystallographic analysis shows that, for 2-K, in addition to the endo-BH4 ligand the potassium counter-cation is also incorporated into the cleft through η5-interactions with the pyrrolides instead of extraneous donor solvent. As such, 2-K has a significantly higher solubility in non-polar solvents and a wider U-U separation compared to the ‘ate’ complex 1. The cooperative reducing capability of the two UIII centres now enforced by the large and relatively flexible macrocycle is compared for the two complexes, recognising that the borohydrides can provide additional reducing capability, and that the aryloxide-capped 2-K is constrained to reactions within the cleft. The reaction between 1-Na and S8 affords an insoluble, presumably polymeric paramagnetic complex with bridging uranium sulfides, while that with CS2 results in oxidation of each UIII to the notably high UV oxidation state, forming the unusual trithiocarbonate (CS3)2- as a ligand in [{U(CS3)}2(m-k1:k1:h2-CS3)(LA)] (4). The reaction between 2-K and S8 results in quantitative substitution of the endo-KBH4 by a bridging persulfido (S2)2- group and oxidation of each UIII to UIV, yielding [{U(OAr)}2(μ-h2:h2-S2)(LA)] (5). The reaction of 2-K with CS2 affords a thermally unstable adduct which is tentatively assigned as containing a carbon disulfido (CS2)2- ligand bridging the two U centres (6a), but only the mono-bridged sulfido (S)2- complex [{U(OAr)}2(μ-S)(LA)] (6) is isolated. The persulfido complex (5) can also be synthesised from the mono-bridged sulfido complex (6) by the addition of another equivalent of sulfur.

 

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Welcome to Daniel

Daniel Henschel from the Technical University of Munich has joined the group for the next 6 months to carry out his Master’s thesis project on sulfur analogues of dipyrrin complexes for small molecule activation.

p1000198

 

 

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