The modular synthesis of rare earth-transition metal heterobimetallic complexes utilizing a redox-active ligand

Hickson, J. R., Horsewill, S., Bamforth, C., McGuire, J., Wilson, C. , Sproules, S. and Farnaby, J. H. (2018) The modular synthesis of rare earth-transition metal heterobimetallic complexes utilizing a redox-active ligand. Dalton Transactions, 47(31), pp. 10692-10701. (doi:10.1039/C8DT01262H) (PMID:29897068)

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Abstract

We report a robust and modular synthetic route to heterometallic rare earth-transition metal complexes. We have used the redox-active bridging ligand 1,10-phenathroline-5,6-dione (pd), which has selective N,N′ or O,O′ binding sites as the template for this synthetic route. The coordination complexes [Ln(hfac)3(N,N’-pd)] (Ln = Y [1], Gd [2]; hfac = hexafluoroacetylacetonate) were synthesised in high yield. These complexes have been fully characterised using a range of spectroscopic techniques. Solid state molecular structures of 1 and 2 have been determined by X-ray crystallography and display different pd binding modes in coordinating and non-coordinating solvents. Complexes 1 and 2 are unusually highly coloured in coordinating solvents, for example the vis-NIR spectrum of 1 in acetonitrile displays an electronic transition centred at 587 nm with an extinction coefficient consistent with significant charge transfer. The reaction between 1 and 2 and VCp2 or VCpt2 (Cpt = tetramethylcyclopentadienyl) resulted in the isolation of the heterobimetallic complexes, [Ln(hfac)3(N,N′-O,O′-pd)VCp2] (Ln = Y [3], Gd [4]) or [Ln(hfac)3(N,N′-O,O′-pd)VCpt2] (Ln = Y [5], Gd [6]). The solid state molecular structures of 3, 5 and 6 have been determined by X-ray crystallography. The spectroscopic data on 3–6 are consistent with oxidation of V(II) to V(IV) and reduction of pd to pd2− in the heterobimetallic complexes. The spin-Hamiltonian parameters from low temperature X-band EPR spectroscopy of 3 and 5 describe a 2A1 ground state, with a V(IV) centre. DFT calculations on 3 are in good agreement with experimental data and confirm the SOMO as the dx2−y2 orbital localised on vanadium.

Item Type:Articles
Additional Information:We acknowledge the EPSRC for PhD studentships to JRH (EP/L504786/1), Imperial College London (JRF to JHF) and the University of Glasgow for funding.
Status:Published
Refereed:Yes
Glasgow Author(s) Enlighten ID:Wilson, Dr Claire and Sproules, Dr Stephen and Farnaby, Dr Joy and McGuire, Jake and Hickson, Mr James Robert and Horsewill, Samuel
Authors: Hickson, J. R., Horsewill, S., Bamforth, C., McGuire, J., Wilson, C., Sproules, S., and Farnaby, J. H.
College/School:College of Science and Engineering > School of Chemistry
Journal Name:Dalton Transactions
Publisher:Royal Society of Chemistry
ISSN:1477-9226
ISSN (Online):1477-9234
Published Online:06 June 2018
Copyright Holders:Copyright © 2018 The Authors
First Published:First published in Dalton Transactions 47(31):10692-10701
Publisher Policy:Reproduced under a Creative Commons License

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Project CodeAward NoProject NamePrincipal InvestigatorFunder's NameFunder RefLead Dept
701101EPSRC 2015 DTPMary Beth KneafseyEngineering and Physical Sciences Research Council (EPSRC)EP/M508056/1R&I - RESEARCH STRATEGY & INNOVATION