Issue 31, 2018

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

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 dx2y2 orbital localised on vanadium.

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

Supplementary files

Article information

Article type
Paper
Submitted
31 Mar 2018
Accepted
02 Jun 2018
First published
06 Jun 2018
This article is Open Access
Creative Commons BY license

Dalton Trans., 2018,47, 10692-10701

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

J. R. Hickson, S. J. Horsewill, C. Bamforth, J. McGuire, C. Wilson, S. Sproules and J. H. Farnaby, Dalton Trans., 2018, 47, 10692 DOI: 10.1039/C8DT01262H

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