The structural and spectroscopic characterisation of three actinyl complexes with coordinated and uncoordinated perrhenate: [UO2(ReO4)2(TPPO)3], [{(UO2)(TPPO)3}2(µ2-O2)][ReO4]2 and [NpO2(TPPO)4][ReO4]

Gordon H. John; Iain May; Mark J. Sarsfield; Helen M. Steele; David Collison; Madeleine Helliwell; James D. McKinney

doi:10.1039/B313045B

The structural and spectroscopic characterisation of three actinyl complexes with coordinated and uncoordinated perrhenate: [UO₂(ReO₄)₂(TPPO)₃], [{(UO₂)(TPPO)₃}₂(µ₂-O₂)][ReO₄]₂ and [NpO₂(TPPO)₄][ReO₄]†

Gordon H. John,^a Iain May,^a Mark J. Sarsfield,^a Helen M. Steele,^a David Collison,*^b Madeleine Helliwell^b and James D. McKinney^c

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* Corresponding authors

^a Centre for Radiochemistry Research, Department of Chemistry, The University of Manchester, Manchester, UK

^b Department of Chemistry, The University of Manchester, Manchester, UK
E-mail: David.Collison@man.ac.uk
Fax: +44 (0)161 2754598
Tel: +44 (0)161 2754660

^c BNFL, Sellafield, Seascale, Cumbria, UK

Abstract

The first structural characterization of an actinide complex with coordinated perrhenate is reported, [UO₂(ReO₄)₂(TPPO)₃] (1). In this {UO₂}²⁺ complex two [ReO₄]⁻ anions and three TPPO (triphenylphosphine oxide) P [double bond, length as m-dash] O donor ligands are coordinated in the equatorial plane in a cisoid arrangement. This bonding arrangement, and apparent strain observed in the equatorially bonded ligands, is attributed to the solid state packing in adjacent molecules in which hydrophobic TPPO ligands form an effective “shell” around a hydrophilic core of two UO₂(ReO₄)₂ moieties. Solid state vibrational spectroscopy (infrared and Raman), ³¹P CP MAS NMR and elemental analysis are also consistent with the formula of 1. Solution state vibrational spectroscopy and ³¹P NMR measurements in EtOH indicate the lability of the TPPO and [ReO₄]⁻ groups. The photolytic generation of peroxide in EtOH solutions of 1 leads to the formation of trace quantities of [{(UO₂)(TPPO)₃}₂(µ₂-O₂)][ReO₄]₂, 2, in which the coordinated [ReO₄]⁻ groups of 1 have been displaced by bridging O₂²⁻, derived from atmospheric O₂. Finally, attempts to synthesise a {NpO₂}⁺ analogue of 1 have resulted only in the formation of [NpO₂(TPPO)₄][ReO₄], 3, in which [ReO₄]⁻ acts solely as a counter anion. From these results it can be concluded that [ReO₄]⁻ will bond to {UO₂}²⁺, but will be readily displaced by a more strongly coordinating ligand (e.g. peroxide) and will not coordinate to an actinyl cation with a lower charge, {NpO₂}⁺, under the same reaction conditions.

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Article information

DOI: https://doi.org/10.1039/B313045B
Article type: Paper
Submitted: 16 Oct 2003
Accepted: 02 Dec 2003
First published: 30 Jan 2004

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Dalton Trans., 2004, 734-740

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The structural and spectroscopic characterisation of three actinyl complexes with coordinated and uncoordinated perrhenate: [UO₂(ReO₄)₂(TPPO)₃], [{(UO₂)(TPPO)₃}₂(µ₂-O₂)][ReO₄]₂ and [NpO₂(TPPO)₄][ReO₄]

G. H. John, I. May, M. J. Sarsfield, H. M. Steele, D. Collison, M. Helliwell and J. D. McKinney, Dalton Trans., 2004, 734 DOI: 10.1039/B313045B

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