Bonding Trends in Tetravalent Th–Pu Monosalen Complexes |
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Authors: | Thomas Radoske Dr Juliane März Dr Michael Patzschke Dr Peter Kaden Dr Olaf Walter Dr Moritz Schmidt Prof Dr Thorsten Stumpf |
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Institution: | 1. Institute of Resource Ecology, Helmholtz-Zentrum Dresden-Rossendorf (HZDR), Bautzner Landstrasse 400, 01328 Dresden, Germany;2. European Commission, DG JRC, G.I.5, PO Box 2340, 76125 Karlsruhe, Germany |
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Abstract: | The synthesis of three complex series of the form AnCl2(salen)(Pyx)2] (H2salen=N,N′-bis(salicylidene)ethylenediamine; Pyx=pyridine, 4-methylpyridine, 3,5-dimethylpyridine) with tetravalent early actinides (An=Th, U, Np, Pu) is reported with the goal to elucidate the affinity of these heavy elements for small neutral N-donor molecules. Structure determination by single-crystal XRD and characterization of bulk powders with infrared spectroscopy reveals isostructurality within each respective series and the same complex conformation in all reported structures. Although the trend of interatomic distances for An−Cl and An−N (imine nitrogen of salen or pyridyl nitrogen of Pyx) was found to reflect an ionic behavior, the trend of the An−O distances can only be described with additional covalent interactions for all elements heavier than thorium. All experimental results are supported by quantum chemical calculations, which confirm the mostly ionic character in the An−N and An−Cl bonds, as well as the highest degree of covalency of the An−O bonds. Structurally, the calculations indicate just minor electronic or steric effects of the additional Pyx substituents on the complex properties. |
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Keywords: | bonding analysis covalency pyridine salen tetravalent actinide |
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