Reactions of ThX4 (X=F, Cl, Br, I) with Liquid Ammonia‐Crystal Structures and a Theoretical Study of Ammine Thorium(IV) Halide Ammoniates

H Lars Deubner,Florian Kraus,Tim Graubner,Florian Weigend,Antti J Karttunen

doi:10.1002/ejic.202100383

H Lars Deubner, Florian Kraus + Show 3 more

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https://doi.org/10.1002/ejic.202100383

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Abstract

AbstractReactions of thorium tetrahalides ThX4 (X=Cl, Br, I) with liquid ammonia at room temperature lead to the formation of decaammine thorium(IV) halide ammoniates. Their different compositions [Th(NH3)10]X4 ⋅ nNH3 were established by single crystal X‐ray diffraction. While for the chloride the formation of a tetraammoniate is observed, the reaction of the bromide leads to an octaammoniate, whereas the iodide results in approximately a nonaammoniate. Additionally, the formation of the dinuclear Th complex compound [Th2Cl2(NH3)14(μ‐O)]Cl4 ⋅ 3NH3 was observed when moisture was present within NH3. As expected, the Th and the previously reported U compounds [An(NH3)10]Br4 ⋅ 8NH3 (Pbca, An=Th, U), [An(NH3)10]I4 ⋅ 9NH3 (P4/n), and [An2Cl2(NH3)14(μ‐O)]Cl4 ⋅ 3NH3 (P ) are isotypic, respectively. Surprisingly, ThCl4 formed the decaammine complex [Th(NH3)10]Cl4 ⋅ 4NH3 (P121/n1), while UCl4 formed the octaammine chlorido complex [UCl(NH3)8]Cl3 ⋅ 3NH3 (Pnma) in ammonia. Quantum‐chemical gas‐phase calculations were carried out to study the molecular structures and the energetics of the complex cations. In addition, the localized molecular orbitals (LMO) and Intrinsic Bonding Orbitals (IBO) were analyzed. However, the calculations could not explain the preferred formation of the [Th(NH3)10]4+ complex over the hypothetical cation [ThCl(NH3)8]3+.

Highlights

We present crystal structures of some ammoniates of the thorium tetrahalides obtained from the reaction with liquid ammonia and compare them to those obtained for the respective reactions of the uranium tetrahalides
An overview of the reaction products of uranium[10] and thorium halides with liquid ammonia under different temperatures
To get an idea of the bonding situation and to see if different orbitals contribute to the AnÀCl bond in the [AnCl (NH3)8]3+ complexes, we studied the localized molecular orbitals (LMOs) for the respective cations

Summary

Introduction

The above-mentioned compounds are typically only stable up to a certain temperature under a certain ammonia equilibrium pressure and with rising the temperature the contained ammonia is typically given off step-wise and products of lower NH3 content are obtained and may be even isolated and characterized. At higher temperatures and/or ammonia pressures, ammonolysis reactions generally become faster, equilibria are shifted, and different products, such as amides, imides, or nitrides, may be obtained. We present crystal structures of some ammoniates of the thorium tetrahalides obtained from the reaction with liquid ammonia and compare them to those obtained for the respective reactions of the uranium tetrahalides. An overview of the reaction products of uranium[10] and thorium halides with liquid ammonia under different temperatures. The asterisk indicates that the used NaNH2 contained some NaOH

Results and Discussion

Conclusion

Conflict of Interest