Novel Thorium Arsenic Multiple Bonds

A recent Nature Communication paper reports thorium complexes with Th-As multiple bonds, stabilized by bulky triamidoamine ligands. The bonding interactions in the novel thorium arsinidiides (ThAs(H)K and ThAs(H)Th) and arsenido (ThAsTh) are studied with relativistic DFT and display polarized-covalent multiple bonds, originating from the involvement of the 5f, 6d and 7s orbitals.

HOMOs of ThAsTh complex

Highest occupied orbitals of dithorium arsinidiide [{Th(TrenTIPS)}2(μ-AsH)], the first complex with multiple thorium-arsenic bonds stable under ambient conditions.


This study further advances the fundamental understanding of multiple bonding in actinide complexes, which can ultimately help to design ligands for nuclear waste treatment. See also these recent papers and the previous highlight from the Liddle group on novel uranium complexes.

Thorium–phosphorus triamidoamine complexes containing Th–P single- and multiple-bond interactions, Nat. Comm. 7, 12884 (2016).
Isolation of Elusive HAsAsH in a Crystalline Diuranium(IV) Complex, Angew. Chem. Int. Ed. 54, 15250-15254 (2015).
Triamidoamine uranium(IV)–arsenic complexes containing one-, two- and threefold U–As bonding interactions, Nature Chem. 7, 582-590 (2015).
Synthesis and Characterization of an f‑Block Terminal Parent Imido [U=NH] Complex: A Masked Uranium(IV) Nitride, J. Am. Chem. Soc. 136, 5619-5622 (2014).
Triamidoamine-Uranium(IV)-Stabilized Terminal Parent Phosphide and Phosphinidene Complexes, Angew. Chem. Int. Ed. 53, 4484-4488 (2014).

Reference: E. P. Wildman, G. Balázs, A. J. Wooles, M. Scheer, and S. T. Liddle, Triamidoamine thorium-arsenic complexes with parent arsenide, arsinidiide and arsenido structural motifs, Nature Comm. 8, 14769 (2017).

Key concepts