Uranium triamidoamine chemistry

Abstract

Triamidoamine (Tren) complexes of the p- and d-block elements have been well-studied, and they display a diverse array of chemistry of academic, industrial and biological significance. Such in-depth investigations are not as widespread for Tren complexes of uranium, despite the general drive to better understand the chemical behaviour of uranium by virtue of its fundamental position within the nuclear sector. However, the chemistry of Tren-uranium complexes is characterised by the ability to stabilise otherwise reactive, multiply bonded main group donor atom ligands, construct uranium-metal bonds, promote small molecule activation, and support single molecule magnetism, all of which exploit the steric, electronic, thermodynamic and kinetic features of the Tren ligand system. This Feature Article presents a current account of the chemistry of Tren-uranium complexes.

Molecular and electronic structure of terminal and alkali metal-capped uranium(V) nitride complexes

“…49 The DCIP series 3M have {UN(M) 2 NU} cores, varying from planar for 3Li , 3Na and 3Cs to slightly bent- trans nitride geometries for 3K (Σ∠=350.8(3)°) and 3Rb (Σ∠=354.79 (16)°). The U≡N distances for 3Li – 3K (1.883 (4)–1.929(6) Å) are longer than for 3Rb and 3Cs (1.846(3) and 1.860(5) Å, respectively; though 3Cs and 3Li , 3Na just overlap statistically).…”

Trapping of a Highly Bent and Reduced Form of 2‐Phosphaethynolate in a Mixed‐Valence Diuranium–Triamidoamine Complex

“…In recent years,wehave been investigating the coordination chemistry of triamidoamine complexes of uranium and thorium, [10] and in particular complexes of the type [U-(Tren TIPS )X] n or [{U(Tren TIPS )} 2 (m-X)] n [Tren TIPS = N(CH 2 CH 2 NSiPr i 3 ) 3 ;X = formally charged ligand; n = 0o r À1].T he list of main group X-ligands is extensive and growing, and includes:-NH 2 , = NH, N, -PH 2 , = PH, m-P(H), m-P, m-cyclo-P 5 ,-AsH 2 , = AsH, m-As(H), m-As, AsK 2 , m-h 2 :h 2 -As 2 , m-h 2 :h 2 As 2 H 2 , m-h 3 :h 3 As 3 ,-E(SiMe 3 ) 2 (E = P, As,Sb), = O, m-S, m-h 2 :h 2 S 2 , m-Se,a nd m-Te. [11] It is clear, therefore,t hat uranium-Tren TIPS in mono-or bi-metallic formulations is highly effective at trapping otherwise elusive,r eactive main group fragments,and this can involve unusual, highly reduced formal charge states that are stabilised by U-X p-o rdbonding.…”

Isolation of Elusive HAsAsH in a Crystalline Diuranium(IV) Complex

“…[1, 20] The uranium–amide and uranium–amine bond lengths in 3 are typical of such distances. [21] The U–As distances of 3.1203(7) and 3.1273(7) Å in 3 are longer than the sum of the single bond covalent radii for uranium and arsenic (2.91 Å),[22] but are only slightly longer than the formal U–As covalent σ-bond in 2 (3.004(4) Å). [15] The As–As bond length in 3 of 2.4102(13) Å is consistent with a single rather than double bond,[23] the latter of which tends to be about 2.2 Å,[1] and rules out the presence of an (As 2 ) unit that when trapped between two transition metals exhibits As–As bond lengths of circa 2.2–2.3 Å (see 4 below).…”