The Renaissance of Non‐Aqueous Uranium Chemistry

Abstract

Prior to the year 2000, non-aqueous uranium chemistry mainly involved metallocene and classical alkyl, amide, or alkoxide compounds as well as established carbene, imido, and oxo derivatives. Since then, there has been a resurgence of the area, and dramatic developments of supporting ligands and multiply bonded ligand types, small-molecule activation, and magnetism have been reported. This Review 1) introduces the reader to some of the specialist theories of the area, 2) covers all-important starting materials, 3) surveys contemporary ligand classes installed at uranium, including alkyl, aryl, arene, carbene, amide, imide, nitride, alkoxide, aryloxide, and oxo compounds, 4) describes advances in the area of single-molecule magnetism, and 5) summarizes the coordination and activation of small molecules, including carbon monoxide, carbon dioxide, nitric oxide, dinitrogen, white phosphorus, and alkanes.

Organometallic neptunium(III) complexes

“…The shorter of the two Np-O bond lengths, 2.296(8) Å, is longer than the Np IV -OPh bond of 2.137(7) Å in 175 Cp 3 Np(OPh) [27] . This O-C bond cleavage is common for reduced electropositive metal complexes, and supports the assignment of a reactive Np II centre in 3a.…”

“…The selectivity of the best available An III extractants is attributed to subtly higher bonding covalency, but is not well understood and theory cannot yet make predictions.Unlike the organometallic chemistry of uranium, which has focused strongly on U III and seen spectacular advances [2][3][4] , that of the transuranics has remained dormant and, in the case of neptunium, is limited mainly to Np IV . The only known organometallic compounds of neptunium, the first transuranic element, are a …”

“…Analyses now standard in organometallic chemistry such as single crystal X-ray structures were determined for only a few Np IV complexes, and 1 H NMR spectroscopic data reported in 50 just a couple of cases. While exploratory reductions to the Np III oxidation state afforded powders presumed to be solvated Np III Cp 3 and K[Np(COT) 2 ] respectively, only scant spectroscopic data, and no structural data exist for any organometallic Np III complex 10,11 . The severe radiotoxicity of Np, the accessibility of its radionuclides, and the requirements to work with small sample sizes compound the traditional difficulties associated with handling air-sensitive, highly paramagnetic organometallic early 55 actinide complexes.…”

Thorium(IV) alkyl synthesis from a thorium(III) cyclopentadienyl complex and an N-heterocyclic olefin

“…Compared to extensive investigations spanning decades regarding transition metal carbene complexes, related studies in the actinide series remain relatively rare [1][2][3][4][5][6]. After Gilje's seminal report of the tris(cyclopentadienyl) uranium-carbene complex, [U(η 5 -Cp) 3 (CHPMe 2 Ph)] (I, Figure 1) [7], and some related reactivity studies [8][9][10][11][12][13][14][15][16], the area fell into abeyance for over 25 years.…”

Molecular Pnictogen Activation by Rare Earth and Actinide Complexes

“…In terms of rare earth N2 activation; an account of work from Evans and co-workers to 2004 has been reported [49], and Gardiner more recently reviewed the chemistry of the lanthanides with dinitrogen and reduced derivatives [50]. The area of actinide N2 activation has been discussed in the context of small molecule activation by trivalent uranium complexes [51,52].…”