Synthesis and Characterization of Two Uranyl‐Aryl “Ate” Complexes

Self Cite

The reaction of AnCl 4 (DME) n (An = Th, n = 2; U, n = 0) with 5 equiv of LiC 6 Cl 5 in Et 2 O resulted in the formation of homoleptic actinide-arylSimilarly, the reaction of AnCl 4 (DME) n (An = Th, n = 2; U, n = 0) with 3 equiv of LiC 6 Cl 5 in Et 2 O resulted in the formation of heteroleptic actinide-aryl). Density functional calculations show that the An−C ipso σbonds are considerably more covalent for the uranium complexes vs the thorium analogues, in line with past results. Additionally, good agreement between experiment and calculations is obtained for the 13 C ipso NMR chemical shifts in [Li][1] and [Li][3]. The calculations demonstrate a deshielding by ca. 29 ppm from spin−orbit coupling effects originating at Th, which is a direct consequence of 5f orbital participation in the Th−C bonds.

Section: Introductionsupporting

confidence: 54%

Homoleptic Perchlorophenyl “Ate” Complexes of Thorium(IV) and Uranium(IV)

Ordoñez

Autschbach

et al. 2021

Self Cite

“…As seen in Table , the calculated chemical shifts are only weakly dependent on the tested functionals; for brevity, we focus on the PBE/SO-PBE results. This functional has previously provided reliable chemical shifts in actinide complexes. , The calculated α-carbon shift for complex 2 is 174.9 ppm (expt. = 176.1 ppm) and includes a 32.2 ppm deshielding contribution due to SO effects.…”

Section: Resultsmentioning

confidence: 99%

“…Indeed, the use of NMR spectroscopy to study covalency is emerging as a valuable technique for probing the electronic structure of f-element–ligand bonds. A variety of nuclei have been employed for this purpose, including 77 Se, 125 Te, and 15 N. − This analysis has also been applied to a variety of organometallic actinide and lanthanide complexes, including those containing alkyl, aryl, and carbene ligands. − …”

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

Synthesis of Parent Acetylide and Dicarbide Complexes of Thorium and Uranium and an Examination of Their Electronic Structures

Kent

Pauly

et al. 2021

Self Cite

The reaction of [AnCl(NR2)3] (An = U or Th; R = SiMe3) with NaCCH and tetramethylethylenediamine (TMEDA) results in the formation of [An(CCH)(NR2)3] (1, An = U; 2, An = Th), which can be isolated in good yields after workup. Similarly, the reaction of 3 equiv of NaCCH and TMEDA with [AnCl(NR2)3] results in the formation of [Na(TMEDA)][An(CCH)2(NR2)3] (4, An = U; 5, An = Th), which can be isolated in fair yields after workup. The reaction of 1 with 2 equiv of KC8 and 1 equiv of 2.2.2-cryptand in tetrahydrofuran results in formation of the uranium(III) acetylide complex [K(2.2.2-cryptand)][U(CCH)(NR2)3] (3). Thermolysis of 1 or 2 results in formation of the bimetallic dicarbide complexes [{An(NR2)3}2(μ,η1:η1-C2)] (6, An = U; 7, An = Th), whereas the reaction of 1 with [Th{N(R)(SiMe2 CH2)}(NR2)2] results in the formation of [U(NR2)3(μ,η1:η1-C2)Th(NR2)3] (8). The 13C NMR chemical shifts of the α-acetylide carbon atoms in 2, 5, and 7 exhibit a characteristic spin–orbit-induced downfield shift, due to participation of the 5f orbitals in the Th–C bonds. Magnetism measurements demonstrate that 6 displays weak ferromagnetic coupling between the uranium(IV) centers (J = 1.78 cm–1).

“…Quantifying the extent of covalent bonding involving the actinide (An) 5f shell and different donor ligands is at the forefront of actinide chemistry research. − Actinide selectivity of extraction reagents is typically associated with a degree of 5f covalent bonding when compared to 4f bonding of the lanthanide (Ln) analogues. − Identifying and quantifying covalency in the An–ligand bonding is therefore essential for solving practical problems encountered, for instance, in the nuclear fuel cycle. − 5f covalency is also a fascinating topic on its own that has attracted much interest in the chemistry community, as evidenced by many publications (refs − and other articles cited herein represent a selection).…”

Section: Introductionmentioning

confidence: 99%

Covalency of Trivalent Actinide Ions with Different Donor Ligands: Do Density Functional and Multiconfigurational Wavefunction Calculations Corroborate the Observed “Breaks”?

Sergentu

Feng

et al. 2021

Self Cite

A comprehensive ab initio study of periodic actinide−ligand bonding trends for trivalent actinides is performed. Relativistic density functional theory (DFT) and complete activespace (CAS) self-consistent field wavefunction calculations are used to dissect the chemical bonding in the [AnCl 6 ] 3− , [An-(CN) 6 ] 3− , [An(NCS) 6 ] 3− , [An(S 2 PMe 2 ) 3 ], [An(DPA) 3 ] 3− , and [An(HOPO)] − series of actinide (An = U−Es) complexes. Except for some differences for the early actinide complexes with DPA, bond orders and excess 5f-shell populations from donation bonding show qualitatively similar trends in 5f n active-space CAS vs DFT calculations. The influence of spin−orbit coupling on donation bonding is small for the tested systems. Along the actinide series, chemically soft vs chemically harder ligands exhibit clear differences in bonding trends. There are pronounced changes in the 5f populations when moving from Pu to Am or Cm, which correlate with previously noted "breaks" in chemical trends. Bonding involving 5f becomes very weak beyond Cm/Bk. We propose that Cm(III) is a borderline case among the trivalent actinides that can be meaningfully considered to be involved in ground-state 5f covalent bonding.