The limited availability of uranium (U) resources poses significant challenges to the advancement of nuclear energy. Recycling uranium from spent fuel is critical, but the coexistence of lanthanides (Ln) complicates the extraction process significantly. Here, we present an N/O ligand, (E)-N'-(pyridin-2-ylmethylene) picolinohydrazide (PYPH), designed for the selective recovery of U(VI) over Ln(III/IV) in acidic environments. 3,6-Bis(2-pyridinyl)-1,2,4,5-tetrazine (BPTZ) and N,N-dimethylformamide (DMF), when subjected to heat, gradually generate PYPH and formic acid in aqueous solution; this process can be employed for uranium recovery. This approach, known as the in situ reactive extraction technique, enhances capture capacity, selectivity, and acid resistance while effectively mitigating interference from Ce(IV). At pH 3 and 0.1 M HNO3, separation factors for the binary Ln(III/IV) and U(VI) systems exceeded 103 and 102, respectively, achieving purities exceeding 99%. Monocrystalline structure analysis revealed two-dimensional planar coordination complexes, demonstrating their exceptional selectivity. This study underscores the potential of PYPH in uranium recovery from spent fuel and proposes new avenues for developing innovative separation strategies for lanthanides and actinides (An) using structural and theoretical modeling.

A range of rare earth( iii ) 4-hydroxybenzoato (4hob) complexes has been prepared and structurally characterized. The La, Ce and Y complexes are good corrosion inhibitors for mild steel.

An entry from the Cambridge Structural Database, the world’s repository for small molecule crystal structures. The entry contains experimental data from a crystal diffraction study. The deposited dataset for this entry is freely available from the CCDC and typically includes 3D coordinates, cell parameters, space group, experimental conditions and quality measures.

An entry from the Cambridge Structural Database, the world’s repository for small molecule crystal structures. The entry contains experimental data from a crystal diffraction study. The deposited dataset for this entry is freely available from the CCDC and typically includes 3D coordinates, cell parameters, space group, experimental conditions and quality measures.

Redox transmetallation/protolysis reactions of rare earth metals, Hg(C6F5)2 and a formamidine (PhFormH = N, N'-(diphenyl)formamidine or DMFormH = N,N'-bis(2,4-dimethylphenyl)formamidine) in tetrahydrofuran (thf) or 1,2-dimethoxyethane (dme) were employed to synthesize a series of the rare earth N,N'-bis(aryl)for-mamidinate complexes. Accordingly, trivalent complexes with the composition [Ln(PhForm)3(thf)n].(solv.)m [n = 2, m = 0, Ln= La (1), Pr (2); n = 2, m = 0.5, solv = thf, Sm (3); n= 2, m = 1.5, solv. = PhMe, Ln= Nd (4); n= 2, m = 1.5, solv. = thf, Ln= Gd (5); n= 2, m = 3, solv. = thf, Ln= Tb (6), Dy (7), and Y (8); n= 1; m = 0, Ln= Ho (9), Er (10) and Lu (11)] or [Ln(DMForm)3(solv.)] [Ln = Sm (12), Gd (13), solv. = dme; Ln = Pr (14), Ho (15), solv. = DMFormH; Ln = Y (16), Lu (17), solv. = thf; Ln = Er (18), solv. = dmf; dmf = N,N-dime-thylformamide] were synthesized and characterized by X-ray crystallography. Complexes 1-8 have eight coordinate Ln metals with three chelating PhForm and two transoid thf ligands, whilst 9-11 are seven coordinate with a single thf ligand. Thus, there are three structural discontinuities, namely at Ho, Y, Er, the second of which occurs in defiance of a decrease in ion size. An investigation of catalytic reactivity of representative Ln complexes in the conversion of aldehydes into esters (Tishchenko reaction) revealed most have modest catalytic properties. [Y(PhForm)3(thf)2].3thf 7 and [Y(DMForm)3(thf)] 16 had the highest reactivity for their respective ligands, with 16 by far the most effective catalyst.

η6-Arene(iodidoaluminato)lanthanoid(II) complexes, {[Ln(η6-C6H5Me)(AlI4)2]}n [Ln = Sm, 1, Eu, 2, Yb, 3; C6H5Me = toluene] have been prepared by reactions of in situ generated aluminium triiodide with the corresponding lanthanoid metals and 1,2-diiodoethane in toluene (molar ratio : 2:1:1). Compounds 1-3 are polymeric and the lanthanoid(II) atom of 1 and 2 is coordinated by an η6–arene and three chelating k (I, I') tetraiodidoaluminate ligands, two of which are also bridging (LnI2AlI2Ln) and one is terminal. 3 is coordinated by an η6–arene, one terminal chelating k (I, I') and one chelating and bridging (YbI2AlI2Yb) tetraiodidoaluminate ligand, and one monodentate tetraiodidoaluminate ligand, which is also bridging (YbIAl(I)I2Yb). These are the first X-ray crystal structures of arene(tetrakisiodidoaluminato)lanthanoid(II) complexes. The first reported alkaline earth(II) (η6–arene)iodidoaluminate complexes, namely [Ca(η6-C6H5Me)(AlI4)2]n (4), {[Sr(η6-C6H5Me)(AlI4)2]n·nPhMe} (5), [Ba(η6-C6H5Me)2(AlI4)2] (6), [Ca(η6-C6H3Me3)(AlI4)2]n (7) and {[Sr(η6-C6H3Me3)(AlI4)2]n·0.5n(PhMe3)} (8) have also been obtained in an arene (toluene or mesitylene) solution by a similar method. Complex 4 is isocoordinate with 3, and 5 is isomorphous with 2. Complex 7 has eight coordinate Ca similar to 4, and complex 8 has nine coordinate Sr as in 5. Mononuclear ten coordinate complex 6 is the first example of a monomeric η6–arene sandwich complex of barium. The EuII bromidoaluminate complex {[Eu(η6-C6H5Me)(AlBr4)2]n·0.5nPhMe} (9) has been prepared from Eu metal, AlBr3, and BrCH2CH2Br in toluene and has a unit cell similar to 8 despite the different metal and arene.

The samarium(II) calix[4]pyrrolide complex [Sm2(N4Et8)(thf)4] (N4Et8 = meso-octaethylcalix[4]pyrrolide) undergoes selective oxidation of one SmII site on reaction with a range of metal carbonyls giving mixed valence Sm(II/III) complexes. Thus, reactions with TM(CO)6 (TM = Mo or Cr) entrap M2(CO)102- ions between two mixed valence hosts in [{(thf)2SmII(N4Et8)SmIII(thf)(μ-OC)TM(CO)4}2]·PhMe (TM = Mo, 1; Cr, 2), while W(CO)6 on a different stoichiometry traps W(CO)52- in [{(thf)2SmII(N4Et8)SmIII}2{(μ-OC)W(CO)4}]·PhMe 3 in which the isocarbonyl group is disordered over two sites. In contrast, [Sm2(N4Et8)(thf)4] reacts with dicobalt octacarbonyl, bis(cyclopentadienyl)tetracarbonyl diiron, and dimanganese decacarbonyl to give the mixed valence species [(thf)2SmII(N4Et8)SmIII(thf)(μ-OC)TM(CO)3]·2PhMe (TM = Co, 4; Fe, 5) and [(thf)2SmII(N4Et8)SmIII(thf)(μ-OC)Mn(CO)4]·1.5PhMe 6. However, both SmII sites of [Sm2(N4Et8)(thf)4] can be oxidized as its reaction with cyclooctatetraene (COT) yields the SmIII species [(thf)SmIII(N4Et8)SmIII(COT)] 7. The analogous EuII reagent, [Eu2(N4Et8)(thf)4] induces C-halogen activation of perfluorodecalin, hexachloroethane, and bromoethane to form the mixed oxidation state species [(thf)2EuII(N4Et8)EuIII(μ-X)]2 (X = F, 8; Cl, 9; Br, 10) despite the use of a sufficient reagent to oxidize both EuII sites. The synthetic potential of the halogenido complexes was illustrated by the reaction of 10 with sodium bis(trimethylsilyl)amide to give the mixed oxidation state [(thf)2EuII(N4Et8)EuIII(N(SiMe3)2)] 11.

eta(6)-Arene(iodido-/bromido-aluminato)lanthanoid(III) complexes, [Ln(eta(6)-C6H5Me)(AlI4)(3)] [Ln=La (1), Ce (2), Nd (3), (Gd) (4); C6H5Me=toluene], [Ln(eta(6)-C6H3Me3-1,3,5)(AlI4)(3)] [Ln=La (5), Ce (6), Pr (7), Nd (8), Sm (9), Gd (10); C6H3Me3-1,3,5=mesitylene], and [Ln(eta(6)-C6H5Me)(AlBr4)(3)] [Ln=La (11), Nd (12), Sm (13)] were prepared by reactions of aluminium triiodide or aluminium tribromide with the corresponding lanthanoid metals and 1,2-diiodoethane or 1,2-dibromoethane in an arene (toluene or mesitylene) solution (molar ratio : 6 : 2 : 3). The first X-ray crystal structures of arene(iodidoaluminato)lanthanoid(III) complexes are reported. The lanthanoid atom is coordinated by an eta(6)-arene and three chelating kappa(I, I')-tetraiodidoaluminato ligands. The tetrabromidoaluminate complexes have similar structures. The precatalyst 3 was treated with AlR3 (R=Me or iBu) to give [Nd(eta(6)-C6H5Me)(AlI3R)(3)] species in situ, which were then tested for catalytic activity towards isoprene polymerization. Although the resulting polyisoprene had a desirable high cis-1,4 content, the catalyst performance was well below known best performing systems and indicates that iodidoaluminates are the least favorable of the halogenidoaluminatolanthanoid(III) complexes.

Several new trivalent dinuclear rare earth 2,2'-methylenebis(6-tert-butyl-4-methylphenolate) (mbmp2- ) complexes with the general form [Ln2 (mbmp)3 (thf)n ] (Ln=Sm 1, Tb 2 (n=3), and Ho 3, Yb 4 (n=2), and a tetravalent cerium complex [Ce(mbmp)2 (thf)2 ] (5) have been synthesised by RTP (redox transmetallation/protolysis) reactions from lanthanoid metals, Hg(C6 F5 )2 and the biphenol mbmpH2 . These new complexes and some previously reported partially protonated rare earth biphenolate complexes [Ln(mbmp)(mbmpH)(thf)n ] react with lithium, aluminium, potassium and zinc organometallic reagents to form lanthanoid-main group heterobimetallic species. When reaction mixtures containing the Ln biphenolate complexes were treated with n-butyllithium, both molecular ([Li(thf)2 Ln(mbmp)2 (thf)n ] (Ln=La 6, Pr 7 (n=2) and Er 8, Yb 9, and Lu 10 (n=1)) and charge separated ([Li(thf)4 ][Ln(mbmp)2 (thf)2 ] (Ln=Y 11, Sm 12, Dy 13, and Ho 14) complexes were isolated. Treatment with trimethylaluminium also led to isolation of molecular ([AlMe2 Ln(mbmp)2 (thf)2 ] (Ln=Pr 15, Sm 16, and Tb 17)) and ionic [La(mbmp)(thf)5 ][AlMe2 (mbmp)] (18) complexes. One gadolinium-potassium ([K(thf)3 Gd(mbmp)2 (thf)2 ] (19)), and one ytterbium-zinc species ([ZnEtYb(mbmp)2 (thf)] (20)) were isolated from treatment of reaction mixtures with potassium bis(trimethylsilyl)amide and diethylzinc respectively.

An entry from the Cambridge Structural Database, the world’s repository for small molecule crystal structures. The entry contains experimental data from a crystal diffraction study. The deposited dataset for this entry is freely available from the CCDC and typically includes 3D coordinates, cell parameters, space group, experimental conditions and quality measures.

An entry from the Cambridge Structural Database, the world’s repository for small molecule crystal structures. The entry contains experimental data from a crystal diffraction study. The deposited dataset for this entry is freely available from the CCDC and typically includes 3D coordinates, cell parameters, space group, experimental conditions and quality measures.

A range of heteroleptic aluminium(III) formamidinate/formamidine complexes have been prepared involving metathesis reactions between AlX3 (X = Cl, Br, I) and alkali metal formamidinates. The mononuclear, bis-substituted complexes of the composition [Al(XylForm)2Cl] (XylForm = N,N′-bis(2,6-dimethylphenyl)formamidinate) (1), [Al(XylForm)2I]·PhMe (2), [Al(DippForm)2Cl] (DippForm = N,N′-bis(2,6-diisopropylphenyl)formamidinate) (3), [Al(DippForm)2I] (4), mono-substituted complexes of [Al(DippForm)Cl2(thf)] (5), [Al(DippForm)ClBr(thf)] (6), [Al(XylFormH)Br3] (7) and [Al(DippFormH)Br3] (8) were synthesised. [Al3(XylForm)2(µ3-O)(OH)Cl4]2·PhMe (9), was isolated in the reaction between K(XylForm) and AlCl3 as a trinuclear compound.

Abstract The metalation reactions of N,N’-bis-(2,4-dimethylphenyl)formamidine (DMFormH) and N,N’-bis-(phenyl)formamidine (PhFormH) with KN(SiMe3)2 or NaN(SiMe3)2 in toluene/1,2-dimethoxyethane (dme) resulted in the formation of [K(DMForm)(dme)]n (K1), [K2(PhForm)(N(SiMe3)2)]n (K2), [Na(DMForm)(dme)2] (Na1), and [Na(PhForm)(dme)]2 (Na2). Treatment of PhFormH with ZnEt2 or AlMe3 in toluene/tetrahydrofuran (thf) yielded [Zn4(PhForm)6O]·2.5thf (Zn1) and [Al(PhForm)3] (Al1), respectively. The potassium-formamidinate compounds (K1 and K2) are polymeric. K1 has six-coordinate potassium with additional C…K interactions. Reducing the steric effect of the formamidinate changes the formamidinate bonding mode. Thus, for potassium complexes, it led to both inter- and intra-molecular η6-arene-K binding in K2. With the sodium complexes, the structure changed from a six-coordinate monomer in [Na(DMForm)(dme)2] to a five-coordinate dimer in [Na(PhForm)(dme)]2 in which there is a μ 2-1κ(N,N’): 2κ (N) formamidinate binding mode. Zn1 has a pseudo-cubane oxide centered cage like structure, whereas Al1 is monomeric with six-coordinate aluminium and chelating formamidinate ligands. Graphical Abstract

A series of rare earth biphenolate complexes of the general form [Ln(mbmp)(mbmpH)(thf)3] (Ln = Y (1), Nd (2), Gd (3), Dy (4), Er (5), Tm (6) and Lu (7)) have been synthesised by redox transmetallation/protolysis (RTP) from the free rare earth metal, Hg(C6F5)2 and 2,2'-methylenebis(6-tert-butyl-4-methylphenol) (mbmpH2). The rare earth metal is six coordinate with one chelating biphenolate mbmp2- ligand and one unidentate monophenolate mbmpH- ligand. The yttrium complex, when crystallised from hot toluene or deuterated benzene, loses a coordinated thf and exhibits coordination through all three phenolate oxygen atoms, as well as the oxygen of the phenol, yielding two solvates [Y(mbmp)(mbmpH)(thf)2]·nsolv (solv = PhMe, n = 1 (8a) or C6D6, n = 2 (8b)). Of these rare earth complexes, the yttrium derivative (1) yielded the heterobimetallic complex [AlMe2Y(mbmp)2(thf)2] (9) when treated with trimethylaluminium, whereas all other complexes produced the transmetallation product [AlMe(mbmp)(thf)] (11). The dinuclear dysprosium complex [Dy2(mbmp)3(thf)3] (10) was isolated alongside 11 from the reaction of 4 with trimethylaluminium, suggesting trimethylaluminium instigates a redistribution reaction. The ROP activity of the mononuclear neodymium, dysprosium, lutetium, and aluminium complexes towards rac-lactide in toluene at 70 °C was found to be poor compared to rare earth complexes of monodentate aryloxides, but increased with increased rare earth ion size.