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Single-atom (group 15 and group 16 anions) bridged dimetallic complexes of low oxidation state uranium provide a convenient route to implement multielectron transfer and promote magnetic communication in uranium chemistry, but remain extremely rare. Here we report the synthesis, redox and magnetic properties of N3−, O2−, and S2− bridged diuranium complexes supported by bulky aryloxide ligands. The U(IV)/U(IV) nitride [Cs(THF)8][(U(OAr)3)2(μ-N)], 1 could be prepared and characterized but could not be reduced. Reduction of the neutral U(IV)/U(IV) complexes [(U(OAr)3)2(μ-X)] A (X = O) and B (X = S) led to the isolation and characterization of the U(IV)/U(III) and U(III)/U(III) analogues. Complexes [(K(THF)4)2(U(OAr)2)2(μ-S)2], 5 and [K(2.2.2-cryptand)]2[(U(OAr)3)2(μ-S)], 6 are the first examples of U(III) sulphide bridged complexes. Computational studies and redox properties allow the reactivity of the dimetallic complexes to be related to their electronic structure. [ABSTRACT FROM AUTHOR]

The high stability of the + IVoxidation state limits thorium redox reactivity. Here we report the synthesis and the redox reactivity of two Th(IV) complexes supported by the arene‐tethered tris(siloxide) tripodal ligands [(KOSiR2Ar)3‐arene)]. The two‐electron reduction of these Th(IV) complexes generates the doubly reduced [KTh((OSi(OtBu)2Ar)3‐arene)(THF)2] (2OtBu) and [K(2.2.2‐cryptand)][Th((OSiPh2Ar)3‐arene)(THF)2](2Ph‐crypt) where the formal oxidation state of Th is +II. Structural and computational studies indicate that the reduction occurred at the arene anchor of the ligand. The robust tripodal frameworks store in the arene anchor two electrons that become available at the metal center for the two‐electron reduction of a broad range of substrates (N2O, COT, CHT, Ph2N2, Ph3PS and O2) while retaining the ligand framework. This work shows that arene‐tethered tris(siloxide) tripodal ligands allow implementation of two‐electron redox chemistry at the thorium center while retaining the ligand framework unchanged. [ABSTRACT FROM AUTHOR]

The silsesquioxane ligand (iBu)7Si7O9(OH)3 (iBuPOSSH3) is revealed as an attractive system for the assembly of robust polynuclear complexes of uranium(III) and allowed the isolation of the first example of a trinuclear U(III) complex ([U3(iBuPOSS)3]) that exhibits magnetic communication and promotes dinitrogen reduction in the presence of reducing agent. [ABSTRACT FROM AUTHOR]

The dinitrogen (N2) chemistry of lanthanides remains less developed compared to the d‐block metals and lanthanide‐promoted N2 functionalization chemistry in well‐defined lanthanide complexes remains elusive. Here we report the synthesis and characterization (SQUID, EPR, DFT, X‐Ray) of the siloxide supported heterobimetallic (Tm/K) complexes [{KTm(OSi(OtBu)3)3}2(μ‐η2 : η2‐N2)] (1) and [K3{Tm(OSi(OtBu)3)3}2(μ‐η2 : η2‐N2)] (2). Complex 2 provides a rare example of a metal complex of the triply reduced N23− radical. The structure of 2 differs from the few previously reported N23− complexes as it presents two Tm and three K cations binding the N23− radical, facilitating N2 functionalization. Notably, the K3Tm2‐bound N23− moiety reacts with excess H+ to form NH4Cl in 18 % yield, and with MeOTf at room temperature to yield the dimethyl hydrazido complex [K2{Tm(OSi(OtBu)3)3}2(μ‐(CH3)NN(CH3))] (3). Protonolysis of 3 yields MeHN−NMeH ⋅ 2HCl in 18 % yield. [ABSTRACT FROM AUTHOR]

Single-atom (group 15 and group 16 anions) bridged dimetallic complexes of low oxidation state uranium provide a convenient route to implement multielectron transfer and promote magnetic communication in uranium chemistry, but remain extremely rare. Here we report the synthesis, redox and magnetic properties of N 3- , O 2- , and S 2- bridged diuranium complexes supported by bulky aryloxide ligands. The U(IV)/U(IV) nitride [Cs(THF) 8 ][(U(OAr) 3 ) 2 (μ-N)], 1 could be prepared and characterized but could not be reduced. Reduction of the neutral U(IV)/U(IV) complexes [(U(OAr) 3 ) 2 (μ-X)] A (X = O) and B (X = S) led to the isolation and characterization of the U(IV)/U(III) and U(III)/U(III) analogues. Complexes [(K(THF) 4 ) 2 (U(OAr) 2 ) 2 (μ-S) 2 ], 5 and [K(2.2.2-cryptand)] 2 [(U(OAr) 3 ) 2 (μ-S)], 6 are the first examples of U(III) sulphide bridged complexes. Computational studies and redox properties allow the reactivity of the dimetallic complexes to be related to their electronic structure.

The high stability of the + IVoxidation state limits thorium redox reactivity. Here we report the synthesis and the redox reactivity of two Th(IV) complexes supported by the arene-tethered tris(siloxide) tripodal ligands [(KOSiR 2 Ar) 3 -arene)]. The two-electron reduction of these Th(IV) complexes generates the doubly reduced [KTh((OSi(O t Bu) 2 Ar) 3 -arene)(THF) 2 ] (2 OtBu ) and [K(2.2.2-cryptand)][Th((OSiPh 2 Ar) 3 -arene)(THF) 2 ](2 Ph -crypt) where the formal oxidation state of Th is +II. Structural and computational studies indicate that the reduction occurred at the arene anchor of the ligand. The robust tripodal frameworks store in the arene anchor two electrons that become available at the metal center for the two-electron reduction of a broad range of substrates (N 2 O, COT, CHT, Ph 2 N 2 , Ph 3 PS and O 2 ) while retaining the ligand framework. This work shows that arene-tethered tris(siloxide) tripodal ligands allow implementation of two-electron redox chemistry at the thorium center while retaining the ligand framework unchanged., (© 2023 Wiley-VCH GmbH.)

One tetrahedral and two trigonal prismatic cages with π-basic Au 3 (pyrazolate) 3 faces were obtained by connection of pre-formed gold complexes via dynamic covalent imine chemistry. The parallel arrangement of the Au 3 (pyrazolate) 3 complexes in the prismatic cages augments the interaction with π-acids, as demonstrated by the encapsulation of polyhalogenated aromatic compounds. The tetrahedral cage was found to act as a potent receptor for fullerenes. The structures of the three cages, as well as the structures of adducts with C 60 and C 70 , could be established by X-ray crystallography., Competing Interests: There are no conflicts to declare., (This journal is © The Royal Society of Chemistry.)