Chemists have spent over a hundred years trying to make ambient temperature/pressure catalytic systems that could convert atmospheric dinitrogen to ammonia, or to directly to amines. A handful of successful d-block metal catalysts have been developed in recent years, but even binding of dinitrogen to an f-block metal cation is extremely rare. Here we report the first f-block complexes that can catalyse the reduction and functionalisation of molecular dinitrogen, and the first catalytic conversion of molecular dinitrogen to a secondary silylamine. Simple bridging ligands assemble two actinide metal cations into narrow dinuclear metallacycles that can trap the diatom while electrons from an externally-bound group 1 metal, and protons or silanes, are added enabling N 2 to be functionalised with modest but catalytic yields of six equivalents of secondary silylamine per molecule at ambient temperature and pressure.Many complexes of the d-block metals can bind the abundant dinitrogen molecule, but the conversion to products is very difficult, and only a few are capable of catalytic conversion. The most successful catalysts are based on Mo or Fe 1,2,3,4,5,6,7,8 , and convert the bound dinitrogen to NH 3 or N(SiMe 3 ) 3 , using compatible sources of reducing equivalents and protons or silyl electrophiles (e.g. KC 8 powder and lutidinium borates or Me 3 SiCl) 9,10 . The use of soluble metal catalysts offers direct routes to other functionalised organo-nitrogen molecules and further insight into the workings of the exceptional heterogeneous Haber-Bosch catalyst or the low-energy nitrogenase enzymes that directly make ammonia. 11,12,13,14,15,16,17 An emerging key feature of some of the most successful homogeneous systems is the ability of the complex to incorporate alkali metal cations that bring the reducing electrons to the nitrogen centres, providing additional coulombic interactions, and the capacity of the resulting multi-metallic framework to flex sufficiently to enable the N 2 coordination mode to change during reduction. 18,19,20,21,22 Binding of dinitrogen by any f-block metal ion is extremely rare. 23,24 The eight known actinide-dinitrogen complexes were all made by exploiting the strongly reducing

A library of new dinuclear Ce IV complexes of the type [NEt 4 ] 2 [Ce 2 X 6 (TP)(sol) 2 ] (X = Cl, ODipp, OSiMe 3 ; sol = py, THF), where TP represents a family of tetraphenolate ligands that control intermetallic distance, are readily made in good yields. The ligands strongly stabilize the cerium +4 oxidation state and allow the incorporation of alkylammonium co-cations in an 'ate' complex formulation that enables them to be used as soluble, single-component catalysts for the ring-opening copolymerization (ROCOP) of a variety of anhydrides and epoxides. High turnover frequencies (TOFs) are achieved with high ester linkage selectivity, low dispersities, and rates that are highly tunable by the intermetallic distance enforced by the TP ligand, demonstrating that a closely coupled di-Ce IV unit provides excellent rates of ROCOP catalysis, and that more generally, rare earth complexes deserve further attention as ROCOP initiators.

The photolytic activation of palladium(II) and platinum(II) complexes [M(BPI)(R)] (R = alkyl, aryl) featuring the 1,3-bis(2-pyridylimino)isoindole (BPI) ligand has been investigated in various solvents. In the absence of oxygen, the formation of chloro complexes [M(BPI)Cl] is observed in chlorinated solvents, most likely due to the photolytic degradation of the solvent and formation of HCl. The reactivity of the complexes toward oxygen has been studied both experimentally and computationally. Excitation by UV irradiation (365 nm) of the metal complexes [Pt(BPI)Me] and [Pd(BPI)Me] leads to distortion of the square-planar coordination geometry in the excited triplet state and a change in the electronic structure of the complexes that allows the interaction with oxygen. TD-DFT computational studies suggest that, in the case of palladium, the Pd(III) superoxide intermediate [Pd(BPI)(κ 1 -O 2 )Me] is formed and, in the case of platinum, the Pt(IV) peroxide intermediate [Pt(BPI)(κ 2 -O 2 )Me]. For alkyl complexes where metal−carbon bonds are sufficiently weak, the photoactivation leads to the insertion of oxygen into the metal−carbon bond to generate alkylperoxo complexes: for example [Pd(BPI)OOMe], which has been isolated and structurally characterized. For stronger M−C(aryl) bonds, the reaction of [Pt(BPI)Ph] with O 2 and light results in a Pt(IV) complex, tentatively assigned as the peroxo complex [Pt(BPI)(κ 2 -O 2 )Ph], which in chlorinated solvents reacts further to give [Pt(BPI)Cl 2 Ph], which has been isolated and characterized by scXRD. In addition to the facilitation of oxygen insertion reactions, UV irradiation can also affect the reactivity of other components in the reaction mixture, such as the solvent or other reaction products, which can result in further reactions. Labeling studies using [Pt(BPI)(CD 3 )] in chloroform have shown that photolytic reactions with oxygen involve degradation of the solvent.

Modular tetraphenolate ligands tethered with a protective arene platform (para-phenyl or para-terphenyl) are used to support mononuclear An(IV) (An = Th, U) complexes with an exceptionally large and open axial coordination site at the metal. The base-free complexes and a series of neutral donor adducts were synthesized and characterized by spectroscopies and single-crystal Xray diffraction. Anionic Th(IV) -ate complexes with an additional axial aryloxide ligand were also synthesized and characterized. The para-phenyl-tethered mononuclear complexes exhibit rare An(IV)−arene interactions, and the An(IV)−arene distance broadly increases with axial donor strength. The para-terphenyl-tethered complexes have almost no interaction with the arene base, isolating the central metal cation. Computational analysis of the mononuclear complexes and their reduced analogues, and Yb(III) congeners, as well as the effect of additional donor ligand binding, seek to elucidate the electronic structure of the metal−arene interactions and establish whether they, or their reduced or oxidized counterparts, could function as molecular qubits.