The chemistry of actinide molecules and materials has shown remarkable conceptual advancements in the past decade illustrating their unique reactivity profiles, when compared with lanthanides and transition elements, but there are still some challenging questions on the intriguing stability of low valent states and the significant role of 5f orbitals in bonding and reactivity of actinides. The distinctive electronic flexibility of actinide centers makes them potential catalysts for heterogeneous molecular transformations because of the kinetic lability of their coordination states and facile switching among oxidaton states. Actinide-enabled chemical transformations such as the six-electron reduction of dinitrogen into two reactive ammonia molecules or four-electron oxidation of water into oxygen under mild conditions are promising pathways in the quest of high-efficiency heterogeneous catalysts. This Review provides a comprehensive account on actinide-mediated catalytic transformation of small molecules such as CO, CO2, N2, O2, H2O, CH4, HCl, and NH3. The emphasis is placed on the emerging phenomena in actinide-based solid catalysts and controlled synthesis of nanostructured actinide materials as pristine and substrate-grown phases. The mechanistic investigations highlight the influence of the 5f electrons in multielectron transfer reactions and the propensity of actinide centers to achieve higher oxidation states that defines the surface termination in actinide oxides. Finally, the status and perspectives of actinide-containing materials beyond the nuclear fuel applications is discussed, underlining their exciting chemistry and unexplored potential toward alternative catalytic energy production processes.

A new heteroleptic Ir(I) compound exhibiting high volatility and defined thermal decomposition under CVD conditions is reported. The new iridium precursor [(COD)Ir(ThTFP)] (COD = cyclooctadiene, ThTFP = (Z)-3,3,3-trifluoro-1-(thiazol-2-yl)prop-1-en-2-olate) unifies both reactivity and sufficient stability through its heteroleptic constitution to provide a precise control over compositional purity in CVD deposits. The solution integrity of the monomeric Ir(I) complex was investigated by 1D and 2D NMR spectroscopy and EI mass spectrometry, whereas the molecular structure was confirmed by single-crystal diffraction. CVD experiments demonstrated the suitability of the iridium compound for an atom-efficient (high molecule-to-precursor yield) gas-phase deposition of nanocrystalline iridium films that could be converted into crystalline iridium dioxide upon heat treatment to demonstrate their electrocatalytic potential in the oxygen evolution reaction.

New heteroleptic rhenium­(I) compounds, [fac-Re­(I)­(CO)3(L)] (e.g., L= tfb-dmpda, (N,N-(4,4,4-trifluorobut-1-en-3-on)-dimethyl propylene diamine)), containing anionic and neutral ligands act as efficient precursors to grow polycrystalline rhenium nitride (ReN) films by their vapor phase deposition at 600 °C. Deposition of ReN films under an external magnetic field showed an orientation effect with preferred growth of crystallites along ⟨100⟩ direction. Rhenium complexes reported here unify high stability and reactivity in a single molecule through a Janus-type coordination around a Re center, constituted by a chelating tridentate ligand and three carbonyl groups imparting a facial geometry. Single-crystal diffraction analysis confirmed the structural integrity of the new rhenium compounds. The rigidity of molecular framework was validated in solution via 1D and 2D NMR spectroscopy, in the gas phase via mass spectrometry, and in the solid-state by thermogravimetric analysis and differential scanning calorimetry studies. The analytical data showed that pre-existent Re–N bonds in [fac-Re­(I)­(CO)3(L)] facilitated low-temperature formation of crystalline ReN deposits confirmed by grazing angle X-ray diffraction analysis. The surface chemical composition and the uniformity of microstructure were provided by X-ray photoelectron spectroscopy (XPS) and scanning and transmission electron microscopy (SEM/TEM), respectively.

New heteroleptic iridium compounds exhibiting high volatility and defined thermal decomposition behavior were developed and tested in plasma-enhanced chemical vapor deposition (PECVD). The iridium precursor [(COD)Ir(TFB-TFEA)] (COD = 1,5-cyclooctadiene; TFB-TFEA = N-(4,4,4-Trifluorobut-1-en-3-on)-6,6,6-trifluoroethylamin) unifies both reactivity and sufficient stability through its heteroleptic constitution to offer a step-by-step elimination of ligands to provide high compositional purity in CVD deposits. The substitution of neutral COD ligands against CO groups further increased the volatility of the precursor. PECVD experiments with unambiguously characterized Ir compounds (single crystal X-ray diffraction analysis) demonstrated their suitability for an atom-efficient (high molecule-to-precursor yield) gas phase deposition of amorphous iridium oxide (IrOx) phases. Thin films of IrOx were well suited as electrocatalyst in oxygen evolution reaction so that an efficient coupled system in combination with solar cells is viable to perform water-splitting reaction without external bias.

A new Cu(I) precursor, [(COD)Cu(TFB-TFEA)] (COD = 1,5-cyclooctadiene, TFB-TFEA = N-(4,4,4-trifluorobut-1-en-3-on)-6,6,6-trifluoroethylamin) with high volatility and clean thermal decomposition pattern was tested in thermal and plasma-assisted chemical vapor deposition (CVD). The...