The modes of action of the commercial solvent extractants used in extractive hydrometallurgy are classified according to whether the recovery process involves the transport of metal cations, Mⁿ⁺, metalate anions, MX_x ⁿ⁻, or metal salts, MX_x into a water-immiscible solvent. Well-established principles of coordination chemistry provide an explanation for the remarkable strengths and selectivities shown by most of these extractants. Reagents which achieve high selectivity when transporting metal cations or metal salts into a water-immiscible solvent usually operate in the inner coordination sphere of the metal and provide donor atom types or dispositions which favour the formation of particularly stable neutral complexes that have high solubility in the hydrocarbons commonly used in recovery processes. In the extraction of metalates, the structures of the neutral assemblies formed in the water-immiscible phase are usually not well defined and the cationic reagents can be assumed to operate in the outer coordination spheres. The formation of secondary bonds in the outer sphere using, for example, electrostatic or H-bonding interactions are favoured by the low polarity of the water-immiscible solvents.

This article reviews recent progress in the exploitation of carbon dioxide as a chemical feedstock. In particular, the design and development of molecular complexes that can act as catalysts for the electrochemical reduction of CO₂ is highlighted, and compared to other biological, metal- and non-metal-based systems.

Rapid global technological development has led to the rising production of electronic waste that presents both challenges and opportunities in its recycling.

The uranyl ion, [U^VIO₂]²⁺, possesses rigorously trans, strongly covalent, and chemically robust U-oxo groups. However, through the use of anaerobic reaction techniques, both one- and two-electron reductive functionalization of the uranyl oxo groups has been discovered and developed. Prior to 2010, this unusual reactivity centered around the reductive silylation of the uranyl ion which entailed conversion of the oxo ligands into siloxy ligands and reductive metalation of the uranyl oxo with Group 1 and f-block metals. This review surveys the large number of new examples of reductive functionalization of the uranyl ion that have been reported since 2010, including reductive borylation and alumination, metalation with d- or f-block metals, and new examples of reductive silylation. Other examples of oxo-group functionalization of [U^VIO₂]²⁺ that do not involve reduction, mainly with Group 1 cations, are also covered, along with new advances in the photochemistry of the uranyl(VI) ion that involve the transient formation of formally uranyl(V) [U^VO₂]⁺ ion.