Carbon-hydrogen bond activations and their subsequent functionalisation have long been an important target in chemistry because C–H bonds are ubiquitous throughout nature, making C–H derivatisation reactions highly desirable. The selective and efficient functionalisation of this bond into many more useful carbon-element bonds (for example, C–B, C–Si, C–O and C–S bonds) would have many uses in pharmaceutical and bulk chemical synthesis. Activation of the C–H bond is, however, challenging due to the high strength and low bond-polarity of this bond rendering its cleavage unfavourable. With the correct choice of reagents and systems, especially those utilising directing groups, kinetically and thermodynamically favourable catalytic processes have been developed. However, a key remaining challenge is the development of undirected, intermolecular reactions using catalysts that are both selective and active enough to make useful processes. In this review, the progress towards optimising Group 9 C–H activation catalysts is discussed, particularly focusing on undirected reactions that are kinetically more difficult, starting with a brief history of C–H activation, identifying the importance of auxiliary ligands including the nature of anionic ligand (for example, cyclopentadienyl, indenyl, fluorenyl and trispyrazolylborate) and neutral ligands (such as phosphines, carbonyl, alkenes and N-heterocyclic carbenes (NHCs)) that contribute towards the stability and reactivity of these metal complexes. The tethering of the anionic ligand to strong σ-donating ligands is also briefly discussed. The focus of this review is primarily on the Group 9 metals rhodium and iridium, however, C–H activation using Group 8 and 10 metals are compared where useful. The most recent advances in this field include the development of C–H borylation of many small hydrocarbon substrates such as arenes, heterocycles and n-alkanes as well as the more challenging substrate methane.

The synthesis of platinum-cobalt nanocrystals (NCs) using colloidal solvothermal techniques is well understood. However, for monodisperse NCs to form, high temperatures and environmentally detrimental solvents are needed. We report a room temperature, aqueous method of platinum-cobalt NC synthesis using electrochemical reduction as the driving force for nucleation and growth. It is found that colloidal NCs will form in both the presence and absence of surfactant. Additionally, we report a monodisperse electrochemical deposition of NCs utilising a transparent conducting oxide electrode. The methods developed here will allow for a synthetic method to produce nanocatalysts with minimal environmental impact and should be readily applicable to other NC systems, including single- and multi-component alloys.

Johnson Matthey’s annual review of the platinum group metal (pgm) markets was published on 15th May 2023, providing an outlook for pgm supply and demand for 2023. The report contains a comprehensive review of developments in the automotive market, covering production and powertrain trends and their implications for pgm use as well as an update on future emissions legislation. It also features an in-depth discussion of the ruthenium and iridium markets in view of increasing interest in the use of these metals in the net zero transition.

Platinum has only been known to Europe since the 16th century. This was impure platinum, found as grains of native metal in alluvial deposits and comprising mainly platinum alloyed with the other five platinum group metals. They were exploited by pre-Colombian native populations of Ecuador and Colombia. In more recent times, the use of platinum in jewellery dates from the late 19th or early 20th centuries, often as a basis for diamond (and other precious gemstone) jewellery. Early jewellery alloys tended to be based on the existing industrial alloys and comparatively little development of specific jewellery alloys was carried out. Its acceptance as a hallmarkable jewellery metal came in 1975 when, with wider availability of the metal, platinum was promoted as a high-value jewellery metal. Platinum jewellery started to grow in popularity, mainly at 950 and 900 fineness qualities. Since that time there has been alloy development specifically for jewellery application and tailored to the requirements of different manufacturing technologies. This review examines the evolution of platinum jewellery alloys over the past century against the challenges presented in developing improved alloys for jewellery application. There has been a substantial increase in alloy development over the past 30 years, particularly focused on improved investment (lost wax) casting alloys as well as better mechanical properties.