Platinum Metals Review - Volume 49, Issue 3, 2005

There are numerous platinum jewellery alloys available today. Two commercially available general purpose alloys that are in common use by manufacturing platinum jewellers are platinum-5% copper and platinum-5% ruthenium. In South Africa, the copper alloy is normally preferred for casting because of its lower melting point and greater fluidity, while the ruthenium alloy is preferred for hand-working and machining, although some jewellers use either alloy for all applications. In order to provide a scientific basis to the differences in finish and workability, as experienced by jewellers, we set out to compare casting characteristics of platinum-copper and platinum-ruthenium jewellery alloys and look for any substantial differences between them. We also examine factors affecting their different characteristics, and how working conditions can be manipulated to optimise the performance of each alloy in jewellery manufacture.

Diesel engines have major roles in automotive and stationary applications, both large (heavy duty) and small (light duty). Diesel engines are energy efficient, but their NOx and particulate emissions present major obstacles to engine development. This selective review of the course "Diesel Particulates and NOx Emissions" reports the latest developments taking place in diesel technology: engine design, fuel injection systems, fuel, lubricants, turbochargers, aftertreatment, emissions and health effects, that impact on particulate and NOx emissions. The course is run by the University of Leeds, Energy and Resources Research Institute.

The vast family of ruthenium complexes with nucleophilic N-heterocyclic carbene (NHC) ligands is selectively discussed as an improved alternative to their parent diphosphane ruthenium counterparts previously applied in olefin metathesis reactions. The survey covers work done to-date on the ruthenium alkylidene, vinylidene, allenylidene and indenylidene complexes bearing imidazolin-2-ylidene and dihydroimidazolin-2-ylidene carbenes, as well as a number of immobilised ruthenium complexes having these types of ligands. Examples of chiral compounds complete the spectrum of NHC ruthenium complexes. Synthetic methods, catalytic properties and application profile in ring-closing metathesis, cross metathesis, ring-opening metathesis and metathesis polymerisation are highlighted.

A simple low cost hydrothermal method is described for producing thin films of porous platinum. The films are formed from [Pt(NH3)4]Cl2 and comprise platinum agglomerates ∼ 200–300 nm in size with internal grains of ∼ 20–60 nm.

The thermodynamic properties of platinum were reviewed here by the author in 1994. However, the use of superior values for the enthalpy of liquid platinum have resulted in a major revision of the thermodynamic values for the liquid phase. One consequence of the revision is that the boiling point at one atmosphere pressure is altered from 4125 K, as calculated in the 1994 paper, to 4149 K. Previously accepted values for solid platinum are not altered, and there are only very minor changes to the gaseous phase values as a result of using a new atomic weight for platinum and the CODATA 2002 recommended values of the fundamental constants.