Platinum Metals Review - Volume 53, Issue 4, 2009

The Pd(I) dimer [Pd(μ-Br)(^tBu3P)]2is one of the best third-generation cross-coupling catalystsfor carbon–carbon and carbon–heteroatom coupling reactions. Information on its characterisation and handling are presented, including its decomposition mechanism in the presence of oxygen. The catalytic activity of [Pd(μ-Br)(^tBu3P)]2is higher than either (^tBu3P)Pd(0) or the in situ generated catalyst system based on Pd2(dba)3with ^tBu3P. Examples of suitable reactions for which the Pd(I) dimer offers superior performance are given.

New palladium-aluminium-based alloys with promising potential for application in the areas of jewellery and watchmaking are presented. Aparticular emphasis is placed on the mechanical behaviour of ternary palladium-aluminium-ruthenium (PdAlRu) alloys with 95 wt.% Pd. The new alloys combine high plasticity with high hardness relative to common Pd alloys. The low work-hardening rate enables cold working in excess of 95% reduction without intermediate annealing. The hardness (Vickers pyramid indentation) ranges from 100 HV to 300 HV in the annealed condition, depending on the Al:Ru ratio. Their whiteness in terms of colour coordinates is compared with platinum and white gold. The feasibility of porcelain fusion to PdAlRu for decorative purposes is also demonstrated.

Some fifty years ago Donald McDonald wrote in Platinum Metals Review on ‘The History of the Melting of Platinum’(1) and Leslie B. Hunt marked the event’s bicentenary in ‘The First Real Melting of Platinum: Lavoisier’s Ultimate Success with Oxygen’(2), which is also covered in the invaluable “A History of Platinum and its Allied Metals” (3). The topic is revisited and extended here, showing how oxygen, first isolated by Joseph Priestley and Carl Wilhelm Scheele, was used by Antoine Lavoisier to melt platinum. Work on the melting of the other platinum group metals (pgms) and modern methods for melting the metals are also discussed.