Platinum Characteristics

Physical

As a pure metal, platinum is silvery-white, lustrous, ductile, and malleable. It does not oxidize at any temperature, although it is corroded by halogens, cyanides, sulfur, and caustic alkalis. Platinum is insoluble in hydrochloric and nitric acid, but dissolves in aqua regia to form chloroplatinic acid, H₂PtCl₆. Platinum’s resistance to wear and tarnish is well suited for making fine jewelry. The metal has an excellent resistance to corrosion and high temperature and has stable electrical properties. All of these characteristics have been exploited for industrial applications.

Chemical

The most common oxidation states of platinum are +2, and +4. The +1 and +3 oxidation states are less common, and are often stabilized by metal bonding in bimetallic (or polymetallic) species. As is expected, tetracoordinate platinum(II) compounds tend to adopt 16-electron square planar geometries. While elemental platinum is generally unreactive, it dissolves in aqua regia to give soluble hexachloroplatinic acid (“H₂PtCl₆“, formally (H₃O)₂PtCl₆·nH₂O )

Pt + 4 HNO₃ + 6 HCl → H₂PtCl₆ + 4 NO₂ + 4 H₂O

As a soft acid, platinum has a great affinity for sulfur, such as on dimethyl sulfoxide (DMSO); numerous DMSO complexes have been reported and care should be taken in the choice of reaction solvent.

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