Occurrence and Uses
Rhenium (Re) is found in the combined state in platinum ores, gadolinite, molybdenite (MoS2) and columbite. It is found in some sulphide ores. It is a rare element making up about 0.001 ppm of the Earth’s crust.
Rhenium is used in electron tubes and in semiconductor applications. It is also used as a highly selective catalyst for hydrogenation and dehydrogenation. Rhenium-tagged antibodies have been used experimentally to treat adenocarcinomas of the colon, lung and ovary. Rhenium is used in medical instruments, in high-vacuum equipment, and in alloys for electrical contacts and thermocouples. It is also used for plating of jewellery.
Rhenium is alloyed with tungsten and molybdenum to improve their workability.
Chronic toxic manifestations are not known. Some compounds, such as rhenium hexafluoride, are irritating to the skin and eye. In experimental animals, inhalation of rhenium dust causes pulmonary fibrosis. Rhenium VII sulphide ignites spontaneously in air and emits toxic fumes of oxides of sulphur when heated. Hexamethyl rhenium presents a serious explosion hazard and should be handled with extreme caution.