Rhenium trioxide ReO3

Rhenium trioxide has an unusually low electrical resistivity compared to common oxides. Similar to metals, the resistivity decreases with decreasing temperature. At 300 K, the resistivity is 100.0 nΩ·m, but at 100 K, it drops to 6.0 nΩ·m. Rhenium trioxide is chemically inactive. Insoluble in water, dilute hydrochloric acid and dilute sodium hydroxide, but soluble in concentrated nitric acid and oxidation into high rhenic acid, in the case of concentrated alkali disproportionation, there is no rhenium (VI) acid in aqueous solution. Rhenium trioxide is disproportionated to Re2O7 and ReO2 when heated above 300℃ in vacuum.

Rhenium trioxide or rhenium oxide (VI) is an oxide of rhenium, the chemical formula ReO3. It is a red solid with a metallic luster and is the only stable trioxide among the VIIB group of elements.