Metal carbonyl 18-electron complexes is sometimes catalysed by catalytic amounts of oxidants, via electron-transfer. Metal carbonyls react with reducing agents such as metallic sodium or sodium amalgam to give carbonylmetalate (or carbonylate) anions: For iron pentacarbonyl, one obtains the tetracarbonylferrate with loss of CO: Mercury can insert into the metal-metal bonds of some polynuclear metal carbonyls: The CO ligand is often susceptible to attack by nucleophiles. For example, trimethylamine oxide and bistrimethylsilylamide convert CO ligands to CO and CN, respectively. In the "Hieber base reaction", hydroxide ion attacks the CO ligand to give a metallacarboxylic acid, followed by the release of carbon
Mercury cycle Mercury cycle The mercury cycle is a biogeochemical cycle involving mercury. Mercury is notable for being the only metal which is liquid at room temperature. It is a volatile metal and evaporates, though it takes quite a while to do so. Most natural mercury occurs as cinnabar, HgS. Here mercury (Hg) is bound very tightly to sulfur, but weathering slowly releases the mercury to the environment. There are also trace amounts of mercury in coal. Mining mercury or burning coal results in releasing mercury. Volcanoes and forest fires are also sources of mercury. Chlorine factories, among other sources, release mercury