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
Alkaline battery With mercury content reduced by law and improvements in the purity and consistency of materials, manufacturers have reduced the mercury content in modern cells. In an alkaline battery, the negative electrode is zinc and the positive electrode is manganese dioxide (MnO). The alkaline electrolyte of potassium hydroxide is not part of the reaction, only the zinc and MnO are consumed during discharge. The alkaline electrolyte of potassium hydroxide remains, as there are equal amounts of OH consumed and produced. The half-reactions are: Overall reaction: The chemical energy is stored mostly in the zinc metal, whose cohesive free energy per atom