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In chemistry, a superoxide is a compound that contains the superoxide ion, which has the chemical formula O − 2. [1] The systematic name of the anion is dioxide(1−).The reactive oxygen ion superoxide is particularly important as the product of the one-electron reduction of dioxygen O 2, which occurs widely in nature. [2]
[1] [2] [3] Introduced by Gilbert N. Lewis in his 1916 article The Atom and the Molecule, a Lewis structure can be drawn for any covalently bonded molecule, as well as coordination compounds. [4] Lewis structures extend the concept of the electron dot diagram by adding lines between atoms to represent shared pairs in a chemical bond.
Triplet oxygen, 3 O 2, refers to the S = 1 electronic ground state of molecular oxygen (dioxygen). Molecules of triplet oxygen contain two unpaired electrons, making triplet oxygen an unusual example of a stable and commonly encountered diradical: [2] it is more stable as a triplet than a singlet.
In cases where there is an ETC overload, part of the electron flow is diverted from ferredoxin to O 2, forming the superoxide free radical (by the Mehler reaction). In addition, electron leakage to O 2 can also occur from the 2Fe-2S and 4Fe-4S clusters in the PSI ETC.
Molecular orbital diagram of two singlet excited states as well as the triplet ground state of molecular dioxygen. From left to right, the diagrams are for: 1 Δ g singlet oxygen (first excited state), 1 Σ + g singlet oxygen (second excited state), and 3 Σ − g triplet oxygen (ground state). The lowest energy 1s molecular orbitals are ...
Atomic oxygen (O 1), a free radical. Singlet oxygen (O * 2), one of two metastable states of molecular oxygen. Tetraoxygen (O 4), another metastable form. Solid oxygen, existing in six variously colored phases, of which one is octaoxygen (O 8, red oxygen) and another one metallic (ζ-oxygen).
Free oxygen began to outgas from the oceans 3–2.7 billion years ago, reaching 10% of its present level around 1.7 billion years ago. [ 89 ] [ 91 ] The presence of large amounts of dissolved and free oxygen in the oceans and atmosphere may have driven most of the extant anaerobic organisms to extinction during the Great Oxygenation Event ...
2), a MO diagram may show one of the identical bonds to the central atom. For other polyatomic molecules, an MO diagram may show one or more bonds of interest in the molecules, leaving others out for simplicity. Often even for simple molecules, AO and MO levels of inner orbitals and their electrons may be omitted from a diagram for simplicity.