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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 .
Singlet oxygen is the common name used for the two metastable states of molecular oxygen (O 2) with higher energy than the ground state triplet oxygen. Because of the differences in their electron shells, singlet oxygen has different chemical and physical properties than triplet oxygen, including absorbing and emitting light at different ...
g singlet oxygen (second excited state), and 3 Σ − g triplet oxygen (ground state). The lowest energy 1s molecular orbitals are uniformly filled in all three and are omitted for simplicity. The broad horizontal lines labelled π and π* each represent two molecular orbitals (for filling by up to 4 electrons in total).
The singlet oxygen reagent can be produced via photochemical activation of triplet oxygen (regular oxygen) in the presence of photosensitizers like rose bengal. Chemical processes like the reaction between hydrogen peroxide and sodium hypochlorite are also viable.
Oxygen is the third most abundant chemical element in the universe, after hydrogen and helium. [68] About 0.9% of the Sun's mass is oxygen. [19] Oxygen constitutes 49.2% of the Earth's crust by mass [69] as part of oxide compounds such as silicon dioxide and is the most abundant element by mass in the Earth's crust.
Stable, isolable, diradicals include singlet oxygen and triplet oxygen. Other important diradicals are certain carbenes, nitrenes, and their main-group elemental analogues. [7] Lesser-known diradicals are nitrenium ions, carbon chains, [8] and organic so-called non-Kekulé molecules in which the electrons reside on different carbon atoms.
Most molecules encountered in daily life exist in a singlet state because all of their electrons are paired, but molecular oxygen is an exception. [1] At room temperature, O 2 exists in a triplet state, which can only undergo a chemical reaction by making the forbidden transition into a singlet state. This makes it kinetically nonreactive ...
As in diboron, these two unpaired electrons have the same spin in the ground state, which is a paramagnetic diradical triplet oxygen. The first excited state has both HOMO electrons paired in one orbital with opposite spins, and is known as singlet oxygen. MO diagram of dioxygen triplet ground state