Question

1. In what regard do the electronic structures of singlet oxygen and triplet oxygen differ from each other (write MO energy schemes) 8 pts

Answer 1

Singlet oxygen, systematically named dioxygen(singlet) and dioxidene, is a gaseous inorganic chemical with the formula O=O which is in a quantum state where all electrons are spin paired. It is kinetically unstable at ambient temperature, however the rate of decay is slow.

Wheras

Triplet oxygen, ³O₂, refers to the S = 1 electronic ground state of molecular oxygen (dioxygen). It is the most stable and common allotrope of oxygen. Molecules of triplet oxygen contain two unpaired electrons, making triplet oxygen an unusual example of a stable and commonly encountered diradical.

According to MOT,

Molecular Orbital Molecular Orbital Molecular Orbital 0930 Oxygen Oxygen Oxygen Oxygen Oxygen Oxygen 2p 2p π. 2s σ ' o,

In the above diagram, two singlet excited states and triplet ground state of molecular dioxygen. Shown are three electronic configurations of the molecular orbitals (MOs) of molecular oxygen, O₂. From left to right, the diagrams are for: ¹Δ_g singlet oxygen (first excited state), ¹Σ+
g singlet oxygen (second excited state), and ³Σ−
gtriplet 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 three states only differ in the occupancy and spin states of electrons in the two degenerate π* antibonding orbitals.