Oxygen, ground state energy

These data imply that kinetic barriers must exist in the interaction between catalyst and organic species that are not reflected in the ground state energy data presented. Otherwise there would be little hope of achieving any C-H transformation selectively either in the absence of oxygen (preferred reaction is element formation) or in the presence of oxygen (preferred reaction is total combustion). 

Table 3.1. Calculations of ground state energies for the oxygen molecule, E/Oj), for the oxygen atoms moved 2.0 nm apart, EjfO—O), and twice the energy of a single oxygen atom, E/20), plus O2 binding energies estimated as the difference between E, and each of the two calculations for separated atoms. The value determined experimentally is -5.2 eV. All calculations use the SV basis set. HF = Hartree-Fock, MP = Moller-Plesset. For the remaining rows see discussion in text.

When the triplet is an excited state, energy transfer occurs to form singlet oxygen. Ground state triplets react with oxygen by a spin-allowed process which, for carbenes in particular, produce carbonyl oxides [64], It seems that triplet nitrenes react with oxygen slowly. This will be discussed more fully later. Here we examine the products formed from reaction of photolysis of phenyl azide in the presence of oxygen. 

Electronic excitation from atom-transfer reactions appears to be relatively uncommon, with most such reactions producing chemiluminescence from vibrationaHy excited ground states (188—191). Examples include reactions of oxygen atoms with carbon disulfide (190), acetylene (191), or methylene (190), all of which produce emission from vibrationaHy excited carbon monoxide. When such reactions are carried out at very low pressure (13 mPa (lO " torr)), energy transfer is diminished, as with molecular beam experiments, so that the distribution of vibrational and rotational energies in the products can be discerned (189). Laser emission at 5 p.m has been obtained from the reaction of methylene and oxygen initiated by flash photolysis of a mixture of SO2, 2 2 6 (1 )-... 

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