Oxygen first ionization potential

The spectra and calculations all led to the conclusion that there is an usually large interaction between both the 7T and lone-pair orbitals in the carbonyl portion of the molecule with the n and a orbitals of the olefin portion. The first ionization potential (9.57 eV) involves ionization of an electron from the oxygen lone pair, whereas the second (11.19 eV) involves ionization of an electron from the olefin rr-bond. The most vertical ionization is from the 7 ax MO (16.11 eV), the second lone-pair orbital on oxygen. 

The effect of substituent groupings upon the first ionization potential of, at least, the aliphatic aldehydes and ketones does not seem to provide clear evidence for a choice between loss of a 7r-electron from the C=0 double bond or one of the oxygen lone-pair electrons. Concordant data for the homologous series of aliphatic ketones have been obtained by... 

On the assumption that all the reported aldehyde first ionization potentials refer to the oxygen lone-pair electrons Cook (1958) has classified the effect of substituents into two classes, A and B, according to whether inductive or resonance effects predominate. Two different linear correlations (Fig. 14) were found between ionization potential and the carbonyl stretching frequency. Anomalies were noted for diacetyl, benzaldehyde and mesityl oxide, ascribed in the last instance to noncoplanarity interfering with resonance. It seems more likely, however, that in these cases the first ionization potential refers to 7r-electrons and higher values for the lone-pair electrons (as yet undetermined) might remove the anomalies. 

Bis(arene) [M(jj6-C6H3R3)2] niobium (R = H3, H2Me or 1,3,5-Me3), and less stable tantalum derivatives (R = H3) were prepared in a similar way.714 They are extremely sensitive to oxygen, but relatively stable to water. The photoelectron spectra of the volatile bis(i76-arene) niobium display low values for the first ionization potentials (5.18-5.57 eV), indicating that the compounds are electron rich. The IR spectra of [Nb(C6H3R3)2] (R = H, Me) in an argon matrix at 80 K are in agreement with a symmetrical sandwich structure. 

The spontaneous oxidation of molecular oxygen and of atomic xenon, each of which has a first ionization potential of 281 kcal. mole , by platinum hexafluoride, has estabhshed the remarkable oxidizing power of the hexafluoride. None of the other third-transition-series hexafluorides will oxidize these species. Since it is well established - that the platinum hexafluoride-oxygen adduct is the salt Oj+[PtFe] , the lattice energy of which is estimated, employing Kapustinskii s second equation to be 125 kcal. moIe, the electron affinity of the PtF, molecule is required to be >156 kcal. mole, to ar count for the observed exothermic reaction [Pg.244]

The product is a colorless liquid at room temperature that fumes in air and is quickly colored brown if impure or on exposure to oxygen and moisture. It is a monomer in solution, showing rapid inter- and intramolecular proton exchange. H and C NMR indicate a high negative charge at the ylidic carbon. According to infrared/Raman studies the P=C bond order is about 1.6. The first ionization potential is extremely low (6.8 eV). The gas-phase structure shows a short P=C bond (1.60 A). ... 

Because of the structure, the molecule is susceptible to both nucleophilic and electrophilic attack through carbon and oxygen centers respectively. The first ionization potential of carbon dioxide (13 eV) is higher compared to that of water (12.6) and ammonia (10) [21], This indicates the noticeable electrophilicity of the central carbon atom. 

Compounds with Oxygen.—From photoionization mass spectrometry of F2O it has been deduced that the adiabatic first ionization potential is at 13.11 . 0.01 eV and also that the appearance potential of OI (0 K) has an upper limit of 14.44 eV, which is considerably less than the electron-impact value of 15.8 eV. These results imply that A/ff (OF) = 26.1 2.3 kcal mol and... 

Relative differences between S 2p3/2 and O 1 s ionization potentials show a characteristic separation for oxygen-bound and sulphur-bound sulphoxides. It is clearly shown in Table 20 that sulphur-bound complexes have (O 1 s-S 2p3/2) relative shifts of 365.0 eV, while oxygen-bound complexes have relative shifts of 365.8 eV. Infrared and X-ray crystallographic results also show that most neutral platinum and palladium dialkyl sulphoxide complexes contain metal-sulphur rather than metal-oxygen bonds, while first-row transition metals favour oxygen-bonded sulphoxide. 

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