Carbonyl group, ionization potential

Also, the transannular interactions between amino and carbonyl groups in aminoke-tones, like 40-44, were studied by PES48. Pronounced stabilization of the n orbital and destabilization of the no orbital was established by comparison of the relevant ionization potentials with those of the corresponding monofunctional compounds. The shift of the no orbital was noticed as the best indicator of transannular n /jiQ=Q interaction and the maximum value was again found for the system with an eight-membered ring (41). 

Consideration of the relative donor abilities of nitrosyl, carbonyl, and phosphine groups as measured by their ionization potentials, provides an explanation for variations in the molecular ionization potentials of these complexes (103, 194). As shown in Table III (Section IX) the ionization potentials decrease on introduction of the phosphine ligand, and parallel the corresponding decrease in ionization potentials of the phosphine ligands. Similar correlations were made for vco and vNO in the infrared spectra. 

The growing demand for efficient chemical transformations and catalysts has inspired a few research groups in recent years to develop rare earth metal catalysts for organic synthesis [1, 2]. Triflates of rare earth metals are strong Lewis acids, which are stable in aqueous solution. Rare earth metal alkoxides on the other hand are of interest as Lewis bases, e.g. in the catalysis of carbonyl reactions, because of the low ionization potentials (5.4-6.4 eV) and electronegativities (1.1-1.3) of the 17 rare earth elements. Rare earth metal-alkali metal complexes in contrast show both Brpnsted-basic and Lewis-acidic properties. Impressive applications of such catalysts are presented and discussed here. 

Introduction of onsaturation between carbons 4 and 5 causes interaction of the donor-acceptor type involving the vr-electrons of the a,/3-unsaturated carbonyl system. Introduction of a,/3-unsaturation to the carbonyl group decreases the ionization potential of the carbonyl group or, in other words, increases the polarity of the carbonyl group. In terms of the resonance theory, the net change is an enlarged contribution of ionic structures, e.g.. 

Photoelectron spectra of benzothiete 209, the ketene derivative 210, (not isolated), and the naphthothiete 205 have been obtained and vertical ionization potentials reported. The unstable thiolactone 211 shows a carbonyl absorption at 1803 cm . ° The mass spectra of thietes usually show the molecular ion minus a hydrogen atom or other group as the most abundant species, thus suggesting the possible formation of a 4 -electron cation, for example, 212. ° ... 

However, all the free hydroxyl groups of cellulose are weakly ionizable, as is shown by the complete exchange of hydrogen for deuterium which takes place when it is immersed in deuterium oxide. The more acidic properties of the C2 hydroxyl group might be attributable to a permanent polarization of hydroxyl groups adjacent to a carbonyl or potential carbonyl group (see p. 293). 

Stener et al.66 studied carbon Is — n and oxygen Is — it as well as ionization potentials in carbonyl-containing molecules using the transition-state method. First, they considered the isolated CO molecule, and subsequently they studied the shifts when the carbonyl group was a part of a larger molecule. Furthermore, they used both density-functional and Cl calculations, and they calculated the oscillator strengths, too. As a representative example we show in Table 9 their results for some of these systems. It is immediately seen both that the density-functional calculations perform at least as well as the Cl calculations and also that the approximate transition-state method of Slater is accurate. It... 

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