Electron affinity vertical

H. Han, M. B. Zimmt, Solvent-Mediated Electron Transfer - Correlation Between Coupling Magnitude and Solvent Vertical Electron Affinity , J. Am. Chem Soc 1998,120, 8001-8002. 

FIGURE 34.3 Correlation of the vertical electron affinity, calculated using Equation 34.36 at the PBE/aug-cc-pVTZ level, with experimental values. All values are in eV data are taken from Table 34.3. (Reprinted from De Proft, F., Sablon, N., Tozer, D.J., and Geerlings, P., Faraday Discuss., 135, 151, 2007. With permission.)... 

For reproducing as closely as possible diabatic conditions, we have fixed the Cl—Cl bondlength at its neutral equilibrium value. This way, the system depends on two parameters as shown in Figure 1. Previous experimental and theoretical studies on similar systems, [1,18] have shown that electron jump from Li to the acceptor molecule CI2, which has, once relaxed, a positive vertical electron affinity (see Table 1), is likely to take place at a distance d, (see the definition of this parameter in Figure 1) which is superior to the LiCl equilibrium distance (MP2 value 2.0425 A). The description of this phenomenon in terms of MO and states will be briefly recalled in the next section. 

The vertical electron affinity (EA) of acetone is given as —1.51 eV by Jordan and Burrow386. Lifshitz, Wu and Tiernan387 determine—among other compounds—the excitation function and rate constants of the slow proton transfer reactions between acclone-Ih, acetone-Dg and other ketones. The acetone enolate anion has been produced in a CO2 laser induced alkane elimination from alkoxide anions by Brauman and collaborators388-390. These show, e.g. that the methane elimination from t-butoxide anion is a stepwise process ... 

The vertical ionization energy and vertical electron affinity are (here ZPEs have not been taken into account, as they should nearly cancel in any case the significance of a calculated ZPE for the cation or anion at the geometry of the neutral is questionable, since the two vertical species are not stationary points) ... 

We have demonstrated that Nj may form a salt with Nj [5] although side-reactions like the formation of covalently bound N10 or loss of N2 from the anion may pose a problem. We found that the kinetic stability of Nj is decreased when charge is diminished by charge transfer from the anion. Since the vertical ionization potential of Nj (5.6 eV [5,11]) is lower than the vertical electron affinity of N5, we also explore derivatives of Nj that may have a larger ionization potential and/or greater kinetic stability. 

Vertical electron affinities of N5 and the CHN4 isomers in eV at EOM-CCSD/POL1// ... 

The vertical electron affinities of N5 and the phosphorus-substituted cations are given in Table 6. Most cations have electron affinities larger than 7.6 eV. Only the cations 5, 7, and 11 have electron affinities similar to that of Nj. They are candidates for formation of salts with very electronegative anions like AsFg, SbFj, or N5. The enthalpies of formation of the cations are given in Table 7. They vary between 221 kcal/mol for the PNP+--N2 complex 9 over 264 kcal/ mol for the 1,5-diphospha cation 11 to 354 kcal/mol for the linear cation 13. 

The high heat of formation of the N3 cation ( 350 kcal/mol) makes it very attractive as a component of high energy density materials (HEDMs). However, its large vertical electron affinity (vEA) of 6.1 eV poses a problem So far, the preparation of only NsAsFg, N ShF, and NjSb2Fu has been reported. The oxidation of Br2 (IP 10.5 eV) by N SbFj shows that N3 is also susceptible to nucleophilic attack by Lewis bases. Calculations on NjNj show that such a crystal may exist, but nucleophilic attach of the anion is a likely side-reaction. We think that less electronegative derivatives of N3 may be less sensitive to both reduction and nucleophilic attack. 

All but one CN30+ isomer have vertical electron affinities between 7.1 and 8.4 eV. The vEA of OC-N3 (14) is only slightly lower than that of N3. The bonds to the central atom are shorter than in Ns, suggesting increased kinetic stability towards unimolecular dissociation. It should be possible to isolate OCN3SbF since the corresponding N3 and N(CO)2 salts exist. 

The promotion gap is given by the difference between the vertical ionization energy of X - anions (1 ) and the vertical electron affinity of the cation (A +), leading to the following expression for the barrier ... 

Table 8. Vertical Electron Affinities (eV) of Some Alkynes as Determined by Electron Transmission Spectroscopy l46,1471...

From the ET spectra vertical electron affinities are obtained. However, for several reasons it would be interesting to know the adiabatic electron affinities, particularly since there might be a large difference between the vertical and the adiabatic electron affinities in these cycloalkynes. Therefore, electrochemical investigations were carried out to find additional evidence for the increased electron affinity. 

Fig. 4. Correlation Diagram for the Vertical Electron Affinities and Ionization Potentials of Some Linear Alkynes and Some Angle Strained Cyeloalkynes 146 147)...

Figure 5-3. Dependence of the vertical electron affinity (VEA in eV) of ammonia and water on the average total dipole moment in D) for clusters with different number of molecules (n). The dashed lines are fitting to the raw data with correlation coefficients r = 0.99 (water) and r = 0.98 (ammonia)...

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