Double electron affinity

The alkaline earth imides have a cubic, NaCl-type lattice and their lattice energies have been evaluated by A, P. Altshuller (4). Since the compressibilities were unknown he used the Born-Lande equation and adopted the value of n used by Sherman for the corresponding oxides. He did not incorporate a term to allow for the dispersion energy and found for the lattices energies of CaNH, SrNH and BaNH values of 787, 752 and 711 kcal/mole, respectively. Only the heat of formation of BaNH was available and from this a value of AH/ NH of 261 kcal/mole and hence a double electron affinity of —184 kcal/mole w as obtained. 

Concerning the general reaction Scheme 1, attention is restricted to two special areas A), cases where X is a carbon-centered radical and Y is an oxygen atom joined by a double bond to some center Z (Eq. 4), and B), cases where X is a hetero atom, in most cases oxygen centered radical and Y is a carbon (Eq. 5) [11]. One is then dealing with formation and heterolysis of a bond between a carbon- and a hetero-atom. Of the two, the hetero-atom is of course always more electron-affinic and therefore in the heterolysis the electron pair joining the two will go to the hetero-atom. 

The test set used for most comparisons in the present paper is Database/3 18), which was introduced elsewhere. It consists of 109 atomization energies (AEs), 44 forward and reverse reaction barrier heights (BHs) of 22 reactions, 13 electron affinities (EAs), and 13 ionization potentials (IPs). There are a total of 513 bonds among the 109 molecules used for AEs, where double or triple bonds are only counted as a single bond. Note that all ionization potentials and electron affinities are adiabatic (not vertical), i.e., the geometry is optimized for the ions... 

Addition of an alkyl nucleophile leads, due to the loss of one double bond, to a decrease of electron affinity and a concomitant negative shift of the reduction potential of about 100 to 150 mV per lost double bond. One possibility to compensate for this negative shift is the introduction of an electron-withdrawing substituent such as cyanide. Reaction of liCN or NaCN with Cjq at room temperature generates the monoadduct anion that can be quenched with various electrophiles [6]. 

Several effects can influence the electronic structure of Cjq upon metal complex formation. One is the removal of one double bond from the remaining 29 fullerene double bonds. As in any polyene system, this decreased conjugation is expected to raise the energy of the LUMO and therefore decreases the electron affinity of the system. Conversely, the d-orbital backbonding transfers electron density from the metal into n orbitals of the remaining double bonds, which also decreases the electron affinity. 

Energy levels of heavy and super-heavy (Z>100) elements are calculated by the relativistic coupled cluster method. The method starts from the four-component solutions of the Dirac-Fock or Dirac-Fock-Breit equations, and correlates them by the coupled-cluster approach. Simultaneous inclusion of relativistic terms in the Hamiltonian (to order o , where a is the fine-structure constant) and correlation effects (all products smd powers of single and double virtual excitations) is achieved. The Fock-space coupled-cluster method yields directly transition energies (ionization potentials, excitation energies, electron affinities). Results are in good agreement (usually better than 0.1 eV) with known experimental values. Properties of superheavy atoms which are not known experimentally can be predicted. Examples include the nature of the ground states of elements 104 md 111. Molecular applications are also presented. 

It would be very interesting to speculate on the behavior of the iso-electronic species NH and O atoms. From limited kinetic studies these appear to undergo addition to double bonds as well as abstraction type of reactions.21 22 However no definitive studies have been made on the existence of the insertion type of reaction which would be very much expected for both species, particularly for the O atom, in view of its fairly large electron affinity.8... 

Bicycio[m. .0]alkenes (25 in. n) with the double bond linking the bridgehead carbons are another class of relevant compounds. Enthalpy-of-formation data are available for the m = n = 1 case through analysis of gas-phase acidity and electron-affinity measurements76, and for m = 2, n = 2, 3 and 4 from hydrogenation data54 from reaction in a thermochemically innocuous hydrocarbon solvent. Parallelling the earlier transalkylation reactions (equation 14), perhaps the simplest comparison we can make is to use the enthalpy of the reaction of the bicyclic species with ethylene to form two mono-cyclic ones. 

Clearly, factors influencing electron-affinity of the fluorinated alkene, i.e. the influence of F or perfluoroalkyl (RP) as a substituent at the double-bond, are important to consider, as are the effects of these substituents on carbanion (3) stabilities. 

We have already shown that excitation energies can be diagrammatically decomposed to yield simpler quantities such as ionization potentials and electron affinities plus some remaining diagrams. MB-RSPT permits the use of this treatment for even more complex processes. In this section, we present the applicability of the theory to double ionizations observed in Auger spectra as well as excitations accompanying photoionization (shake-up processes) observed in ESCA and photoelectron spectroscopy. A detailed description of this approach is given in Refs.135,136. Here we shall present only the formal description. 

The first term in the curled brackets can be decomposed to quantities which have already been presented, i.e. ionization potentials, electron affinities, excitation energies, double ionization energies as well as certain remaining terms. This composite property of MB-RSPT might be of value for practical applications because the mentioned quantities can be calculated separately or even substituted for with experimental values. Therefore, to interpret such complicated spectra it is sufficient to calculate a particular class of diagrams. We believe that this is more economic than a Cl calculation of comparable accuracy. Moreover, it gives us a microscopic view of the problem in contrast to the global nature of the Cl calculation. 

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