2-electron bond energy

Fig. 4.—Calculated one-electron bond energy-values (D/k, full curves) and squared bond strength values (S, dashed curves) for s-p hybridization.

The results of the calculation of one-electron bond energies for orbitals of the type wpis +... 

Fig. 6b.—Contour diagram of D/k (calculated one-electron bond energy divided by a constant) for s-p-d hybridization.

In sharp contrast to the stable [H2S. .SH2] radical cation, the isoelectron-ic neutral radicals [H2S.. SH] and [H2S. .C1] are very weakly-bound van der Waals complexes [125]. Furthermore, the unsymmetrical [H2S.. C1H] radical cation is less strongly bound than the symmetrical [H2S.. SH2] ion. The strength of these three-electron bonds was explained in terms of the overlap between the donor HOMO and radical SOMO. In a systematic study of a series of three-electron bonded radical cations [126], Clark has shown that the three-electron bond energy of [X.. Y] decreases exponentially with AIP, the difference between the ionisation potentials (IP) of X and Y. As a consequence, many of the known three-electron bonds are homonuclear, or at least involve two atoms of similar IP. 

The ab initio calculations of various three-electron hemibonded systems [122, 123] indicated that the inclusion of electron correlation corrections is extremely important for the calculation of three-electron bond energies. The Hartree-Fock (HF) error is found to be nonsystematic and always large, sometimes of the same order of magnitude as the bond energy. According to valence bond (VB) and MO theories, the three-electron bond is attributed to a resonance between the two Lewis structures... 

These two resonance hybrids are mutually related by charge transfer. Hib-erty, Shaik and co-workers [136] explained the HF bias in the three-electron bond energies in terms of two deficiencies ... 

Quantum chemical calculations (HMO) of certain tropylium and related carbenium ions (64JA5630) show that a nearly linear relationship exists between pKR and the excessive jr-energy AE (the difference between the ff-electronic bond energies), where... 

These equations for odd-electron bonding energies are good for cases where the forms are degenerate or nearly so. In cases where the two structures are not identical in energy, one should use the perturbation theoretic expression (3). 

In this respect it is perspective to experimentally study the electron spectra of different (not only molecular) structures by means of X-ray electron spectroscopy (XES) that allows estimating the electron bond energies in complex systems [2],... 

Internal energy—Refers to all the energies that are present in the system such as kinetic energies of the molecules, ionization energies of the electrons, bond energies, lattice energies, etc. 

The second term in each equation is the energy contribution arising from the interaction of the electron with both of the protons note that this term differs in the two orbitals. We caff this the electronic bonding energy of the electron in each orbital and denote it by jj or . ... 

We calculate the electronic bonding energies for every value of Rar and add to that the nuclear-nuclear repulsion energy to generate the effective potential energy function Veff(l AB) that governs the nuclear motion. 

Molecule Electrons Net bonds Unpaired electrons Bond energy (kj mol" ) Dio- or paramagnetic Bond length (pm)... 

For small S, the three-electron bond energy in He should be not far from (better, a little less than) that of. ... 

The results of our model are seen to agree well with experiment, and were confirmed by ab initio calculations on the same systems (Magnasco, 2008). It was shown there that the single one-electron bond energy parameter (fi-aS) occurring in Equations (25-28) is just the model representation of the one-electron part of the exchange-overlap component of the interaction due to the exchange-overlap densities [a(r)b(r)— Sa2(r)] on A and [b(r)a(r)-Sb2(r)] on B. 

The electronic bond energy Ef for each individual atom i can be defined through the local density of states by... 

The simple VB model makes a very different prediction. By using VB formulas, an overlap-dependent expression is found for the ratio of one-electron to two-electron bonding energies (Table 1 and Eq. [62]) ... 

B. Braida, P. C. Hiberty, and A. Savin,/. Phys. Chem. A, 102, 7872 (1998). A Systematic Failing of Current Density Functionals Overestimation of Two-Center Three-Electron Bonding Energies. 

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