Molecular-Orbital Energies in

The most stable orbital in benzene is (iri ). The energy of this MO is calculated below  

There are a total of thirty valence electrons in benzene. Twenty-four are used in r bonding (six C—C, six C—H bonds), leaving six for the TT-molecular-orbital levels shown in Fig. 8-18. This gives the ground state (xi ) (ir2 ) (7r3 ) j and a total of three tt bonds. Each carbon-carbon bond consists of one full r bond and half a tr bond. The O C bond length in C Hs, 1.397 A, lies between the C—C and 0=C bond lengths. 

8-17 RESONANCE ENERGY IN CeHg Benzene is actually more stable than might be expected for a system of six C—C single bonds and three C—C ir bonds. This added stability is due to the fact that the electrons in the three ir bonds are delocalit(ed over all six carbons. This is evident both from the molec- 

In the MO view, the total gain in QHe stability due to bonding is calculated in units of /Sco as follows  

If we did not allow the delocalization of electrons in CeHc, we would have a system of three isolated double bonds (only one of the Kekul structures shown in Fig. 8-19). Let us calculate the t bonding stability of three isolated double bonds. 

---

Figure 1.7 Schematic representation of molecular orbital energies in organic molecules...

Fig. 20. 2pir molecular orbital energies in the Huckel approximation for simple radicals (a) and olefins (b). 

Debnath, A.K., Hansch, C. (1992) Structure-activity relationship of genotoxic polycyclic aromatic nitro compounds. Further evidence for the importance of hydrophobicity and molecular orbital energies in genetic toxicity. Environ. Mol. Mutagen. 20, 140-144. 

Fig. 3. The relative position of molecular orbital energies in regular octahedral MX, and tetrahedral MX, complexes. The arrangement is known from the M.O. interpretation of electron transfer spectra. The relative distances to the two highest empty sets of orbitals is underestimated, it may be much larger.

Table 5.3. Comparison of experimental quartz and olivine relative molecular-orbital energies (in eV) with MS-SCF-Za results for silicon-oxygen bond lengths. /J(Si-O) = 1.609 and 1.634 A...

Figure 7.3 Molecular orbital energies in benzene approaches simplify considerably owing to the orthogonality of the MOs, and thereby ...

Huang, Q.G., Kong, L. and Wang, L. (1996). Applications of Frontier Molecular Orbital Energies in QSAR Studies. Bull.Environ.Contam. Toxicol., 56, 758-765. 

Partial representation of the molecular orbital energies In (a) diamond and (b) a typical metal. 

The molecular orbital energies in this two orbital case, e, (/ = 1,2). are obtained by solving the secular determinant (equation 1.30) shown in equation 2.5 for this particular example... 

Fig. 1.10. Molecular orbital energies in atomic units for methane.

It is convenient to show the relative molecular-orbital energies in a diagram. Such a diagram for H2+ is shown in Fig. 2-8. The valence orbitals of the combining atoms are represented in the outside columns and are ordered in terms of their coulomb energy. The most stable valence orbitals are placed lowest in the diagram. Since Ira and Ir have the same coulomb energy, these levels are placed directly opposite one another. 

Huang, Q.-G., L. Kong, and L.S. Wang. 1996. Application of frontier molecular orbital energies in QSAR studies. Bull. Environ. Contam. Toxicol. 56(5) 758-765. 

Figure 1.10. A schematic representation of a few of the molecular orbital energies in hydrogen fluoride (HF). The sigma (o) and pi (ti) bonding relative positions are shown, but only the sigma (o ) antibonding orbital position is provided.

---