Orbital interactions chemical bonds

We have learned the interactions of the same orbitals and chemical bonds between the same atoms. The orbital phase plays a crucial role in the energies and the spacial extensions of the bond orbitals. Here we learn interactions of different orbitals and amplitude of orbitals, using an example of polar bonds between different atoms. 

M. N. Paddon-Row, Some Aspects of Orbital Interactions Through Bonds Physical and Chemical Consequences , Acc Chem. Res. 1982,15,245-251. 

For CO, its HOMO is the lone pair 5 o orbital and its LUMOs are the unoccupied 2 JT orbitals. Elementary chemical bonding theory describes the interaction with a molecule as CO only through chemical bonding contributions through its HOMO and LUMOs. We will see that this is a rather approximate view of the surface chemical bond, because of the important hybridization that occurs in the adsorbing molecule. 

In these cases, interaction between actinides and the ligands were analyzed [74] and confirmed the participation of actinides 5f orbitals for chemical bonding, leading to new modes of actinide-ligand interactions. DFT was also used in order to study the reactivity... 

A is a parameter that can be varied to give the correct amount of ionic character. Another way to view the valence bond picture is that the incorporation of ionic character corrects the overemphasis that the valence bond treatment places on electron correlation. The molecular orbital wavefimction underestimates electron correlation and requires methods such as configuration interaction to correct for it. Although the presence of ionic structures in species such as H2 appears coimterintuitive to many chemists, such species are widely used to explain certain other phenomena such as the ortho/para or meta directing properties of substituted benzene compounds imder electrophilic attack. Moverover, it has been shown that the ionic structures correspond to the deformation of the atomic orbitals when daey are involved in chemical bonds. 

The electron is the lightweight particle that "orbits" outside of the atomic nucleus. Chemical bonding is essentially the interaction of electrons from one atom with the electrons of another atom. The magnitude of the charge on an electron is equal to the charge on a proton. Electrons surround the atom in pathways called orbitals. The inner orbitals surrounding the atom are spherical but the outer orbitals are much more complicated. 

Figure 16-3D shows the simplified representation of the interaction of two helium atoms. This time each helium atom is crosshatched before the two atoms approach. This is to indicate there are already two electrons in the Is orbital. Our rule of orbital occupancy tells us that the Is orbital can contain only two electrons. Consequently, when the second helium atom approaches, its valence orbitals cannot overlap significantly. The helium atom valence electrons fill its valence orbitals, preventing it from approaching a second atom close enough to share electrons. The helium atom forms no chemical bonds. ... 

We have learned about bond orbitals which represent chemical bonds. In this section, we learn how interactions of bonds determine molecular properties. Interactions of bond orbitals give molecular orbitals, which show behaviors of the electrons in molecules. 

Atomic orbitals interact with each other to give bond orbitals (Sect. 1), which mutually interact to give molecular orbitals (Sect. 2). Here we will examine interactions of molecular orbitals, especially those of frontier orbitals important for chemical reactions. 

Gas-surface interactions and reactions on surfaces play a crucial role in many technologically important areas such as corrosion, adhesion, synthesis of new materials, electrochemistry and heterogeneous catalysis. This chapter aims to describe the interaction of gases with metal surfaces in terms of chemical bonding. Molecular orbital and band structure theory are the basic tools for this. We limit ourselves to metals. 

Figure 6.8. Summary of molecular orbital theory for homonuclear molecules. Note how the stability of a chemical bond depends both on the interaction strength and the filling of the orbitals.

In the case of covalent compounds, crystal-field theory is a poor model for estimating electric field gradients because of the extensive participation of ligand atomic orbitals in the chemical bonds. MO calculations are a much better choice, since the corresponding interactions are considered, and realistic (noninteger) population numbers are obtained for the central metal as well as the ligand atomic orbitals. 

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