Bent orbital energies

Figure 9.4. Walsh diagram showing correlation of orhitals between bent and hnear triatomic molecules, and suggesting variation in orbital energy with bond angle.

Fig. 6.16 Molecular Orbital pictures and qnalilalive energies of linear and bent AB molecules. Open and shaded areas represent differences in sign (+ or ) of the wave functions. Changes in shape which increase in-phase overlap lower the molecular orbital energy- From Gimarc.

Figure 9 Variation of orbital energies in HAH molecule on going from 90° bent molecule to linear molecule. The classification of states, built from s and p atomic orbitals, is discussed in the main text. The steep rise in the curve joining ai and favours the bent molecular form for H2O, whereas with four valence electrons, as in BeH2 or HgH2, the linear configuration is favoured. This argument is based on an intimate relation, which Walsh assumed, between the sum of orbital energies and total energy. Density theory in its simplest form supplies such a relation, namely equation (84). The figure is a schematic version of that of Walsh,46 who noted that the line 180° must be either a maximum or a minimum...

Figure 20 Molecular orbital energy level diagram of bent H2O...

Figure 2.7 Diagram of the MO orbital energies (S — 0) for the carbon-carbon interaction in the cPn2 description of the double bond (left) and in the equivalent B12B22 bent bond description (right)...

Figure 2. The change in bonding characteristics and orbital energies in linear and bent transition metal dioxo species...

Problem 14.7 Suggest a molecular orbital description of the frans-bent, high-energy structure of Si2H2. 

Angle strain exists in a cyclopropane ring because the orbitals comprising the carbon-carbon cr bonds cannot overlap as effectively (Fig. 4.9a) as they do in alkanes (where perfect end-on overlap is possible). The carbon—carbon bonds of cyclopropane are often described as being bent. Orbital overlap is less effective. (The orbitals used for these bonds are not purely sp they contain more p character.) The carbon-carbon bonds of cyclopropane are weaker, and as a result the molecule has greater potential energy. 

Since the majority of the occupied orbital energies are minimized at = 180", CO2 has linear geometry. In NO2, which has 17 valence electrons, the bent geometry becomes favored because the extra electron goes into the ba orbital whose energy drops sharply when the bond angle is decreased. The electron configuration of NO 2 then becomes... 

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