Orbit diagram construction

Selected structural data for /i-peroxo cobalt(III) complexes are included in Table 57. Orbital diagrams constructed for Co—O—O bonds in N4Co(02)CoN4 species show that irons bent bonds are the most stable and this is what is observed for the monobridged complexes. Dibridging forces the /i-peroxo group to adopt a skewed cis geometry except in cases (e.g. [(tren)Co(/i-tren,02)Co-... 

Construct orbital diagrams for atoms of sulfur and iron. 

Reality Check To construct an orbital diagram, start with the electron configuration and apply Hund s rule. 

Strategy First, find the number of valence electrons. Then construct an orbital diagram, filling the available molecular orbitals (Figure 3) in order of increasing energy. 

The data show that bond energies for these three diatomic molecules increase moving across the second row of the periodic table. We must construct molecular orbital diagrams for the three molecules and use the results to interpret the trend. 

It will be helpful to construct a state diagram from the orbital diagram. 

In this chapter, the descriptions of molecular structure will be primarily in terms of a valence bond approach, but the molecular orbital method will be discussed in Chapter 5. As we shall see, construction of molecular orbital diagrams for polyatomic species is simplified by making use of symmetry, which will also be discussed in Chapter 5. 

Having considered the case of the H20 molecule, we would like to be able to use the same procedures to construct the qualitative molecular orbital diagrams for molecules having other structures. To do this requires that we know how the orbitals of the central atom transform when the symmetry is different. Table 5.5 shows how the s and p orbitals are transformed, and more extensive tables can be found in the comprehensive books listed at the end of this chapter. 

If we now consider a planar molecule like BF3 (D3f, symmetry), the z-axis is defined as the C3 axis. One of the B-F bonds lies along the x-axis as shown in Figure 5.9. The symmetry elements present for this molecule include the C3 axis, three C2 axes (coincident with the B-F bonds and perpendicular to the C3 axis), three mirror planes each containing a C2 axis and the C3 axis, and the identity. Thus, there are 12 symmetry operations that can be performed with this molecule. It can be shown that the px and py orbitals both transform as E and the pz orbital transforms as A, ". The s orbital is A/ (the prime indicating symmetry with respect to ah). Similarly, we could find that the fluorine pz orbitals are Av Ev and E1. The qualitative molecular orbital diagram can then be constructed as shown in Figure 5.10. 

Use the symmetry of the atomic orbitals of the central atom to construct (using appropriate hydrogen group orbitals) the molecular orbital diagrams for the following. 

Under certain conditions (such as in interstellar space), the OH radical has been observed. Construct the molecular orbital diagram for this species. Determine the bond order and determine what type of orbital contains the unpaired electron. 

Figure A.15 Energy diagram for the adsorption of a simple diatomic molecule on a d-metal. Chemisorption orbitals are constructed from both the bonding and the antibonding levels of the molecule. As the latter becomes partially occupied, the intramolecular bond of the adsorbate has been activated.

FIGURE 3.4 Molecular level alignment diagrams constructed using the HOMO and vacuum levels measured using UPS. The lowest unoccupied molecular orbital LUMO positions are inferred assuming a HOMO/LUMO gap equal to the onset of optical absorption. The chemical structure of CuPc is shown. (From Hill, I.G. and Kahn, A., J. Appl. Phys., 86, 2116, 1991. With permission.)... 

Construct the molecular orbital diagram for diatomic nitrogen, N2. Is this molecule paramagnetic or diamagnetic ... 

Construct a qualitative molecular orbital diagram lor CIO and compare it to the one (resented in Figure 531 for NOT. 

What is interesting is diat this overlap model allows the orbital diagram to be constructed widiout concerning itself widi electrons. The MOs produced by die... 

FIGURE 27. General molecular orbital diagrams showing the construction of the orbitals of 14 electron Cp2M metallocenes, in parallel (D d) and bent (C2V) conformations, from the orbitals of the Cp2 and M fragments (only the occupied orbitals are shown). Adapted from Reference 389... 

The spin-free Gel fand states span the several irreducible representation spaces. They are uniquely labeled by Gel fand diagrams constructed by adding spin-free orbitals in nondescending order along rows and ascending order down... 

Construct the molecular orbital diagram for LiH and discuss its major differences from those of Li2 and H2. 

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