Hydrogen orbital diagram

Fig. 1.5. Transversal cross-sectional plots of hydrogen orbitals. Diagrams represent the orbital as a function of the coordinates of a given plane. Elevation correspond to the function value in each point of sectional plane. Reproduced with permission from Fluck E (1989) Allgemeine und anor-ganische Chemie, 6th edn. Quelle and Meyer Verlag, Heidelberg, Wiesbaden...

According to this model, a covalent bond consists of a pair of electrons of opposed spin within an orbital. For example, a hydrogen atom forms a covalent bond by accepting an electron from another atom to complete its Is orbital. Using orbital diagrams, we could write... 

Having seen the development of the molecular orbital diagram for AB2 and AB3 molecules, we will now consider tetrahedral molecules such as CH4, SiH4, or SiF4. In this symmetry, the valence shell s orbital on the central atom transforms as A, whereas the px, py, and pz orbitals transform as T2 (see Table 5.5). For methane, the combination of hydrogen orbitals that transforms as A1 is... 

The hydrogen group orbitals are referred to as symmetry adjusted linear combinations (SALC). Although their development will not be shown here, the molecular orbital diagrams for other tetrahedral molecules are similar. 

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. 

The combination of boron and hydrogen orbitals in the three-center bond can be shown in a molecular orbital diagram as in Figure 13.2. Using this approach to bonding, the structures of some of the... 

Although structures involving methyl groups bonded simultaneously to two carbon atoms by means of an overlap between the hydrogen orbitals and the />-orbitals of the carbon atoms may be readily enough assimilated, the state of structural theory is such that most of the cyclic intermediate or transition state structures are dubbed non-classical. In many cases they are best depicted by molecular orbitals, usually by diagramming the component atomic orbitals in the best position for overlap. Since maximum overlap of the component atomic orbitals imposes certain geometric requirements, pre-... 

Figure 1.6 Molecular orbital diagram for the hydrogen molecule, Ha. Reprinted, by permission, from R. E. Dickerson, H. B. Gray, and G. P. Haight, Jr., Chemical Principles, 3rd ed., p. 446. Copyright 1979 by Pearson Education, Inc.

The energy relationships between unbound atoms and different types of molecular orbitals are summcirized in molecular orbital diagrams, such as the one for hydrogen in Figure 5-8. 

Figure 10.9. Orbitals for a hydrogen atom abstraction reaction. The middle is the orbital diagram for the transition state for H transfer.

Propadiene is represented in Figure 13-4 as if it were two isolated Huckel ring systems. This molecule also may be represented as a stable Mobius system of Att electrons. Draw an orbital diagram of 1,2-propadiene to indicate this relationship. If 1,2-propadiene twisted so that the hydrogens on the ends all were in the same plane, 57, would it be a Huckel or a Mobius polyene, or neither ... 

Orbital diagram of the methyl cation. The methyl cation is similar to BH3. The carbon atom is a bonded to three hydrogen atoms by overlap of its sp2 hybrid orbitals with the s orbitals of hydrogen. A vacant p orbital lies perpendicular to the plane of the three C —H bonds. 

A molecular orbital diagram for a three-center B-H-B bond in diborane. In this diagram, represents an atomic orbital and and represent the bonding and antibonding three-center wave functions, respectively. Note the relative energies of the atomic orbitals on boron and hydrogen atoms (ionization potentials 8.3 eV and 13.6 eV, respectively). 

Hydrogen has one electron, which occupies the Is orbital in its ground state. The configuration for hydrogen is written as Is1, which can be represented by the following orbital diagram ... 

Fig. 19. Molecular orbital diagram showing interaction of two hydrogen Is orbitds with the n levels of O2 in the O2H2 and N2H2 geometries. The angular overlap model is used...

Figure 17. Comparison of the interaction energy curve and orbital diagram of an attractive N- N dimer presenting an A H- -X hydrogen bond ( ), with the curve and diagram for an A-H X interaction found when two C+ cations induce the interaction of two A anions (b). Notice the repulsive character of the A A interaction, and the attractive character of the overall interactions in the C2A2 aggregate.

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