VB mixing diagram

Scheme 19. A VB Mixing Diagram Showing the Splitting of the Kekule Structures into the Twin States, , and P a...

Scheme 36. (a) Kekule Structures for Naphthalene, (b) A VB Mixing Diagram Which Shows the Twin States Generated from the Ag and B2u Combinations of the Kekule Structures... 

FIGURE 2.1 A VB mixing diagram showing the formation of the states of the H—H bond from the covalent and ionic structures. 

FIGURE 5.2 A VB mixing diagram for the formation of the symmetry-adapted states of 02 from the biradical (1, 1 ) and perfectly paired (2, 2 ) structures. 

Benzene is another molecule where molecular symmetry can be useful for construction of the ground and covalent excited states (5,6,16,17,24). The molecule possesses five covalent VB Rumer structures, two are the Kekule structures, and the three Dewar types, shown in Fig. 7.4a. It is seen that the Kekule structures are mutually transformable by the D6h point group operations i, C2, and av. Consequently, we can make two linear combinations the positive one is the totally symmetric Aig state, which gives rise to the ground state, while the negative one is the B2U state, which corresponds to the excited state. This is shown in the VB mixing diagram in Fig. 7.4b. 

FIGURE 7.6 (a) Kekule structures of naphthalene, (b) The corresponding VB mixing diagram, (c) The b2u mode that interchanges Ki and K, in the VBSCD. 

FIGURE 7.9 (a) Covalent resonance structures for butadiene and their overlap integral, (b) A VB mixing diagram of the resonance structures yielding the covalent ground and excited states, (c) The major 1,4-biradical character of the 2 Ag state. 

The Rc structure transforms as Bi (in C v), while Rr and / are mutually transformable via the crv and C2 symmetry elements, and therefore their linear combinations transform as Bi and A2. Part (b) shows the VB mixing diagram... 

Figure 6.8 shows a VB mixing diagram that describes the bonding in Li2- It is seen that suffers from PauH repulsion relative to the two separate Li atoms, indicated in Figure 6.8 as At the same time, the fundamental structure mixes with the excited structures and is stabilized by a mixing energy, which is a... 

Figure 6.8 A VB-mixing diagram that describes the bonding in Lij as a result of mixing of the excited VB structures into the fundamental structure, is the Pauli repulsion energy of relative to 2Li at...

Figure 1 describes the Pauling-Lewis perspective of electron-pair bonding in terms of VB mixing diagrams [9]. Three stmctures, one covalent, d>cov(A—x)> and two ionic (Mies, < a+x and d>A-x+ are required to describe an electron pair bond A-X, which may either be homo- or heteronuclear. 

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