More Examples that Show How Delocalized Electrons Increase Stability

Notice that the number of rr molecular orbitals is the same as the number of atoms in the ring because each ring atom contributes a p orbital. (Recall that orbitals are conserved see Section 1.6.) [Pg.351]

Molecular orbitals below the midpoint of the cyclic structure are bonding molecular orbitals, those above the midpoint are antibonding molecular orbitals, and any at the midpoint are nonbonding molecular orbitals. This simple scheme is sometimes called a Frost device (or a Frost circle) in honor of Arthur A. Frost, the scientist who devised it. [Pg.351]

Antiaromatic compounds have an even number of pairs of rr electrons. Therefore, either they are unable to fill their bonding orbitals (cylopentadienyl cation) or they have a pair of TT electrons left over after the bonding orbitals are filled (cyclobutadiene). Hund s rule requires that these two electrons go into two different degenerate orbitals (Section 1.2). [Pg.351]

How many bonding, nonbonding, and antibonding tt molecular orbitals does cyclobutadiene have In which molecular orbitals are the tt electrons [Pg.351]

13 MORE EXAMPLES THAT SHOW HOW DELOCALIZED ELECTRONS INCREASE STABILITY [Pg.351]

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