Cyclopentadienyl radical, molecular orbitals

N t/ l Five cyclopentadienyl molecular orbitals 4f Cyclopentadienyl cation (four 77 electrons) 4f Cyclopentadienyl radical (five 77 electrons) -H- Cyclopentadienyl anion (six 7r electrons)... 

Five (yclopcntadienyl molecular orbitals Cyciopentadienyi cation (four 7T electrons) Cydopeufadienyi radical (five electrons) Cyclopentadienyl anion (six 71 electrons)... 

Five Q clopcDtadienyl molecular orbitals (tyi opentadienyi cation (four fT electrons) CVcIopenfadionyl radical five fx electrons) Cyclopentadienyl anion (.[Pg.596]

The degeneracy of the /a and is molecular orbitals in the cyclopentadienyl radical can be broken by the electronic effect of the substituent. The /A orbital has a node at Cl, and is unaffected, but the i /s orbital, with a high coefficient at Cl, has its energy raised by an electon-releasing substituent, and lowered by an electron-attracting substituent, placing the unpaired electron preferentially in the i /s or /a orbital, respectively, as shown in Figure 20-1. 

The state of the cyclopentadienyl radical may be described in terms of five molecular orbitals, which are formed from the jr-type orbitals of the five carbon atoms. These molecular orbitals, which are shown in Fig. 2, are one of iT-type (a), containing two electrons two of ZT-type c), containing one and two electrons,... 

Using the internet, find a Huckei determinant soiver and determine the reiative energies of the tt molecular orbitals for (a) the allyl radical, which has three tt electrons, and (b) the cyclopentadienyl anion, which has six tt electrons. 

The relative energy levels of the five tt molecular orbitals of the cyclopentadienyl system are similar to those in benzene. That is, there is a single lowest-energy MO, above which the orbitals come in degenerate pairs. Draw a diagram like that in Figure 15.5, and tell which of the five orbitals are occupied in the cation, radical, and anion. 

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