Pentadienyl radical, resonance forms

Draw three resonance forms for the pentadienyl radical. A radical is a substance that contains a single, unpaired electron in one of its orbitals, denoted by a dot ( )-... 

Thus, the three resonance forms for the pentadienyl radical are ... 

Resolution (enantiomers), 307-309 Resonance, 43-47 acetate ion and, 43 acetone anion and. 45 acyl cations and, 558 allylic carbocations and, 488-489 allylic radical and, 341 arylamines and, 924 benzene and, 44. 521 benzylic carbocation and, 377 benzylic radical and, 578 carbonate ion and. 47 carboxylate ions and, 756-757 enolate ions and, 850 naphthalene and, 532 pentadienyl radical and. 48 phenoxide ions and, 605-606 Resonance effect, 562 Resonance forms, 43... 

A common biologically active radical is the pentadienyl radical, RCHCHCHCHCHR, where the carbons form a long chain, with R and R, which can be a number of different organic groups, at each end. Draw three resonance structures for this compound that maintain carbon s valence of four. 

Sketch the molecular orbitals for the pentadienyl system in order of ascending energy (see Figures 14-2 and 14-7). Indicate how many electrons are present, and in which orbitals, for (a) the radical (b) the cation (c) the anion (see Figures 14-3 and 14-7). Draw all reasonable resonance forms for any one of these three species. 

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