Phenylsodium Compounds with η 3 ‐Allyl or η 6 ‐Phenyl Coordination

In spite of the identical negative charge available , phenyl‐substituted allyl anions can be coordinated differently by counter ions. Thus the Na(pmdta) ⊕ (pmdta = pentamethyldiethylenetriamine) ion coordinates in a η 3 manner to the allyl system in 1 , but in a η 6 manner to the phenyl ring in 2 . Apparently the energy surface for the migration of the cation over the planar carbanion in 2 contains no large energy barriers and for steric reasons the Na(pmta) ⊕ ion avoids coordinating with the allyl system of the cyclohexenyl unit.