METAL-ALKYL AND METAL-ARYL COMPOUNDS .46. PHENYLSODIUM COMPOUNDS WITH ETA-3-ALLYL OR ETA-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 eta-3 manner to the allyl system in 1, but in a eta-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.