THE RADICAL-ANION OF TETRAPHENYLENE REVISITED

The tetraphenylene radical anion (2(.-)) generated by Na, K and Cs red uction in tetrahydrofuran and 2-methyltetrahydrofuran has been investi gated by EPR/ENDOR spectroscopy. The results clearly establish that th e decrease of the molecular symmetry of 2(.-) from D-2d to C-2v detect ed upon exhaustive reduction arises from ion-pair formation. This find ing unequivocally rules out the assumption stated in previous papers t hat the EPR spectra mirroring the lower symmetry originate in a bis(bi phenylene)-like geometry of 2(.-).