The capture of sym-[8]annuldiyne: the cyclooctadienyne-eta2-ynyl potassium zwitterionic radical.
[reaction: see text] Reaction of 1,4-dibromo-[8]annulene (C(8)H(6)Br(2)) with potassium tert-butoxide in THF followed by exposure to potassium metal leads to the formation of the anion radical of sym-[8]annuldiyne. The rapid interchange of Jahn-Teller-induced alternating bond angle conformers of sym-[8]annuldiyne is halted by ion association with a metal-crown ether complex forming the cyclooctadienyne-eta(2)-ynyl potassium zwitterionic radical, rendering all four protons nonequivalent. Neutral sym-[8]annuldiyne can form the [2 + 2] polymer, which is not soluble in the THF solution.
Kiesewetter
Matthew K
MK
Department of Chemistry, Illinois State University, Normal, Illinois 61790-4160, USA.
Reiter
Richard C
RC
Stevenson
Cheryl D
CD