Kinetics of bond shift and charge transfer in dialkynylphenylene-bridged dicyclooctatetraenes and their dianions

1,4-Dicyclooctatetraenyl-1,3-butadiyne and p-, m-, and o-di(cyclooctatetraenylethynyl)benzene (1-4, respectively) and their dipotassium sales (1(2-)-4(2-)) in TNP-d(8) have been synthesized and studied by dynamic NMR spectroscopy, Rate constants for bond shift (k(BS)) in the neutral cyclooctatetraene (COT) rings of 1-4 and 1(2-)-4(2-) and for intramolecular charge (electron and cation) transfer (k(CT)) between the dianion and the neutral COT rings in 1(2-)-4(2-) have been determined. C-13 NMR chemical shifts and AML pi-charges as well as the values of k(CT) are interpreted on the basis of a stronger through-bond interaction between the COT rings in the order 1(2-) much greater than 2(2-) greater than or equal to 4(2-) > 3(2-). Similarly, k(BS) decreases in the order 1(2-) much greater than 4(2-) > 2(2-) > 3(2-) on going from 1-4 to the corresponding dianions, Analysis of the AM I pi-charge densities suggests that these differences are primarily due to a through-bond effect with an additional through-space contribution from the electric field of the dianion ring For bond shift in 4(2-).