, while sp2 angles are most stable at 120. To avoid the strain, the molecule assumes a nonplanar shape, in which orbital overlap is greatly diminished.241 Single- and double-bond distances in 78 are, respectively, 1.46 and 1.33 A ˚ , which is expected for a compound made up of four individual double bonds.240 The reactivity is also what would be expected for a linear polyene. Reactive intermediates can be formed in solution. Dehydroha- logenation of bromocyclooctatetraene at 100C has been reported, for example, and trapping by immediate electron transfer gave a stable solution of the [8]annu- lyne anion radical.242 The cyclooctadiendiynes 93 and 94 are planar conjugated eight-electron systems (the four extra triple-bond electrons do not participate), which nmr evidence show to be antiaromatic.243 There is evidence that part of the reason for the lack of planarity in 78 itself is that a planar molecular would have to be antiaromatic.244 The cycloheptatrienyl anion (61) also has eight electrons, but does not behave like an aromatic system.151 The bond lengths for a series of molecules containing the cycloheptatrienide anion have recently been published.245 The NMR spectrum