Abstract: Monodeprotonation of Fp2 ($, q2-1, 7-octadiene)(BF4),[4, Fp= C, H, Fe (CO),] at 0 “C with n-Bu3N leads to the formation of the trans-1, 2-disubstituted cyclopentane complex 6- t as the major product. Evidence is provided that this is the kinetic product. The structure of 6- t is established by degradation to trans-1-methyl-2-vinylcyclopentane and by comparison of this with synthetic material. By contrast, the homologous 1, 8-nonadiene complex 11 is ...