Dipole Moments, Configuration, and Conformation of Tricyclo[5.1.0.03,5]octane Derivatives and Related Compounds

Tricyclo[5.1.0.0^3-5]octane (VI), 4,4-dibromotricyclo[5.1.0.0^3-5]octane (Y), and 4,4,8,8-tetrabromotricyclo-[5.1.0.0^3-5]octane (III) have been prepared. The dipole moments of these compounds as well as those of norcarane (VIII), Δ³-norcarene (IV), 7,7-dibromobicyclo[4.1.0]heptane (VII), Δ³-7,7-dibromobicyclo [4.1.0] heptene (II), 1,4-eyclohexadiene (I), cyclohexene, and cyclopentene have been measured. Zero dipole moment for III proves its configuration is trans and the six-membered ring has a relatively flat conformation. The methods of preparation indicate a trans configuration for VI and Y and the dipole moment values favor nearly flat conformations for the six-membered rings in these compounds. Cyclohexene and cyclopentene were found to have dipole moments of 0.21 D. which are considerably smaller than most values in the literature. Norcarane has a moment of 0,44 D. The evidence indicates the central ring is relatively flat when either cyclopropane or olefinic groups are on opposite sides of a six-membered ring.