VIBRATIONAL-SPECTRA AND CONFORMATIONS OF 2-METHYLBICYCLO[4.4.0]DECANES AND 3-METHYLBICYCLO[4.4.0]DECANES

The conformations and heats of formation of all trans(T)- and cis(C)-2 - and 3-methyl-substituted T- and Cbicyclo[4.4.0]decanes (BD) were cal culated by the MM2 method of molecular mechanics. It was shown that th e conformationally mobile T-2-Me-CBD and T-3-Me-CBD can exist in norma l conditions as an inseparable mixture of conformers with a different equatorial or axial orientation of the Me groups. The Raman scattering (RS) spectra of 7BD and CBD were investigated. RS bands whose frequen cies were sensitive to the type of ring linkage and orientation (but n ot the position) of the Me substituents were detected in the 700-300 c m-1 region.