The following are all MM2 energies with MMFF94 in parentheses).
Chair: 6.55 kcal, twist-boat 11.919. No pure boat form is normally locatable (13.03) although many a text book on organic chemistry implies that it is a true minimum, albeit somewhat higher in energy than the twist-boat. As noted in the references, it is of course a racemisation transition state connecting the two enantiomeric twist-boat forms. See the relevant section of the lecture course on conformational analysis.
RS/SR = 6.96 (all trans conformation), 7.909 (syn conformation); RR/SS = 6.744 (halogens anti, methyl syn), 7.118 (halogens syn, methyl anti). The MOPAC RM1 values (which take into account stereoelectronic factors) are RR/SS = -29.02 (halogens anti, methyl syn), -28.87 (halogens syn, methyl anti)
1.2 Benzene, -0.574, Naphthalene, -4.430, phenanthrene, -3.552 (planar), benzophenanthrene, 7.760 (non planar), Pentahelicene 14.31 (very non planar), hexahelicene, 19.056 (note the problem building this molecule). Note that these increments behave in an interesting fashion, perhaps because at some stage Van der Waals (dispersion) interactions between the newly overlapping layers start to make an effect!
2.8 Ketone: Isomer 1, 208.5. angles Angle to Hb 88.1, angle to Ha 49.5. Ketone Isomer 2, 196.4. Angle to Hb, 21.2, Angle to Ha 16.9 (these two ketone isomers are almost certainly an artefact of the Tripos force field. An MO calculation (B3LYP/6-31G(d) ) gives only one isomer, with angle to Hb 57.3, angle to Ha, 17.3. This is an ideal candidate for following up with a more accurate calculation according to the instructions given at the end of this course). Enol from Hb: 369.2, Enol from Ha: 491.0.
