Constructing and Optimizing a Set of Isomers Automatically

Once the corrected strain energy differences have been calculated, they can be used to determine the isomer proportions using Eq. (17.11). For example, the difference between the statistically corrected energies of the lel3 and lel2ob con-formers is — 1.65 kj mol . Thus, Eq. (17.11) becomes 

the ratio oflel2ob to leh is 1.95 (with the former dominating because it has a lower energy). You should now calculate the ratios for the other conformers and use these to determine the proportions of each conformer. Check your results against those given in Table 17.1. 

Compare the strain energies of the two conformational isomers and calculate the proportion of each expected in solution at room temperature. Measure the contacts between the methyl group and the remainder of the complex. Consider how this contributes to the difference in strain energies. 

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