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Administrator<br />

Example 3<br />

In Example 3, however, the hashed bond is<br />

ambiguous because both atoms on the hashed bond<br />

are attached to more than two bonds. In this case<br />

the hashed bond is treated like a solid bond. Wavy<br />

bonds are always treated like solid bonds.<br />

H-Dots and H-Dashes are also used to indicate<br />

stereochemistry. H-Dots become hydrogen atoms<br />

attached to carbon atoms by a wedged bond.<br />

H-Dashes become hydrogen atoms attached by a<br />

wedged hashed bond.<br />

Example 4<br />

H<br />

H<br />

H<br />

H<br />

H<br />

Example 4 shows cis-decalin on the left and<br />

trans-decalin on the right as they would be drawn in<br />

ChemDraw to be read in by Chem3D. Of course,<br />

you can specify a cis fusion with two H-Dots<br />

instead of two H-Dashes.<br />

As a general rule, the more stereo bonds you<br />

include in your model, the greater is the probability<br />

that Chem3D will make correct choices for chirality<br />

and dihedral angles.<br />

When converting two-dimensional structures,<br />

Chem3D uses standard bond lengths and angles as<br />

specified in the current set of parameters. If<br />

Chem3D tries to translate strained ring systems, the<br />

ring closures will not be of the correct length or<br />

angle.<br />

Labels<br />

Chem3D uses the atom labels in a two-dimensional<br />

structure to determine the atom types of the atoms.<br />

Unlabeled atoms are assumed to be carbon. Labels<br />

are converted into atoms and bonds using the same<br />

method as that used to convert the text in a text box<br />

into atoms and bonds. Therefore, labels can contain<br />

several atoms or even substructures.<br />

cis-decalin<br />

trans-decalin<br />

618• 2D to 3D Conversion <strong>CambridgeSoft</strong><br />

Labels

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