An R-group can describe a set of derivatives in one single structure (substitution variation).
To create an R-group, follow the steps below.
To add attachment points for the R-definitions, use Atom > R-group Attachment or R-group Attachment from the context menu. Alternatively, when you draw the R-definitions and the mouse cursor still shows R1, clicking on an atom of the definition will toggle the attachment point on that atom. Divalent R-groups must have two attachment points defined.
To change the order of the attachment points, select an attachment point, and set the new number by using the R-group Attachment Order option from the context menu or the Atom > R-group Attachment Order menu item.
You can define additional conditions, for example, occurrence, rest H, and if-then expressions to R-groups in the R-logic dialog window.
To do this, follow the steps below.
R-logic can be visualized by switching on the View > Advanced > R-logic menu option. R-groups can be formatted as other atom labels. For more information, see Atom Label Editor. R-logic does not apply to R0.
In the case of one attachment point, the connections are not numbered, only marked by a wavy line on the substituent side. In the case of more than one attachment point, the connections are marked by numbers (ligand order) on the root structure. Connection points on the substituents are marked with a wavy line, and the order is indicated by numbers (except for the first one).
The ligand order on a bond can be changed using Bond > Ligand order.