How to put a "+" sign onto the canvas:
Select the Reaction tool, then left-click onto the canvas where you would like to place the "+" sign.
It works only if the selection does not contain other "+" signs or a reaction arrow.
How to put an arrow onto the canvas:
Select the Reaction tool, then drag with it on the canvas where you would like to place the arrow. During the dragging a grey feedback shows the future position of the newly forming arrow. Release the button to create the arrow.
If it is necessary the length and the direction of the arrow can be changed afterwards.
Reaction export - Technical details
If the structure on the canvas contains only a single step reaction , then it will be automatically exported as a " reaction file " by Marvin JS *.
(This means that, in the exported file, there will be separate blocks for reactants, products and agents, making it possible to use the exported file in a reaction search.)
In this case, only those file formats are available in the Export dialog which support reactions (MRV, RXN, SMILES, CXSMILES, SMARTS, CXSMARTS, CML, RXN V3000, SDF, CSSDF, CDX, SKC).
When the structure contains more than one reaction or a multistep reaction (or when the reaction converter web service is not available), the structure will not be converted into a reaction file.
In this case, there will not be reactant/product/agent blocks in the exported files, and the "+" signs and arrows of the reaction(s) will be exported as text characters.
The Reaction operators are movable by dragging them on the canvas with active Selection tool.
You can delete reaction operators by clicking on them with active Delete tool, or by selecting them, then pushing the Delete button.
Clicking on the middle of the arrows when the Smart reaction tool is active deletes the arrow.
Merged agents represent a special grouping inside Marvin JS, which gives you the opportunity to handle structures together as one molecule in mrv format. This could be important when you need to visually indicate that separated structures belong together (for example salts) or if you need to use the mrv file in other softwares for example search.
On hover squared brackets appear around the structures, and bonds and atoms in the group are indicated in grey.
Merged group is automatically removed if only one structural part remains in it, or if the group is moved to reactant or product position.
The grouping can be also removed, with Context menu Unmerge Agent(s) option.