User f93a4318a2
11-04-2011 14:32:57
In Chemdraw there is a plain dashed bond type which is in addition to the wedged dashed bond types. It would be very useful if Mavin Sketch supported this bond type. This has support in the literature (Enantiomer Vol 2 pp473 and Enantiomer Vol 4 pp483) as a way of getting past the problem of which atom the narrow end of the wedge should be on. Marvin already supports the bold single bond. See the attached image showing the usage.
Rich
ChemAxon 990acf0dec
13-04-2011 05:33:20
Hi Rich,
What is the problem with using the Down Wedge bond in this case?
Anyway, we register this new bond type as a feature request.
Best regards,
Akos
User f93a4318a2
13-04-2011 13:11:23
Hi Arkos,
Thanks for adding in the request. Some people get confused by the different orientations of the direction of the wedge and whether that means a change in stereochemistry. As mentioned in the quoted papers one way to get around this is to use the plain dashed bond (same as the wedge without the wedginess) which is understood as a "going away bond". This makes for an unambiguous understanding of stereochemistry.
Rich
ChemAxon 990acf0dec
14-04-2011 09:54:58
Hi Rich,
We have an issue here: currently a coordinate bond connected to a multicenter atom is displayed on the same way as the unwedged hashed bond. This complicates the implementation of this feature...
We will discuss internally how to solve this, and will inform you in this topic.
Best regards,
Akos
User 870ab5b546
21-04-2011 16:58:41
Rich, correct me if I'm wrong, but you are asking not for a dashed bond, but for a hashed bond that is not wedge-shaped, i.e. does not connote direction.
See the attached picture (which I had to draw in ChemDraw). Hashed and bold bonds can be directional or nondirectional. For compounds with multiple stereocenters, the convention is to use the directional hashed and bold bonds when a compound is diastereopure and enantioenriched, and to use the nondirectional hashed and bold bonds when a compound is diastereopure and racemic. There is no directional version of a wavy bond.
The dashed bond is used for several other purposes, usually to indicate a partial bond.
It would be useful to have a flag that allows the user to convert all directional bonds to nondirectional ones for display purposes only. The MRV representations would not change.
User f93a4318a2
21-04-2011 17:12:01
You are correct, the non-directional hashed bond is what I was referring to and tried to illustrate in the chemdraw image I posted. The boldness and hashness still indicate above and below the plane respectively.
Rich
ChemAxon 990acf0dec
26-04-2011 09:16:38
Hi,
Yes, I understood, but as I said, it is currently used for the display of coordinate bonds when the bond is connected to a multicenter atom (see the attached structure). We will discuss it internally, how to solve this issue.
Best regards,
Akos
User 870ab5b546
26-04-2011 12:49:50
I recommend that you use a regular straight bond for the multicenter bonds, as is conventional. The context will make it obvious that it is a multicenter bond.
ChemAxon 990acf0dec
03-05-2011 19:43:07
Hi Bob,
Is it really "conventional" to draw the coordinate bonds to multicenter atoms with a solid bond? I know that e.g. in case of ferrocenes it is used many times, but isn't it the case just because there was no any alternative in other chemical sketchers programs?
Anyway, I think the best solution is to have an option in the preferences to dispplay the coordinate bond as a single bond, both in case of multicenter and in case of single atoms. We still have to decide what should be the default though. Which one do you vite for?
Thanks for sharing your opinion with us.
Best regards,
Akos
User 870ab5b546
03-05-2011 20:42:13
Yes, I believe it is conventional to draw the coordinate bonds to multicenter atoms with a solid bond. I think the default should be the solid bond.