2EFlow arrows should not start on a radical electron

I'm not saying that the following image is a correct representation of what actually goes on when Al reacts with N to form aluminum nitride, but under no circumstances should a 2-electron flow arrow start on a single (radical) electron. Nor should 1-electron flow arrows start on a lone pair, though topic that is debatable for higher-level students.

For the same problem, when I try to use 3 1-electron flow arrows, 2 of those arrows are superimposed so that the end-result looks like there are only 2 1-electron flow arrows. I know I can grab and drag one of those arrows with some tinkering and rearrange it so it shows up differently, but I'm sure my students will be quite confused between these two scenarios.

 

It also looks (but I'm not sure) that charges and atom mapping labels have moved even further away from their atom labels than was previously the case. In 5.2 it was annoying, but with the floating lone pairs and radical electrons in 5.4 it's become a major headache for my student to know what belongs together.

A way to untangle this or to use custom settings would be highly appreciated.

Thanks.

 

MSketch 5.4.1.1 / Java SE 6 (build 1.6.0_26-b03) / Win XP SP3 / either FF3.6 or IE 8.0.6

Hi,

In this case You have drawn two electron flow arrow has the same starting point, and lone pairs are visible, so Marvin  calculates a valid starting point for electron flows and starts the two arrows from that same graphical point. We have some discussion on the forum and in mails about electron flows, and those were about one electron flow arrow from one point, and moving more electrons in more than one steps. I will talk about handling these cases with the Marvin project manager.

The problem about one arrow covering another is the same. We draw the arrow in a constant angle before the user drags it, and after drawing one arrow to the right and one to the left, the third arrow will cover one of them.

The charges and atom mappings can be close or far from the atom symbol. These two distance values are the same as far as I know, but that is true that for example the charge is far from the atom symbol more often than the previous cases. This is because I had to rewrite this code and the first goal was to remove all exceptions, and bugs from eflows, and remove most of the crossings, and it resulted in moving the charge further more times, but we already working on some tasks to improve the drawing. (In case of bonds it's a little further, but the arrow ends were crossing double and triple bonds in the previous release.)

That's right that a 2 electron flow should not start form a radical, it is only because of the bug of the same starting point.

After all requests we use these specification for electron flow display:

http://www.chemaxon.com/marvin/help/sketch/gui/electronflow.html

so in one special case a one electron flow can start from a lone pair.

Best Regards,

Peter