I've been trying to draw something like this with chemfig:


Specifically I'm trying to create those red brackets around the bonds indicating that due the Oxygen's higher electronegativity, it has a greater pull on the electrons than Hydrogen.

Since I never learned chemistry in English, I have no idea how these things are called (or even if they are used in actual chemistry?), that's why I apologize having to ask this question.

1 Answer 1


Here it is. chemfig basically works like Tikz. You can set nodes and use those nodes to draw arrows, etc.

I did the brackets by drawing arcs, and setting nodes on the lines. It would have been easier if each "atom" was a node, but I haven't found anything in the documentation. In any case, if you discover something like that, you can remove the extra nodes and use the atoms themselves as a base for other graphics.

I also added \pgfresetboundingbox to remove some extra white space that was appearing on the right. Not much, but it was noticeable enough.


figure 1





    \chemmove{\draw[red,thick] (a1)+(-8.3pt,-2.8pt) arc (-180:-90:5pt);}\pgfresetboundingbox
    \chemmove{\draw[red,thick] (a2)+(3pt,-7.8pt) arc (-90:0:5pt);}

  • Works great, thanks. As I'm not that experienced with TeX, I'd like to ask if there would be a theoretical way to directly implement this via a macro (?) to simplify it? Something like C((-[:0]O) to draw it into the bond (probably not). Any generalization would be nice.
    – Philip K.
    May 8, 2015 at 20:43
  • @user3107501 You're welcome! :)
    – Alenanno
    May 8, 2015 at 20:45
  • @user3107501 I didn't get notified of your comment edit. Anyway, if you mean remove those commands and place them in the preamble, you can issue a \newcommand. I think it would work. But I never worked with chemfig so I don't know off the top of my head. :D
    – Alenanno
    May 9, 2015 at 13:16

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