electronegativity brackets with chemfig (?)

Question

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.

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.

Output

Code

\documentclass[margin=10pt]{standalone}
\usepackage{chemfig}

\begin{document}

\chemfig{H-[@{a1}:45]O-[@{a2}:-45]H}\pgfresetboundingbox

    \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);}

\end{document}